Small self-supplied buildings supply
Information for drinking water supplies serving 26 to 100 people in up to 10 buildings on one property or adjacent properties with common ownership.
Key things you need to know as a provider of a small self-supplied buildings drinking water supply can be found on this page.
Am I a small self-supplied buildings supplier?
You are a small self-supplied buildings supplier if:
- your supply normally serves a population of 26 to 100 people in up to 10 buildings
- the buildings served by your supply are either all on one property or split across adjacent properties with a common ownership arrangement.
A common ownership arrangement is where adjacent properties on separate titles are effectively managed as one property. Examples include:
- a residential body corporate where multiple people own unit titles but manage the common property together
- Māori land which may be artificially divided into separate titles but operates in effect as one unit
- a rural school where the Ministry of Education owns nearby neighbouring houses used for staff accommodation that are on separate legal titles
- commercial operations that own multiple property titles that are operated together as one industrial site.
Arrangements that are not common ownership include:
- a farm supplying water to a schoolhouse on a neighbouring property
- a factory supplying water to a neighbouring house that’s on a separate legal title and is not owned by the factory.
Not you? Find out what type of supplier you are here.
Register with us
If you're a new supplier, or an existing supplier who was registered under the previous regulator but has not yet registered with us, you'll need to register your supply with us on our Hinekōrako supply portal. The portal enables you to share important information with us about your supply.
Head to our registration page for more information and to access Hinekōrako.
Drinking Water Quality Assurance Rules or Acceptable Solution?
Providers of small self-supplied buildings supplies have two options for complying with the Water Services Act 2021outbound and ensuring safe drinking water is delivered to their community.
You can either prepare a drinking water safety plan (DWSP) and follow the Drinking Water Quality Assurance Rules (see below) or use a readymade option called an Acceptable Solution. If you choose the Acceptable Solution, you will not need to prepare a DWSP or follow the Drinking Water Quality Assurance Rules.
Information about the Acceptable Solution is further down this page and you can jump to it here.
Drinking water safety plan (DWSP)
Preparing a drinking water safety plan is a risk management process that aims to ensure a safe, reliable and resilient supply of drinking water to your community. If you are establishing a new supply or registering an existing supply, you will need to provide a DWSP unless you adopt an Acceptable Solution (see above).
What should be in a DWSP?
Your DWSP records the hazards and risks to your drinking water supply and how you will manage them to ensure that drinking water is safe. Your plan must:
- be proportionate to the scale and complexity of, and the risks that relate to, your drinking water supply
- identify any hazards that relate to your drinking water supply
- assess any risks associated with those hazards
- identify how those risks will be managed, controlled, or eliminated to ensure that the water you supply is safe and complies with the legislative requirements of the Water Services Act 2021 outbound
- identify how the DWSP will be reviewed on an ongoing basis, and how its implementation will be amended, if necessary, to ensure that the drinking water you supply is safe and complies with legislative requirements
- identify how your drinking water supply will be monitored to ensure that drinking water is safe and complies with legislative requirements
- include procedures to verify that your DWSP is working effectively
- include a multi-barrier approach to drinking water safety that will be implemented as part of the DWSP
- include a source water risk management plan if required
- if your supply includes reticulation, require, and provide for the use of, residual disinfection in the supply unless an exemption is obtained
- identify how you will meet your duty as a supplier to ensure that a sufficient quantity of drinking water is provided
- identify how you will respond to events and emergencies in relation to your supply
- comply with the relevant requirements of the Drinking Water Quality Assurance Rules (the Rules).
Some registered suppliers may not need to prepare a DWSP
You may be able to comply with an Acceptable Solution (see blue panel above). If this is the case, you need to decide between the following options in relation to each of your supplies:
- Option 1: prepare a DWSP (including a source water risk management plan) that complies with the Water Services Act 2021outbound, and follow the Rules or
- Option 2: comply with an Acceptable Solution, which have been developed for particular supply types and circumstances.
If an Acceptable Solution doesn't apply or you choose not to use one, you must complete a DWSP.
Note: If you meet the criteria you can switch between following the Rules and following an Acceptable Solution. However, you will have to update your registration details in Hinekōrakooutbound and submit reports for the period that you are following the Rules. If you are changing from an Acceptable Solution to following the Rules you will also have to complete and upload a DWSP.
Source water risk management plan
A source water risk management plan is part of your DWSP, unless your supply doesn’t have a source (for example, you receive water from another supplier). It sets out how hazards and risks in your source water will be managed. One step in the development of your plan will be engaging with local authorities to understand the risks to your water source.
A source water risk management plan must:
- identify any hazards that relate to the source water, including emerging or potential hazards
- assess any risks that are associated with those hazards
- identify how those risks will be managed, controlled, monitored, or eliminated as part of a DWSP
- include a description of the land surrounding the source water or the groundwater catchment
- have regard to any values identified by local authorities under the National Policy Statement for Freshwater Management (made under the Resource Management Act 1991) that relate to a freshwater body that you use as a source of your drinking water supply.
Guidance and template
We've prepared additional guidance and a template you can use to submit your DWSP. It's not mandatory to use the template and you can submit your plan in a different format as long as it addresses each of the elements described under ‘What should be in a DWSP?’ above.
Guide to uploading your DWSP to Hinekōrako outbound
Rule types, reporting, and compliance periods
Monitoring rules
Monitoring rules set out requirements to monitor the quality of source water and treated water. They cover determinands and parameters that need to be either continuously monitored or regularly sampled. Monitoring rules have compliance periods of 1 day, 1 month, 3 months, or 1 year, which typically depends on the frequency of monitoring required in the rule.
1-day compliance periods
A monitoring rule which requires a determinand or parameter to be continuously monitored or monitored daily, irrespective of the period of the day that the supply is operating, has a compliance period of 1 day, i.e. 24 hours (midnight to midnight).
1-month compliance periods
A monitoring rule which requires a determinand or parameter to be monitored on a monthly or weekly basis, e.g. 2 per week, 8 per month, etc., has a compliance period of 1 month.
3-month compliance periods
A monitoring rule which requires a determinand or parameter to be monitored at least every 3 months has a compliance period of 3 months.
1-year compliance periods
All other monitoring rules have a compliance period of 1 year.
Note: Where monitoring occurs at least every 3 years or at least every 5 years, the rule must be reported annually. It will be compliant if the monitoring was not due that year or if the monitoring was due and was undertaken.
Assurance rules
Assurance rules cover activities that water suppliers need to undertake, for example the preparation of a backflow prevention programme or a distribution zone sampling plan. Assurance rules are used to indicate whether water suppliers undertake activities that contribute to the provision of safe drinking water.
Assurance rules have a compliance period of 1 year.
Non-reporting rules
Some rules are designated as non-reporting rules and water suppliers are not required to report on their performance against those rules, though they are still expected to comply with the requirements of the rules. Non-reporting rules have no compliance period as they do not have to be reported on.
The rules that apply to this type of supply are listed below. You can download the complete Drinking Water Quality Assurance Rules here.
See also this rules guidance for small supplies.
General Rules
The following Level 1 General Drinking Water Quality Assurance Rules apply.
Rule G1 – reporting requirements (assurance rule)
Drinking water suppliers following level 1 Rules modules must report annually:
(a) whether they complied with each monitoring rule requirement; and
(b) the number of quarters for which each monitoring rule requirement was not complied with during each calendar year; and
(c) the supply component ID, sample ID, sample date, and test results for all samples analysed by a laboratory during the year; and
(d) within 40 working days of the end of each calendar year; and
(e) in an approved form.
Compliance period: 1 year
Rule G6 – sample labelling (assurance rule)
All samples collected from drinking water supplies for monitoring that are analysed by laboratories must be labelled with the unique source, treatment plant, distribution zone, or Water Carrier Service identifier allocated by the Water Services Authority – Taumata Arowai, to show where the sample was collected from and the time and date that the sample was collected.
Compliance period: 1 year
Rule G7 – sample delivery (assurance rule)
Drinking water suppliers must take reasonably practicable steps to ensure that samples for E. coli, total coliforms, or other microbiological contaminants are delivered to a laboratory within 24 hours of the sample being collected, and at a water temperature that is no higher than the water temperature at the time of sampling but above zero degrees Celsius.
Compliance period: 1 year
Rule G8 – sample analysis (assurance rule)
All water samples that require laboratory analysis and are used to demonstrate compliance with these Rules must be:
(a) analysed by a laboratory accredited by IANZ for the type of analysis being undertaken; and
(b) collected according to any instructions and specifications provided by the laboratory.
Compliance period: 1 year
Rule G9 – sampling equipment (assurance rule)
Equipment used for the analysis of single samples (grab samples) by drinking water suppliers, to demonstrate compliance with any rule, must be calibrated/verified in accordance with the instrument manufacturer’s specified procedures and frequency.
Compliance period: 1 year
Rule G10 – worker experience (assurance rule)
All work (planned or unplanned) on a water supply must be completed by suitably trained or experienced personnel.
Compliance period: 1 year
Rule G11 – worker hygiene (assurance rule)
Drinking water suppliers must prepare a hygiene code of practice for people working on a water supply which must include:
(a) maintenance of personal hygiene at all times; and
(b) prohibition of people working on a water system who are experiencing any gastrointestinal illness; and
(c) protection of the work site, materials, and tools from contamination; and
(d) how all reasonable steps will be taken to minimise the entry of contamination into the water supply during any activity.
Compliance period: 1 year
Supplies that use continuous monitoring to demonstrate compliance need to follow continuous monitoring rules G12, G13, G15, G16, and G17.
Rule G12 – continuous monitoring equipment (assurance rule)
Continuous on-line monitoring equipment used to demonstrate compliance with any rule must:
(a) be calibrated in accordance with the instrument manufacturer’s specified procedures and frequency; and
(b) have calibration verified in accordance with the instrument manufacturer’s specified procedures.
Compliance period: 1 year
Rule G13 – continuous monitoring equipment (assurance rule)
For continuous monitoring equipment that is used to demonstrate compliance against treatment Rules (T1, T2, T3), the separation between data records must be no more than 1 minute.
Compliance period: 1 year
Rule G15 – continuous monitoring equipment (assurance rule)
For continuous monitoring equipment that is used to assess source water or to demonstrate compliance against distribution zone Rules, the separation between data records must be no more than 30 minutes.
Compliance period: 1 year
Rule G16 – continuous monitoring equipment (assurance rule)
Continuous monitoring equipment used to monitor FAC in distribution zones must be appropriately pH and temperature compensated.
Compliance period: 1 year
Rule G17 – continuous monitoring equipment (monitoring rule)
Where continuous monitoring equipment that is used to demonstrate compliance (excludes source water monitoring) fails, or is not otherwise able to provide data, grab samples can be taken to substitute for continuous data if analyses of the parameters is undertaken for at least every 30-minute period that the continuous monitoring equipment is not operating.
Compliance period: Dependent on the parameter and circumstances.
Source Water Rules
The following S1 Source Water Rules apply.
Rule S1.1 - surface water and groundwater source monitoring (monitoring rule)
Surface and groundwater sources must be monitored:
(a) at least every 3 months for the following:
(i) E. coli
(ii) total coliforms; and
(b) at least every 3 years for the following:
(i) pH
(ii) turbidity
(iii) iron
(iv) manganese
(v) nitrate
(vi) arsenic
(vii) boron.
Rule S1.2 - roof source water monitoring (monitoring rule)
Roof water sources must be monitored:
(a) at least every 3 months for the following:
(i) E. coli
(ii) total coliforms; and
(b) at least every 3 years for the following:
(i) cadmium
(ii) copper
(iii) lead.
Rule S1.3 - chemical determinands (monitoring rule)
Any chemical determinands that are identified as presenting a risk to the supply or are found to exceed 50% of their MAV in source water samples must be monitored at least annually until 3 consecutive results from source water samples are less than the 50% of the MAV.
Compliance period: 1 year
Rule S1.4- collection points (non-reporting rule)
Samples collected under:
(a) rule S1.1 must be collected at the abstraction point or treatment plant prior to treatment and/or mixing with other sources; and
(b) rule S1.2 must be collected at the raw water storage tank outlet and prior to any treatment.
Rule S1.5 - cyanobacteria risk (non-reporting rule)
The following measures must be taken in relation to surface water intakes:
(a) Each month between October and May (inclusive):
(i) the water and area around and upstream of the intake must be inspected for the presence of benthic cyanobacteria mats and planktonic cyanobacterial growth; or
(ii) water must be monitored for cyanobacterial cell count at the treatment plant prior to mixing and treatment.
(b) If there is evidence of cyanobacterial growth, steps must be taken to evaluate the cyanotoxin risk to consumers.
(c) If there is a risk of supplying water with cyanotoxins that exceed MAVs, abstraction of water must be discontinued, an alternative source used, or treatment installed, until the risk is no longer present.
Rule S1.6 - taste or odour complaints (non-reporting rule)
Consumer taste or odour complaints, which have the potential to relate to cyanobacteria, must be:
(a) recorded; and
(b) investigated to determine the cause.
Treatment Rules
The following T1 Treatment Rules apply.
Rule T1.1 - monitoring requirements (monitoring rule)
Water leaving a treatment plant must be monitored at least every 3 months for the following:
(a) E. coli
(b) total coliforms
(c) turbidity
Compliance period: 1 month
Rule T1.2 - monitoring requirements (monitoring rule)
Any additional determinand(s) which are identified as presenting a risk to the supply must be monitored at least every 3 months in water leaving a treatment plant until 3 consecutive results from treated water samples confirm the determinand(s) to be less than 50% of the MAV.
Compliance period: 1 year
Rule T1.3 - water filtering (non-reporting rule)
All water, excluding groundwater abstracted from a depth of greater than 30 metres, must be filtered by a:
(a) cartridge filter system that includes a 5 micron (nominal) or smaller pore size; or
(b) back-washable media filter; or
(c) slow sand (biological) filter; or
(d) membrane filter.
Rule T1.4 - water filtering (non-reporting rule)
Where filtration is used:
(a) the filtration system must be operated within the manufacturer’s design specifications at all times; and
(b) pumps must not be connected directly to the discharge side of any cartridge filter; and
(c) where pumping occurs after filtration, the filtrate must first pass directly to a tank.
Rule T1.5 - UV disinfection (non-reporting rule)
All water passing through a treatment plant must be disinfected with UV light and UV units must:
(a) deliver at least 40 mJ/cm2 (or equivalent) reduction equivalent dose (RED) of UV light; and
(b) be installed, maintained and operated according to the manufacturer’s instructions; and
(c) be certified to (and operate within the specifications of) at least one of the following standards unless purchased before 1 August 2022:
(i) NSF/ANSI 55 Class A (NSF, ANSI n.d):
(ii) Ultraviolet Disinfection Guidance Manual (USEPA 2006b):
(iii) DVGW Technical Standard W294 (DVGW 2006):
(iv) ÖNORM M 5873-1: 2020 01 01; or ÖNORM M5873 (Osterreichisches Normungsinstitut 2001):
(v) DIN 19294-1:2020-08.
What if my population varies?
The rules described above apply to a normal consumer population of 26 to 100 people on your drinking water network. However, it’s possible that your population might temporarily increase at times during the year (for example, during holiday periods).
If such periods do not exceed 60 days (in total) during any 12-month period, you can continue to follow the rules for small self-supplied buildings supplies, but you’ll need to follow additional rules during the period(s) of increased population. The additional rules are detailed below.
If your population exceeds 100 people for more than 60 days during any 12-month period, you’ll need to follow the rules for a medium self-supplied buildings supply (up to and including 500 people) or a large self-supplied buildings supply (over 500 people).
Varying population rule VP1 – population temporarily exceeds 100 people (non-reporting rule)
If a supply operating under level 1 treatment or distribution rules exceeds 100 people, the following additional monitoring requirements must be met in the week before the population exceeds 100 people (if predictable) and continuing every week until the population reduces below 100 people:
(a) water leaving a treatment plant must be monitored at least weekly for the following:
(i) E. coli
(ii) total coliforms
(b) if the supply has distribution zones, water from each distribution zone must be monitored at least weekly for the following:
(i) E. coli
(ii) total coliforms.
Varying population rule VP2 – population temporarily exceeds 500 people (non-reporting rule)
If a supply operating under level 1 treatment or level 1 distribution rules exceeds 500 people, the following additional monitoring requirements must be met from 1 week prior before the population exceeds 500 people (if predictable) and continuing every week until the population reduces to below 500 people:
(a) water leaving a treatment plant must be monitored at least twice weekly for the following:
(i) E. coli
(ii) total coliforms
(b) if the supply has distribution zones, water from each distribution zone must be monitored at least twice weekly for the following
(i) E. coli
(ii) total coliforms
(c) monitoring must continue in accordance with VP.1 where the population reduces below 500 people and remains above 100 people for any period of time.
Acceptable Solution
You might choose to use an Acceptable Solution to ensure safe drinking water is provided to your community and show compliance with the Water Services Act 2021outbound.
An Acceptable Solution is a readymade method of demonstrating legal compliance with particular sections of the Act. If you use the Acceptable Solution described below you won't need to prepare a drinking water safety plan or follow the Drinking Water Quality Assurance Rules above.
The Acceptable Solution for self-supplied buildings uses a centralised treatment system to make water safe to drink. A centralised treatment system treats source water at a plant or central point before the water is piped to another building or buildings. The centralised treatment system under this Acceptable Solution is made up of cartridge filters to remove dirt and other suspended particles from the water and a UV disinfection system to control microorganisms such as bacteria and viruses.
The Acceptable Solution for self-supplied buildings can be used to supply:
- a single building with a base population of no more than 500 people
- up to three buildings with a total base population of no more than 100 people
- up to 10 buildings with a total base population of no more than 500 people, as long as the pipes that convey treated water between buildings are not laid through or within 50 metres of:
- a sewage disposal field or effluent discharge (e.g. a septic tank or other wastewater treatment system)
- an underground storage tank (such as a petrol station fuel tank)
- a waste pond
- a landfill
- an offal pit
- areas where pesticides or animal effluent is applied to land
- other contaminated sites.
View the full Acceptable Solution here. The key requirements are summarised below.
Choosing between the Acceptable Solution and the Rules
If you choose to use an Acceptable Solution, you:
|
Do need to |
Don’t need to |
|
|
There are factors that drinking water suppliers can consider to help them choose between following an Acceptable Solution or preparing a drinking water safety plan and following the Rules. These factors include:
- the cost of a centralised treatment system
- the stability of your population – is it likely to increase above the thresholds for an Acceptable Solution noted in the table above?
- the practicality of installing the treatment system
- the availability of qualified, trained or experienced people to install, operate and maintain the treatment system
- the availability of people to meet the greater reporting requirements of the Rules
- the suitability of your source water (see below).
Use qualified, trained or experienced people
It's important that the people who install and maintain your treatment system, monitor your source water and manage your operations are suitably qualified, trained or experienced. Different tasks will require different skills and experience.
Installing systems
A registered plumber must be used to install treatment systems if sanitary plumbing work is involved. The systems must be installed in accordance with the manufacturer's instructions.
Monitoring water
The monitoring of source water, particularly in supplies at risk from cyanobacteria, is a very important role (see ‘Suitable source water is critical’ below).
No specific qualifications currently apply to this role. However, availability and local knowledge are fundamentally important. We suggest that you consider making this a shared role, especially at times when the risk of flooding or cyanobacteria blooms is higher.
The people monitoring the quality of your source water should take a cautious approach and be willing to call on expert advice when they are unsure.
Managing operations
The equipment used to operate a water scheme can vary in complexity, so the person or people who operate your scheme should have a corresponding level of experience and knowledge. Operators should be willing to seek expert assistance when required and ensure they gain the required training.
Suitable source water is critical
Groundwater from a bore or spring or surface water from rivers, lakes, streams or open irrigation channels can be used as source water under the small-medium self-supplied buildings Acceptable Solution.
Good treatment starts with good source water. If the quality of the water coming into the treatment system is low, the system may not work properly and it may not be possible to make the water safe to drink.
Generally, groundwater is better suited to treatment with cartridge filters and UV light than surface water. Surface water sources are at much greater risk of experiencing problems that can reduce the effectiveness of the treatment and place the health of consumers at risk.
Factors affecting the quality of source water:
- Turbidity – the haziness or cloudiness of water – is caused by the presence of fine suspended particles such as soil and organic matter. If turbidity is high, it can affect UV transmittance and reduce the effectiveness of UV treatment. High turbidity can also reduce the effectiveness of disinfectants such as chlorine and cause filters to block.
- The turbidity in your source water must be low enough to ensure filters will last at least a month before needing replacement.
- UV transmittance must be high enough that the UV dose reaches pathogens that may be in the water.
- High quantities of manganese and iron in the water can also interfere with UV treatment systems by coating the UV sleeve.
- Chemicals such as nitrate and arsenic in the water cannot be removed and if present in high enough concentrations can endanger the health of consumers. Chemical levels in your source water must not exceed the Maximum Acceptable Values (MAVs) shown in the Drinking Water Standardsoutbound.
You’ll need to monitor all these factors to determine whether the source water is suitable for the small-medium self-supplied buildings Acceptable Solution or whether following the Rules is the better option.
You’ll also need to monitor regularly once the Acceptable Solution is in place (see ‘Monitoring the water in your network’ below). All chemical and microbiological monitoring must be undertaken by an accredited laboratory according to the lab’s instructions.
Cyanobacteria risk in surface water sources
Microscopic organisms called cyanobacteria are commonly found in surface water and can present a significant risk to drinking water. Cyanobacteria themselves are not dangerous to health. However, under some circumstances, some cyanobacteria can release cyanotoxins that can be very harmful to human and animal health.
Cyanobacteria are often referred to as ‘blue-green algae’ and may form colonies referred to as ‘algal blooms’.
If you’re sourcing your water from a lake, river or other surface water source, you must inspect the water and surrounding area each month (from October to May) for signs of cyanobacterial growth (like mats or blooms). If you see any signs, you’ll need to assess whether there’s a toxin risk and, if so, develop and follow a response plan.
If you or anyone else drinking from your supply is concerned about the taste or odour of the water (particularly an earthy or musty smell or taste), which may relate to cyanobacteria, you must investigate it.
Protection for springs or bores
Where water is sourced from a spring or bore, the following requirements must be met under the small-medium self-supplied buildings Acceptable Solution:
- Springs and bores must be protected by headworks that minimise the risk of contamination from nearby surface water.
- Farm animals must be excluded from an area extending at least five metres in all directions from the headworks of a bore, spring or spring-fed pond.
- In addition, springs and bores must not be affected by contamination from any of the following:
- A sewage disposal field or effluent discharge (for example, a septic tank or other wastewater treatment system).
- An underground storage tank (such as those used at a petrol station).
- A waste pond.
- A landfill.
- An offal pit.
- Areas where pesticides or animal effluent are applied to land.
- Aquifers contaminated with, or at risk of contamination with, sewage from exfiltration and/or pump station overflows.
- Other contaminated sites.
Springs and bores that provide geothermal water cannot be used as source water under this Acceptable Solution. If you’re sourcing water from a spring or bore you should also familiarise yourself with any relevant requirements that your regional council has.
Roof water
Water collected from a roof can pick up contaminants. If you’re using roof water as a source there are special restrictions and monitoring requirements that apply. See ‘Monitoring untreated source water’ below.
Pre-treatment of water
Pre-treatment of source water before it enters the end-point treatment system may be needed for some source waters but is not compulsory for all sources. Pre-treatment might include reduction of turbidity or the addition of chlorine to control microorganisms.
While pre-treatment is not required to meet the water quality requirements of this Acceptable Solution, it may be necessary to provide consistently suitable water – particularly in schemes using surface water that might be subject to high turbidity.
Requirements of the central treatment system
Your central treatment system must consist of a cartridge filtration system and a ultraviolet (UV) disinfection system.
- At least one cartridge filter must have a 5 micron or less nominal pore size.
- The ultraviolet (UV) disinfection system must deliver a minimum reduction equivalent dose of 40 mJ/cm2.
In addition, the central treatment system must be installed to meet the instantaneous peak demand for treated drinking water and in accordance with the manufacturer’s instructions and requirements.
When considering purchase of an end-point treatment unit, we recommend using a reputable end-point treatment equipment supplier to ensure the 5 micron and 40 mJ requirements are met.
Validated and unvalidated UV treatment systems
Before the changes introduced by the Water Service Authority – Taumata Arowai in 2025, only UV treatment systems that had been validated or certified to one of four international standards (referred to as ‘validated’ units) could be used under an Acceptable Solution. Validation requires that a unit provides some form of alarm or notification to consumers if UV treatment is ineffective.
However, this requirement increased the complexity and cost of treatment systems and was consequently reviewed.
Under the Acceptable Solution for self-supplied buildings introduced in 2025, validated systems are still required if:
- the base population exceeds 25 people, or
- the treatment system is supplying drinking water to the public (for example, at cafés, marae, schools, community halls and campgrounds). Note that population limits (see above) still apply.
Unvalidated systems can be used at consumer properties with fewer than 25 people that do not serve a community purpose or the public (for example, a small workplace such as a farm building with under 25 staff).
Unvalidated units still have to meet the basic requirements including written confirmation the system can deliver at least 40 mJ/cm2 reduction equivalent dose of UV light.
Premises such as schools, community halls, sports clubs, cafes and campgrounds must use a validated unit no matter what their base population is.
Using storage tanks
Storing water in tanks poses risks, especially from contamination by animals or their droppings. With proper care, these risks can be significantly reduced.
Tanks used to store treated water under this Acceptable Solution must be inspected every three months to ensure:
- they are secured against rainwater and surface water getting in
- inlets, lids, overflows and any other small gaps are secure from contamination by vermin, birds, animals, faecal material, or other material.
Tanks used to store untreated drinking water should be inspected annually for the same issues.
Untreated water from any other source should first be delivered into an untreated water storage tank so that all water to be used for drinking passes through the treatment system.
Monitoring untreated source water
Bore, spring or surface water
You’re required to monitor your untreated bore, spring or surface source water at least every 3 months for:
- microbiological content: E. coli, total coliforms
- physical properties: turbidity, UV transmittance.
You’re also required to monitor at least once a year for:
- chemical content: iron, manganese, nitrate, arsenic, boron, hardness and any other chemicals that are identified as presenting a risk to the supply.
All chemical and microbiological monitoring must be undertaken by an accredited laboratory, according to the lab’s instructions. Physical monitoring is generally done by hand-held on-site measuring devices.
Roof water
Water collected from a roof can pick up contaminants, so if you’re using roof water as a source for your drinking water supply you need to ensure that any materials the water comes into contact with (for example, roof cladding, spouting, fittings and tanks) don’t leach chemicals or other substances that will make the water unsafe to drink even after treatment.
Regardless of the materials used, before you adopt this Acceptable Solution using roof water as a source (and then every 3 years following) a sample of untreated water from the roof must be tested for the following chemicals:
- Cadmium (found in some types of roof paint).
- Copper (often sourced from unpainted, treated wood shingles or copper spouting).
- Lead.
The untreated roof water must also be tested every 3 months for the following microbiological components:
In addition, as far as practicable, you should keep roof surfaces used for the collection of drinking water free from decaying debris, leaves, branches, birds’ nests and bird or animal droppings. Your water storage and treatment system must be able to be disconnected from the roof during cleaning and maintenance.
Monitoring water after treatment
There is risk under this Acceptable Solution that, when water is treated in one building then supplied to others, that contaminants could enter the water through, for example, cracked pipes or loose joints.
These risks must be managed by monitoring water taken from a tap in a building that is the greatest distance from the building where the treatment system is located.
As a provider of a small self-supplied buildings supply (serving a base population of 100 or fewer people), you’re required to monitor every 3 months for:
All monitoring must be undertaken by an accredited laboratory, according to the lab’s instructions. Learn more about monitoring your source water.
If your population temporarily increases above 100 (for example, during a gathering or event), additional samples of treated water must be collected and tested:
- in the week before the population increases (if the increase is predictable); and
- weekly until the population reduces to 100 or fewer.
If your population increases above 500 (for example, for a gathering event) additional samples of treated water must be collected and tested:
- in the week before the population increases if the increase is predictable; and
- twice weekly until the population reduces below 500.
The greater the population being supplied under this Acceptable Solution, the more vigilant the supplier needs to be in relation to contamination of the treated water. This is why the testing requirements increase alongside the population.
If testing reveals a problem
If any of the tests show that levels of chemical or microbiological contaminants are above the maximum acceptable values (MAVs) shown in the Drinking Water Standardsoutbound, the testing laboratory will advise the Water Services Authority – Taumata Arowai.
You are also required to notify the Authority when such exceedances occur.
The laboratory will also advise you. You must then take all practicable steps to let affected consumers know that the drinking water is or may be unsafe and what measures are being taken to provide an alternate supply while the cause of the problem is identified and rectified.
If a microbiological test result exceeds the MAV you may need to issue a boil water advisory while the cause of the exceedance is identified and fixed. Boiling water correctly will kill microbiological contaminants (but have no effect on chemical MAV exceedances).
Record-keeping
You’re required to keep records of information and communications relating to:
- installation, maintenance and testing of treatment systems
- monitoring results
- all communication with property owners and consumers
- your emergency plans (see below) and any responses you’ve made.
These records must be kept for at least three years.
Preparing for an emergency
Think ahead about anything that could stop your treatment systems from working or prevent you from supplying enough drinking water for your community.
These could be natural events such as earthquakes and floods or manmade situations such as a power outage or chemical spill.
Suppliers must have a response plan for each of those situations and must follow it if an event happens.
Transitioning from an earlier Acceptable Solution
If you were meeting the requirements of an earlier Acceptable Solution (for spring and bore water or roof water sources), you have one year from 4 September 2025 (the date the new Acceptable Solutions were enacted) to start complying with this new Acceptable Solution for small-medium self-supplied buildings.
You can choose to switch over to the new requirements earlier.
Exemptions
For some drinking water suppliers, it might be unreasonable or impractical to comply with the Act and suppliers can apply for an exemption from some requirements.
When seeking an exemption, you’ll need to tell us how the exemption will be consistent with the main purpose of the Act – ensuring that drinking water suppliers provide safe drinking water to consumers. You’ll also need to tell us how you would manage risks affecting your drinking water supply.
Head to the exemptions page for information on types of exemptions and how to apply.
This webpage is intended as a guideline and summarises legal requirements but does not address every requirement under the Water Services Act. It is not intended to be definitive and is not legal advice. Drinking water suppliers are responsible for understanding and complying with their legislative duties. The Authority may review and revise this page over time. If you are using a printed copy, please check the website to make sure it is up to date.