Guidance on Rules for small supplies

The Rules define networked supplies as:

Drinking water supplies that provide drinking water via a distribution system at a pressure and volume to meet consumer demand, or at a restricted flow and volume.

These supplies may include storage facilities within the network to manage demand.

Below are some examples of networked small drinking water supplies.  

• A water supply for a settlement of 40 houses is delivered through a network of pipes. The majority of these houses are holiday homes and unoccupied outside of the school holidays. While the holiday population sometimes increases to 120 people, the base population for most of the year is 35 people.  

• A town centre has its own water supply piped to some shops, a council office and some council flats. The population of staff, residents and regular visitors who use the water at the buildings totals 85 people. 

The Rules define self-supplied building supplies as:

Water supplies (excluding domestic self-supplies) which provide drinking water to up to 10 buildings on one site (within the boundaries of one property, or within the boundaries of two or more properties with common ownership arrangements) and provide water to more than 25 people.

Below are some examples of self-supplied small drinking water supplies.  

• A rural school has 55 students and staff and its own water supply from a bore. The supply is connected to three separate classroom buildings, a maintenance shed and administration building, which are all located on the same property. 

• A marae consists of a wharenui (meeting house), wharekai (dining hall), ablutions block, and a kitchen, as well as a kōhanga reo and whare kaumātua (kaumātua flats), totalling eight buildings. The marae water supply is a roof supply that is distributed to these buildings which are located on three neighbouring properties that are all owned by the same entity. The marae population on a regular day, including whare kaumātua residents and regular kōhanga reo students, is 45 people. 

As a water supplier, you need to monitor the number of people the water supply is servicing, because the more people drinking the water, the more people that could become sick if something goes wrong. If the population exceeds 100 people, you must do additional monitoring until the population returns to below 100 people.

If the population exceeds 100 people, you must do additional monitoring until the population returns to below 100 people. In this case, see the Varying Population module in the Rules, and the Varying Population rules section of this guidance.

Rule G1 requires reporting of compliance with level 1 monitoring rules annually. This includes reporting whether you complied with six rules: S1.1, S1.2, S1.3, T1.1, T1.2 and D1.1.

Your compliance report must contain details of samples taken to meet these rules. Sample details should contain the following information.

• Supply component ID – The identifier that is allocated to the particular component of the supply the sample is from, either the source abstraction point, treatment plant or distribution zone. The supply component ID can be found in your supply information dashboard after logging into the Authority’s self-service online portal, Hinekōrako.
• Sample ID and sample date – Information needed for traceability purposes of each sample. The sample ID (which is up to the supplier to decide) and sample date should be written on the sample bottle when the sample is collected. It should then be included on the sample result form that is provided by the laboratory that does the analysis. This information identifies for the Authority that the sample is legitimate, and links to when and where it was collected as well as the test results from the sample analysis.
• Test result – Result of the sample tests, which includes:
  • the name of the determinand or parameter the sample was tested for 
  • the laboratory test result which may include a prefix of < (less than) or > (greater than)
  • unit of measurement, e.g. mg/L, NTU, CFU/100mL.

See the Parameters and determinands file for acceptable names and units of measurement for test results, you can also view the MAVs and aesthetic values of determinands in this file.

The supply component ID can be found in your supply information dashboard after logging into the Authority’s self-service online portal, Hinekōrako.

We are testing a webform for medium supplies reporting to us quarterly from 2025 and are planning to design a webform which will simplify annual reporting for small supplies. This webform will also allow back-dated reporting in case you did not report in prior years, though the Rules came into effect from the 2023 calendar year.

There are alternatives to reporting which are currently available. For more information on how to report using these alternatives, refer to the Reporting Guidance section below.

Water suppliers need to provide annual compliance information to the Authority within 40 working days of the end of each calendar year. This date will fall on a weekday near the end of February every year. Small drinking water suppliers only need to report Rules compliance to the Authority once a year. Note: This requirement changed from 2025 onward, six-monthly reports are no longer required.

The method of collecting, transporting and analysing a sample is important to make sure the test results are accurate. For water samples that require laboratory analysis, rule G8(a) requires suppliers to have them analysed by a laboratory accredited by IANZoutbound for the specific test being ordered. This rule ensures the water supplier, consumers and the Authority have confidence that the result of the testing is accurate.

For example, laboratories that analyse water samples for E. coli and total coliforms must demonstrate to IANZ that they have the capability and equipment to undertake these tests in a way that will provide an accurate result. If the results are not correct, it could mean a water supplier is taking action to manage contaminated water when the water is actually safe, or that the supplier thinks the water they are supplying is safe when it is not.

Rule G8(b) requires you to follow the laboratory’s instructions for collecting samples to avoid possible contamination. Instructions may include using a sterile container when sampling microbiological samples, using certain bottles containing preservatives, and sterilising and flushing sampling points.

Once the sample is collected, it needs to be traceable so that the supplier and the Authority can understand what the test results mean for the supply when the laboratory reports the results back to you. Rule G6 requires samples to be labelled with your supply’s unique ID for the source abstraction point, treatment plant or distribution the sample was taken from and the time and the date the sample was collected. Suppliers should also assign a unique sample ID to each sample to distinguish between each of them.

When transporting samples, you will need to follow rule G7 to ensure the water samples don’t heat up or become frozen before reaching the lab. This rule ensures the quality of microbiological samples by reducing the risk of bacterial die-off over time or, in some cases, bacterial growth.

If you are using IANZ accredited on-site laboratory equipment, delays getting the sample analysed should be minimised and the risk of the sample getting too hot are significantly reduced.

Some monitoring, such as for turbidity and chlorine, can be done by a water supplier using handheld or desktop analysers. These instruments can become inaccurate over time and must be calibrated or verified as per manufacturer’s instructions to maintain data quality as required by rule G9.

Suppliers must ensure that the people who work on the drinking water supply know what they are doing, and must determine if someone is suitably qualified, trained or experienced to meet rule G10. Water suppliers should ask people they engage to work on their supplies about their qualifications and experience. For example, if someone is engaged to test a backflow device, it would be useful to check that they have completed a course in backflow assessment and testing.

A hygiene code of practice outlines a water supplier’s expectations about how people working on their supply will protect the supply from contamination, as this is a high-risk activity which, when done poorly, can lead to outbreaks of enteric disease. Drinking water should be thought of in the same way as a food establishment. Cleanliness is key. This document does not need to be long but must include the following considerations as listed in rule G11.

• How personal hygiene will be maintained, e.g. washing hands after using a toilet or use of sterile gloves.
• Preventing people with gastrointestinal illness (suspected or confirmed) from working on the water supply.
• How work sites, materials and tools will be protected from contamination, e.g. cleaning tools with 1% sodium hypochlorite before using them on the drinking water supply and not using tools that have been used on wastewater systems.
• How all reasonable steps will be taken to minimise exposure of the supply to contamination during any activity.

You must test for E. coli and total coliforms in any source water at each source water abstraction point, along with specific chemicals according to the type of source.

Arsenic, boron, nitrate and manganese are commonly found in surface and groundwater sources. Cadmium, copper, and lead are metals which can leach out of roofing materials into a roof water supply. Testing for these chemicals in your source water help you understand whether these chemicals present a risk to your supply. The tests required in the S1 Rules module are standard tests that can be conducted by many accredited laboratories. Often laboratories will offer a suite of drinking water tests for a fixed fee or you can order individual tests. For more about accredited laboratories, go to the General Section ‘What is IANZ accreditation? G8’.

Read here for more information on chemical contamination. 

E. coli are bacteria that indicate faecal contamination. If they are found in a water sample, this indicates that the sample is contaminated with the faeces of a person, animal or bird, and therefore it is expected that bacteria and other pathogens that can cause serious illness will also be in the water. Some of these pathogens include bacteria like Campylobacter and Salmonella, viruses like norovirus, and protozoa like Cryptosporidium or Giardia. These pathogens along with E. coli can enter a water source, for example, through runoff or wastewater discharges near the surface or groundwater abstraction point, or from animal droppings on the roof collection area.

Total coliforms are a group of bacteria that live in the wider environment, e.g. on decaying vegetation. If total coliforms are found in a water sample, it indicates that bacteria are present in the water.

You can use the results of both tests together to assess the quality of water being treated and provided. If a sample result is positive (e.g. 1 per 100 mL or more) for E. coli, it tells us that the water is contaminated with faeces and is not safe to drink without treatment. When a result is positive for total coliforms but negative for E. coli, it indicates the water is contaminated with bacteria but they are not from the faeces of humans, animals or birds.

Total coliforms are normal in most source waters but should not be present in deep groundwater. If total coliforms are present in deep groundwater, then it may mean the aquifer has been compromised or your bore is abstracting water which is influenced by surface water, like a river or rainfall, or another bore close by which has been contaminated.

If you find E. coli and total coliforms in source water, it’s a good idea to keep track of these in a spreadsheet or logbook so you can know if something has changed with your source water. If you find very high amounts of E. coli, you may need to investigate the area around your source water for a source of contamination. Both live and dead animals can release large amounts of disease-causing bacteria into source water. If you find live or dead animals are regularly contaminating your source water, you will need to implement some risk mitigation strategies, like fencing off your bore, removing vegetation and branches overhanging your roof or removing a dead animal from near your source water abstraction point.

As a water supplier, you may be aware of other substances, including chemicals, that have the potential to present a risk to the supply. This risk assessment should be part of your drinking water safety plan and could be based on known land uses near the water source or information that a district or regional council has provided. For example, some water sources may be naturally high in iron due to geological factors, or the source may be near an agricultural area that uses particular pesticides.

Some chemicals are only a risk to certain sources and must be dealt with in a bespoke manner. For example, where fireplaces are present, soot can deposit on roofs where there are nearby chimneys, particularly in colder months. Rain can wash the soot into your roof water supply. Soot contains carcinogens like benzo(a)pyrene. If soot is deposited on your roof, that means benzo(a)pyrene presents a risk to your supply and you must test for it according to rule S1.3. If your water smells like smoke, or tastes like char, you need to ensure you manage this risk. This may include measures like installing a first flush diverter, installing treatment which specifically removes this (e.g. activated carbon filters) or other measures to clean your roof regularly.

Cyanobacteria, or blue-green algae, are a cross between bacteria and algae. Cyanobacteria can be a problem because some species can produce toxins called cyanotoxins which can make people ill. It is not clear what causes some cyanobacterial species to produce toxins. Cyanobacteria usually don’t produce toxins all the time but when they do it can be very harmful.

Cyanobacteria can form as a colony that appears as a large cloud within a water column, and this is called planktonic cyanobacteria. Indications of planktonic cyanobacteria include water discolouration and a lack of clarity of the water.

Cyanobacteria can also form as mats on the floor of a river or lakebed and then are known as benthic cyanobacteria. Benthic cyanobacteria look like a black or brown slimy or furry layer on rocks in a river.

Cyanobacteria like warm water, so planktonic blooms or benthic mats generally occur over the spring/summer/autumn period.

If the source water cannot easily be accessed to assess cyanobacteria risk, laboratory testing could also be used to determine cyanobacterial cell counts. Seek advice from an accredited laboratory if using this approach.

For photo examples of what the benthic and planktonic cyanobacteria can look like, visit LAWA’s Toxic Algae factsheetoutbound.

Any chemicals determined to be a risk, or any chemicals detected at above 50% of the MAV, such as those required in S1.1 or S1.2, must be tested at least annually until three consecutive results are less than 50% of the MAV. There is flexibility in how these samples are taken. A supplier can take all the samples in a year or even in one month but must ensure that three consecutive samples are less than 50% of the MAV before they stop sampling. For example, if you take the first sample and it is less than 50% of the MAV, you may choose to take the remaining two samples quite soon after that to meet the requirement quickly.

However, once a determinand is known to have exceeded 50% of the MAV, or is known to be present in the area, it becomes a known risk and should be included in your risk management plan. Continuing to sample the determinand alongside the required chemicals is recommended.

If a chemical test of a source water sample exceeds the MAV, while it is not technically drinking water, it still indicates a contamination risk to drinking water provided to consumers. The Rules require monitoring of elevated determinands to increase to at least annually until three consecutive results are below the MAV. At this point you can return sampling frequency to once every three years. However, once a determinand is known to have exceeded 50% of the MAV, it becomes a known risk and should be included in your risk management approach.

If a chemical is above the MAV in the water source, you must make sure it is not present in the drinking water after treatment. Unless the treatment plant has specific treatment processes to remove the chemical, it is likely that the MAV exceedance will be present in drinking water too. Any non-compliance with the Standards must be managed (see s 22 of the Act).

If more than one source is used, samples need to be collected from each source separately. This is because you need to know the quality of each source in case only one source is being used at any particular time. If a supply uses roof water and a spring/stream or other source, all sources need to be sampled and tested separately.

Cyanobacteria risk assessment can be simple if there is no risk or low risk.

• Roof water is not at risk of cyanobacteria.
• Groundwater and springs are not typically at risk of cyanobacteria unless there is a nearby lake or river which has been known to have cyanobacterial blooms.
• Surface waters can be more complex to assess whether cyanobacteria (and therefore cyanotoxins) present a risk. Surface waters can be low risk if you or others have tested for cyanobacteria in source water and found nothing, or where visual inspections have shown no evidence of cyanobacteria growth.

Where a surface water source, like a lake or river, has been known to have cyanobacteria present, risk can be more complex to assess. You may need to consult local or regional professionals and experts to better understand your source.

For lakes and ponds generally, where cyanobacterial blooms and extensive benthic cyanobacterial mats have been confirmed, water taken from these sources is high risk for cyanobacteria and cyanotoxins. If cyanobacterial blooms in lakes and ponds have not been confirmed or where benthic cyanobacteria has not been confirmed, this can change. You’ll need to continue monitoring your source for signs of growth according to rule S1.5.

Regional councils will generally undertake cyanobacteria testing for recreational purposes in certain lakes and streams that are at risk for cyanobacteria and cyanotoxins. Territorial authorities with drinking water supplies also test for cyanobacteria regularly and may hold information on your source water. This information can be useful if they monitor your source water.

If you find evidence of cyanobacteria in your source water, you must determine if there is a risk to consumers from cyanotoxins. Assessing a supply for cyanotoxin risk is complex and will likely require assistance from an experienced professional advisor or laboratory that undertakes cyanobacteria/cyanotoxin analysis. It is important that the water supplier advises consumers if there is a risk of cyanobacteria/cyanotoxins contaminating the supply. Any complaints of skin irritation or gastrointestinal illness should be taken very seriously, as this can also be a sign that there are cyanotoxins in the supply. There are treatment options available.

You must either stop supplying water from that source or issue a do not drink notice . The presence of cyanobacterial blooms or extensive benthic cyanobacterial mat coverage is the most obvious sign that you need to do something. You have options when you think your supply is at risk, as outlined in rule S1.5(c).

If you think the supply is at risk from cyanotoxins, you need to arrange for laboratory testing and expert advice will be required. Installing treatment is an option to remove cyanotoxins from drinking water. However, it is often a better option to find an alternative water source that doesn’t have a cyanotoxin problem.

Removing cyanotoxins can be challenging as treatment can be expensive and there is a risk of breaking open the cyanobacteria cells and potentially releasing cyanotoxins. Treatment includes nanofiltration, reverse osmosis or granular activated carbon filters. It’s important that the treatment is specifically designed and validated to remove cyanotoxins. You can generally find out more from the manufacturer providing the treatment equipment. If an alternative source is available, switching to a source that has a lower risk of cyanotoxins may be more effective than installing treatment.

Cyanobacteria can often be detected in drinking water by consumers due to distinctive taste and odours they can generate. A musty or earthy smell and taste in the water and complaints about taste and odour are often the first indication of a cyanobacteria problem. It is therefore important to record and investigate any taste or odour complaints as they can help detect cyanobacteria issues.

Not all taste and odour problems are caused by cyanobacteria and expert advice may need to be sought. The same treatment processes that treat for cyanotoxins are generally effective for taste and odour compounds too, that is nanofiltration, reverse osmosis or granular activated carbon filters. The manufacturer of the treatment equipment will be able to give you more information on effectiveness for taste and odour treatment.

E. coli are bacteria that indicate faecal contamination. If they are found in a water sample, this indicates that the sample is contaminated with the faeces of a person, animal or bird. It is expected bacteria and other pathogens that can cause serious illness will also be in the water. Some of these pathogens include bacteria like Campylobacter and Salmonella, viruses like norovirus, and protozoa like Cryptosporidium or Giardia. These pathogens along with E. coli can enter a water source, for example, through runoff or wastewater discharges near the surface or groundwater abstraction point or from animal droppings on the roof collection area.

Total coliforms are a group of bacteria that live in the wider environment, e.g. on decaying vegetation. If total coliforms are found in a water sample, it indicates that bacteria are present in the water. 

If treatment is ineffective then this contamination can carry through to consumers drinking water. This indicates there is a pathway for pathogens to enter the drinking water.

Treated water can be sampled as it leaves the treatment plant or in a treated water storage tank at the treatment plant. The sample needs to be representative of water leaving the treatment plant, i.e. there are no further treatment steps between the sample location and the distribution network.

If a sample result is positive for E. coli, you must take immediate steps to protect consumers and prevent them from consuming the water and becoming unwell. You can do this by advising all consumers to boil the water before they drink it.

You must notify the Authority if a sample of treated water is positive for E. coli as this breaches the Standards and presents a public health risk. Laboratories will also notify the Authority separately if drinking water test results are positive for E. coli.

Advising consumers to boil all drinking water is only a short-term measure. You must investigate to find the cause of the E. coli contamination and fix it (see ss 21(2) and 22(2) of the Act), including: 

• if the supply has a treatment system, check it is working properly
• if a suitable treatment system is not installed, find
• continue testing for coli and total coliforms as you investigate the contamination

If treated water stops testing positive for E. coli before a reason is found, you still need to look for the cause so that you can remedy the issue and protect consumers from recurrence.

If a sample result is positive for total coliforms but does not contain E. coli then bacteria are entering the treated water. You don’t have to advise consumers to boil the water but it is still important to check that the treatment system is working. You should still look for the cause so that you can remedy the issue. If total coliforms are found, bacteria still entered the water and the water could be more seriously contaminated in the future.

Turbidity is a measurement of water clarity. At high levels (more than 5 NTU), the water has a “muddy” or “milky” appearance. “Crystal-clear” water usually has a turbidity of less than 1 NTU. At low levels (less than 1-5 NTU), turbidity can only be detected by instruments.  

Turbidity should be less than 5 NTU for UV disinfection to work well and to maintain high quality water for the consumer. Filtration typically can achieve turbidity well below 5 NTU. High turbidity (>1-5 NTU) in treated water indicates that something has changed in the system, such as contamination of the source or an issue in the treatment process. It’s important to regularly maintain your filters to ensure they can consistently reduce turbidity of source water.

If a chemical test exceeds the MAV, you must report it to the Authority with your proposed response. For notification guidance, refer to our website (Notify Taumata Arowai | Taumata Arowai) and Hinekōrako guidance (Create and submit a supply notification). Laboratories must notify you if a treated water result from your supply is above the MAV. The laboratory will also notify the Authority separately. Responses to chemical exceedances will vary depending on the chemical and could range from informational consumer advisory notices to a do not drink notice and providing an alternative supply (such as a water tanker). You could also provide bottled water so people have enough to drink.

Testing for other determinands will depend on your supply. If you are aware of other substances that could present a risk to the supply, you need to identify them and address the risk in your drinking water safety plan. Substances may occur naturally in the source water (e.g. arsenic), be introduced to source water through human activities (e.g. via environmental discharges – permitted or accidental – or from typical land use activities) or they may be a chemical that is used in a treatment process (e.g. such as pH correction).

If a contaminant in the source water exceeds 50% of the MAV, it is a risk to the supply that must be monitored in water leaving the treatment plant to make sure its levels do not exceed the MAV in drinking water.

You may choose to first test for a chemical in source water to identify whether it is a risk to your supply. It is good practice to take a sample of treated water at the same time you test your source water for a chemical determinand so you know whether your treatment plant removed it. Chemical testing can be expensive, so it’s important to weigh up the benefits versus cost of testing chemicals in small water supplies.

If a substance / determinand presents a risk to the supply, you must sample at least every three months until three consecutive samples have a result of less than 50% of the MAV (after this, the Rules no longer require sampling to continue unless the determinand becomes a risk again). If the first two samples are less than 50% of the MAV but the third is more than the MAV, sampling needs to begin again from the first sample.

Once a determinand is known to have exceeded 50% of the MAV or is being added as part of a treatment process, it becomes a known risk and should be included in your risk management approach. Rule T1.2 is intended to provide flexibility around an individual supply’s circumstances. You might sample three days in a row or once per month over the next three months.

Remember that bacteria and nitrate MAV exceedances present an immediate public health risk, whereas other chemical determinands present a risk over time. Most chemicals are not commonly found in drinking water in excess of their MAV.

Filtration of a water supply removes particles of a certain size from water. This is important for downstream treatment like UV to ensure that treatment is effective. Filtration can also make the drinking water more aesthetically pleasing to drink, reducing things like turbidity, grit and iron from water.

Chemicals can be attached to particles or freely floating (i.e. dissolved) in the water. Most filters can remove chemicals attached to particles but only certain types of filters can remove chemicals dissolved in the water.

There are four types of filtration to meet treatment requirements for the small drinking water supply rules. Each supply is unique so you are advised to contact a filter manufacturer to determine the best system for your .

Cartridge filters are the most common for bore and roof water supplies and act as very fine sieves which are contained in a protective housing. The pore size of the filter is the size of the holes in the filtration cartridge. They are simple to maintain and replace when needed.

Back-washable media filters use a media, like sand, either in a big tub or in an enclosed vessel to remove dirt particles from water. Generally, these are used when a water source has elevated or intermittently elevated turbidity like surface water. Eventually the filter media gets clogged, at which point the water flow is reversed to wash the dirt particles out. A valve is opened to divert the dirty water to waste, and the filter is cleaned and ready to be put back into use.

Slow sand filters have a sand bed with an active microbial layer on the top of the sand. The microbial layer consumes the organic material that the water deposits on it, leaving filtered water to trickle slowly through the sand layer. Slow sand filters can be run in remote locations with no pumps.

Membrane filters consist of fine tubes or membranes with very small pores or holes in them. Membrane filters are very good at filtering water with particles and can have smaller pore sizes than cartridge. Water pumped through the pores and any dirt or other particles are left on the outside of the membranes. Membrane filters have a high energy use and higher level of maintenance compared to other filtration options. An important maintenance task is to clean the membranes. This involves chemicals that present health risks to operators which must be managed, and waste products that must be disposed of safely, generally to a wastewater sewer.

Groundwater often has lower turbidity than surface water sources. Deeper bores usually have more stable turbidity than shallower bores, though this can depend on the characteristics of the bore and the bore infrastructure. Because of this, if your water is abstracted from deeper than 30 metres below the ground surface, filtration is not compulsory.

However, deep groundwater can have high turbidity too, so it is important to monitor the turbidity in the source water. If turbidity is an issue in a deep groundwater bore, filtration may need to be installed to allow effective UV treatment, or it may be a sign the bore infrastructure has degraded significantly and may require maintenance.

Cartridge filters are designed to have water pushed through them so it is important to ensure any pumps are upstream of the cartridge filters. If water is to be pumped somewhere after cartridge filtration, the water coming out of the filters must be discharged into a tank from which the water can then be pumped. This provides a physical separation between the filters and the pumps downstream.

UV treatment works by damaging the DNA in microorganisms, preventing them from multiplying and infecting people. To be effective, the UV light inside the UV unit must be strong enough to inactivate pathogens. This is known as UV intensity. UV intensity is measured in energy output in millijoules (mJ) over an area measured in square centimetres (cm²), resulting in the unit mJ/cm². Essentially, a UV dose of 40 mJ/cm² is required to ensure bacteria are inactivated. This dose is also effective for other pathogens like protozoa.

The science and engineering that are used to ensure UV units work effectively are complex and requirements have been standardised. Your UV units need to be certified to one of several international standards and operated according to the manufacturer’s instructions to ensure the UV unit inactivates pathogens. Check with the manufacturer to ensure that a UV unit meets the required dose and certification before purchasing.

A distribution system is generally the network of pipes and storage tanks that transmit drinking water to consumers and normally starts as water leaves the treatment plant. A distribution zone is all or part of a distribution system which contains water of a similar character, often defined as a bounded geographic area. Every drinking water supply with a distribution system has at least one distribution zone. Supplies that provide water over a large area may have more than one distribution zone so it is important to make sure each one is tested.

E. coli are bacteria that indicate faecal contamination. If they are found in a water sample, this indicates that the sample is contaminated with the faeces of a person, animal or bird. It is expected that bacteria and other pathogens that can cause serious illness will also be in the water. Some of these pathogens include bacteria like Campylobacter and Salmonella, viruses like norovirus and protozoa like Cryptosporidium or Giardia. These pathogens along with E. coli can enter a water source, for example, through runoff or wastewater discharges near the surface or groundwater abstraction point or from animal droppings on the roof collection area. E. coli can enter drinking water through storage tanks. Holes in the tank, hatches, air vents and overflows can allow E. coli to enter the water. E. coli can also be drawn into pipes through pipe breaks and leaks.

Total coliforms are a group of bacteria that live in the wider environment, e.g. on decaying vegetation. If total coliforms are found in a water sample, it indicates that bacteria are present in the water.

If treatment is ineffective or the distribution network is not secure (e.g. pipe breaks, treated storage contamination) then this contamination can carry through to consumers’ drinking water, and indicates there is a pathway for pathogens to enter the drinking water.

If a sample result is positive for E. coli, you must take immediate steps to protect consumers and prevent them from becoming unwell from consuming the water. You can do this by advising all consumers to boil the water before they drink it.

You also must notify the Authority if a sample of treated water is positive for E. coli as this is in breach of the Standards and is a public health risk. Laboratories will also notify the Authority separately of drinking water test results that are positive for E. coli.

Advising consumers to boil all drinking water is only a short-term measure. You must investigate to find the cause of the E. coli contamination and fix it (see ss 21(2) and 22(2) of the Act). You must take the following steps: 

• if the supply has a treatment system, check it is working properly
• if a suitable treatment system is not installed, consider finding a suitable system and installing it 
• investigate for breaks, damage or recent changes to the distribution network
• inspect storage reservoirs for ingress of vermin
• continue testing for coli and total coliforms as you investigate the contamination.

If treated water stops testing positive for E. coli before a reason is found, it is important to still look for the cause so that you can remedy the issue and protect drinking water consumers.

Once the source is identified, consider flushing the network and adding a dose of chlorine through the distribution zone (if chlorine treatment is available to use). Although not required in level 1 rules, chlorine provides a useful response option for contamination events. You are advised to seek advice from a trained professional when adding chlorine to a supply.

When testing the distribution network, it is important to gather representative samples from across the network. It is also important to check areas more likely to have issues such as the far ends of the network where sediment may accumulate. This ensures consumers are still receiving safe drinking water regardless of where they are connected to the supply. Samples could be taken from a purpose-built sampling tap or inside a building. If sampling from private or public property, water quality issues may arise from internal plumbing. Check with the laboratory for sampling techniques that minimise risk from contamination at any sample point, such as disinfecting the tap and letting the tap run before taking the sample.

While the rules for small drinking water supplies do not require testing of other determinands, you still need to consider the risks of the supply and how to manage them in your drinking water safety plan. For example, a supplier may need to undertake additional testing to manage the risk of lead, plumbosolvency or chlorate issues in the distribution network, depending on the treatment and materials used in the supply. Microbiological testing in the network uses a different sampling methodology to chemical testing. Check with the laboratory conducting the analysis for specific test instructions.

Backflow can occur when there is a drop in pressure in the distribution system and water from an open tap is drawn back into the network. The pressure drop could be caused by a pipe break or the fire service pumping water from a hydrant to put out a fire. Water could be drawn back into the network, for example from a hose left filling a swimming pool or in a bucket being used to make a pesticide spray. Backflow is a real risk to small drinking water supplies and there are many examples of backflow occurring in these supplies resulting in risks to consumers.

While the Building Act does require some levels of backflow prevention on properties, these are to protect the building and not necessarily the water supply the building is connected to. Water suppliers need to undertake their own backflow risk assessments to protect the water supply.

Contamination can also occur from a cross connection. This is where a pipe that is carrying a substance other than drinking water is connected into the distribution system. It may occur within a domestic premises or farm rather than within the supply piped network. While unlikely, it does happen and can be a serious risk to those drinking the contaminated water. Examples of this include connection to untreated water from a domestic roof supply, stock water or an industrial chemical.

To assess backflow risk, you need to investigate the distribution zone for high-risk consumer activities. Activities presenting backflow risks include swimming pools, stock troughs, private water sources and hairdressing. Water New Zealand has produced a guide Boundary Backflow Prevention for Drinking Water Supplies Code of Practice to assist you with this task.

There is some level of backflow risk from every connection to a water supply, including household connections, and best practice is to install some form of backflow protection at every connection. This is not always practical or achievable so the focus should be on the sites where there are medium or high risks.

When you have assessed where in the distribution system backflow risks are, you need to compile a register of sites where there is a medium or high backflow risk. The register may include information on the location where the risk exists, the property owner and contact details, details of the activity that is responsible for the risk, whether there is a backflow protection device installed at the premises, and what type of device it is.

There are three main types of backflow protection device.

• A reduced pressure zone device (RPZD) is used on the highest risk sites. This type of device can be tested to see if it is working.
• A check valve usually has a flap that closes when water flows in the direction it is not meant to flow. Check valves generally cannot be tested to see if they are working. Small double check valves can be installed at the point of supply (toby) for domestic households and simple check valves can be attached to taps.
• An air gap is a permanently mounted gap between the delivery pipe and the maximum water level of a tank and can be used where the network delivers water to consumers’ personal water storage tanks. An air gap needs to be inspected to make sure that it is still in place and has not been undermined by tank configurations such as an overflow outlet that is too high.

The Authority does not have a specific test or framework to determine who is a suitably trained or experienced person. However, suppliers need to ensureIf someone is engaged to test a backflow device, it would be useful to check that they have completed a course in backflow assessment and testing. This can include an Independently Qualified Professional (IQP).

The Varying Population rules are addressing two changes to supply risk when populations increase. Small drinking water supplies are designed for their normal population size, so if the population increases significantly and water demand increases, the water supply characteristics may change. This could lead to water not being treated sufficiently or breaks to occur in the supply.

When water supplies have limited water treatment and water quality monitoring, the consequence of things going wrong can rise if the population increases for a short period of time, i.e. more people could get sick. This may occur when more than 100 people use your water supply for a limited period.

Testing for microbiological contaminants gives you an understanding of the water quality being consumed by the increased population, and an opportunity to detect and address any issues occurring during the time of increased demand on the supply.

If you know that your population increases around public holidays, especially if the supply serves a campground or group of holiday houses, or if you have recurring events that bring in significant numbers of visitors such as annual festivals, you should plan to use the Varying Population rules module and include this in your drinking water safety plan.

You should also keep up to date with news in the community for any one-off events, as these may also trigger the need to follow one of the Varying Population rules.

You are only required to increase monitoring the week prior to the population exceeding if the population increase is predictable. If the population increase was not predictable, but you started sampling according to the Varying Population rules as soon as the population increased above the limit, you can still consider yourself compliant.

Reporting on monitoring rules must be provided to the Authority in an approved form.

A webform for small drinking water suppliers will be developed in time for annual reporting on the 2025 calendar year.  The webpage will have prompts to make reporting easy. We will provide an update to suppliers when the webform is available.

If you use software such as Infrastructure Data or WaterOutlook, you may be able to automatically report via a web-based Application Programming Interface (API).

An excel spreadsheet template is also available for small drinking water suppliers, found in Section 2. How to report in the Reporting Guidance. 

As a small supply following level 1 rules, you only need to report against monitoring rules once a year. This is reported within 40 working days after the end of a calendar year. The table below shows the rule numbers and the related requirements which need to be reported on. For example, for rule S1.1, S1.1-a.i refers to the requirement to sample for E. coli in your groundwater or surface water source every quarter of the year.

Reminder: You only need to report against rules and reporting rule IDs that apply. For example, if you do not have a roof water source for the supply, do not report against roof water rule S1.2.

No, only supplies with continuous monitoring used to demonstrate compliance need to follow these continuous monitoring requirements.

For determinands which require a sampling frequency of every three years, compliance may be achieved for the calendar year if a sample has been taken in the three calendar years prior to the report being submitted.

If you did not consider that there were any risks to your supply which required samples to be taken to meet rules S1.3 or T1.2, then you should report these rules as compliant. If you have identified determinands that could be a risk in the supply, but these were not tested for, then this would be non-compliant with these rules.

• Example “True” scenario: A supplier has tested for lead and copper twice annually. These were the only determinands identified to pose a potential risk to consumers in their drinking water safety plan. All four test results obtained have been submitted as samples under rule T1.2.
• Example “False” scenario: A supplier has identified in their drinking water safety plan several determinands (lead, copper, zinc) which may pose a risk to consumers. The supplier has not tested for the determinands during the year. No test results would be submitted as none were taken.

If you took every sample that a rule requires, regardless of the results, you are compliant with the rule. If the sample result exceeded the MAV, then this is a safety risk that needs to be managed and needs to be notified to the Authority.