Acceptable Solutions
Some drinking water suppliers can follow an Acceptable Solution instead of the Drinking Water Quality Assurance Rules to ensure the water they supply is safe to drink.
Every day, drinking water suppliers play a vital role supporting the health and wellbeing of people across New Zealand by providing them with safe, reliable drinking water.
To help, we provide different compliance pathways that suppliers can follow to meet their responsibilities. In general, the simpler (or lower risk) the supply, the simpler the requirements.
An Acceptable Solution is one possible compliance pathway for some:
- rural supplies that provide water for farm use (e.g. irrigation, stock) as well as for people to drink
- drinking water supplies that serve 500 people or fewer.
For some suppliers, following the requirements of an Acceptable Solution may be a more straightforward and cost-effective way to meet their responsibilities than completing a drinking water safety plan and following the Drinking Water Quality Assurance Rules (the Rules).
Acceptable Solutions enable water to be treated at or near any buildings where people will drink it. This could include using an end-point treatment system, which uses cartridge filters and ultraviolet (UV) light to disinfect the water.
Updated Acceptable Solutions
In September 2025, we updated the Acceptable Solutions to make them easier to understand and follow. Our aim was to save suppliers and their communities time, effort and cost while providing good quality water to the people who drink it every day.
Rather than a mix of supply types and water sources, Acceptable Solutions are now available for three different types of supplies. This will make it easier to figure out if an Acceptable Solution is right for your supply and community.
Each Acceptable Solution is a legal document that sets requirements. This goes hand in hand with guidance to help you understand what you need to do to meet those requirements.
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Acceptable Solution |
Supply attributes |
Key information |
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Mixed-use Rural |
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Small to Medium Networks |
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Self-supplied Buildings |
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To make key aspects of Acceptable Solutions easier to understand, we’ll keep improving and adding to the guidance over time.
Find out more
- Join us at an online information session to learn more about what’s changed.
- Read questions and answers to find out more about what’s changed.
- Would you like to know what people told us during consultation?
Clarifying responsibilities
A few suppliers have asked us who holds specific responsibilities under an Acceptable Solution. In February 2025, we published a policy statement and flowchart to help clarify this.
Choosing between an Acceptable Solution and the Rules
If you choose to use an Acceptable Solution, you:
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Do need to |
Don’t need to |
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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 multiple end-point treatment systems versus a single 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 end-point treatment systems
- the availability of suitably qualified and experienced people to install, operate and maintain the chosen treatment system
- the availability of people to meet the greater reporting requirements of the Rules.
If an Acceptable Solution is available to your type of drinking water supply, you can see guidance for the Acceptable Solution alongside the Rules that apply to you by visiting your supply-type landing page:
- Mixed-use rural supply
- Small networked supply
- Medium networked supply
- Small self-supplied buildings supply
- Medium self-supplied buildings supply
Seeing the Acceptable Solutions guidance and the Rules together in one place might make it easier for you to choose between the two.
If you’re not sure what type of supply you provide, you can find out here.
Understanding your source water is key
The quality and characteristics of source water are critical to determining whether an Acceptable Solution is the best choice for your supply. In general, bore or spring water sources are best for end-point treatment. A roof source, where rainwater is collected from a roof into a storage tank, is also generally suitable if proper safeguards are in place.
Surface water sources (lakes, rivers or streams) are more challenging. Surface water sources are at much greater risk of experiencing the following problems, which can reduce the effectiveness of end-point treatment and put public health at risk.
- 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.
- High quantities of manganese and iron in the water can also interfere with UV treatment systems.
- Chemicals such as nitrate and arsenic in the water cannot be removed and if present in high enough concentrations can put public health at risk.
- 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 toxins called cyanotoxins that can be very harmful to human and animal health.
Before adopting an Acceptable Solution, a supplier is required to monitor the proposed drinking water source for each of these issues.
An accredited testing laboratory must be used to analyse particular source water samples. Turbidity and UV transmittance can either be tested at a laboratory or using a portable instrument. Turbidity is best measured by a portable instrument because the particles can settle while the sample is left standing around.
The supplier will also need to prepare a response plan in the event that problems arise that could put public health at risk.
These factors might influence the supplier’s decision on whether to adopt an Acceptable Solution.
Overview of the requirements of each Acceptable Solution
Acceptable Solution for mixed-use rural supplies
General
- A registered plumber must be used to install the end-point treatment system if the work involves sanitary plumbing.
- Trained, qualified and/or suitably experienced or supervised people need to be available to operate and maintain any aspect of the drinking water supply.
- It is recommended that the end-point treatment system is purchased from a reputable New Zealand-based supplier.
Source water
- Source water must be suitable with respect to the levels of turbidity, UV transmittance and concentrations of iron, manganese and other chemicals.
- If a surface water source is used, the cyanobacteria risk must be assessed and managed. A cyanobacteria response plan is required so you know what to do if the risk elevates.
- If spring or bore source water is used, it must be:
- protected by headworks that minimise contamination by surface water
- protected from farm animals
- protected from contamination by a sewage disposal field or discharge, underground storage tank (e.g. fuel), waste pond, landfill, offal pit, areas where pesticides or animal effluent are applied to the land, and other contaminated areas.
- Source water can be supplemented with another supply (e.g. from a roof) provided it feeds into the end-point treatment system before consumption.
- 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.
End-point treatment system(s)
- End-point treatment systems must be installed at every property connected to the supply where the water is used for drinking. The systems must be installed by a registered plumber and in accordance with the manufacturer's instructions.
- The system must be installed so it can meet instantaneous peak demand.
- The system must include at least one cartridge filter with a pore size of 5 microns or less.
- The system must include a UV treatment system that delivers a minimum reduction equivalent dose of 40 mJ/cm2.
- The flow of water through the UV treatment system must be restricted or monitored so it does not exceed the manufacturer's recommended flow rate.
- A validated UV treatment system must be used if 25 or more people are served by a treatment system, or water is being supplied to a community or the public (e.g. a school, marae, café, sports club or camping ground).
- An unvalidated UV treatment system is acceptable if fewer than 25 people are served by a treatment system and it is not serving a community or the public (e.g. a small workplace such as a farm building with under 25 staff).
Backflow prevention
- A backflow prevention system comprising either an air gap or a backflow prevention device (either non-testable dual check valves, non-testable double check valves or testable devices) must be installed at every connection to the supply.
Storage tanks
- It’s good practice to protect tanks used to store drinking water from safety risks including animal faeces.
- Suppliers are required to remind the people they supply, at least annually, of the need to:
- secure tanks against rainwater (note – rainwater can be used to supplement the supply, but it should pass through the treatment system before being stored in tanks)
- secure tanks against contamination by vermin, birds, animal faeces and other contaminants
- Tanks should be inspected regularly for signs of contamination.
Supply restrictions
- An end-point treatment system serving one building must not serve more than 500 people.
- An end-point treatment system serving up to three buildings on one property (or adjoining properties with common ownership) must not serve a base population of more than 100 people.
- If the number of people you supply varies during the year, these restrictions can be exceeded for up to 60 days within any 12-month period – provided the treatment system has the capacity to cope.
Emergency response
- Suppliers are required to plan for events such as earthquakes or weather events that could stop the end-point treatment system from working or prevent the supply of sufficient drinking water.
- Suppliers are required to prepare a written emergency response plan.
Monitoring, reporting and record-keeping
- Before the Acceptable Solution is adopted, and then at least every three months, the source water must be monitored for:
- microbiological content – E. coli and total coliforms
- physical properties – turbidity and UV transmittance.
- At least once a year, the source water must be monitored for:
- Monitoring must be undertaken by an accredited laboratory (apart from monitoring of turbidity and UV transmittance, which can either be tested at a laboratory or using a portable instrument).
- Suppliers must inform the people they supply, and any other suppliers connected to the supply, of the results of monitoring.
- A written record of installation, maintenance and testing of end-point treatment systems and supply components (e.g. tanks, pipes and pumps) must be kept for at least three years.
- A record of all communications with the people supplied and others connected to the supply must be kept for at least three years.
- A written emergency response plan must be maintained.
Transitioning from an earlier Acceptable Solution
- Suppliers meeting the requirements of an earlier Acceptable Solution (for spring and bore water or roof water sources) have one year from 4 September 2025 (the date the updated Acceptable Solution came into effect) to start complying with this new Acceptable Solution.
- Suppliers can switch to the new requirements earlier if desired.
Acceptable Solution for small to medium networked supplies
General
- A registered plumber must be used to install the end-point treatment system if the work involves sanitary plumbing.
- Trained, qualified and/or suitably experienced or supervised people need to be available to operate and maintain any aspect of the drinking water supply.
- It is recommended that the end-point treatment system is purchased from a reputable New Zealand-based supplier.
Source water
- Source water must be suitable with respect to the levels of turbidity, UV transmittance and concentrations of iron, manganese and other chemicals.
- If a surface water source is used, the cyanobacteria risk must be assessed and managed. A cyanobacteria response plan is required in the event that the risk elevates.
- If spring or bore source water is used, it must be:
- protected by headworks that minimise contamination by surface water
- protected from farm animals
- protected from contamination by a sewage disposal field or discharge, underground storage tank (e.g. fuel), waste pond, landfill, offal pit, areas where pesticides or animal effluent are applied to the land, and other contaminated areas.
- Source water can be supplemented with another supply (e.g. from a roof) provided it feeds into the end-point treatment system before consumption.
- 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.
End-point treatment system(s)
- End-point treatment systems must be installed at every property connected to the supply where the water is used for drinking. The systems must be installed by a registered plumber and in accordance with the manufacturer's instructions.
- The system must be installed so it can meet instantaneous peak demand.
- The system must include at least one cartridge filter with a pore size of 5 microns or less.
- The system must include a UV treatment system that delivers a minimum reduction equivalent dose of 40 mJ/cm2.
- The flow of water through the UV treatment system must be restricted or monitored so it does not exceed the manufacturer's recommended flow rate.
- A validated UV treatment system must be used if 25 or more people are served by a treatment system, or water is being supplied to a community or the public (e.g. a school, marae, café, sports club or camping ground).
- An unvalidated UV treatment system is acceptable if fewer than 25 people are served by a treatment system and it is not serving a community or the public (e.g. a small workplace such as a farm building with under 25 staff).
Backflow prevention
- A backflow prevention system comprising either an air gap or a backflow prevention device (either non-testable dual check valves, non-testable double check valves or testable devices) must be installed at every connection to the supply.
Storage tanks
- It's good practice to protect tanks used to store drinking water from safety risks including animal faeces.
- Suppliers are required to remind the people they supply of the need, at least annually, to:
- secure tanks against rainwater
- secure tanks against contamination by vermin, birds, animal faeces and other contaminants
- Tanks should be inspected regularly for signs of contamination.
Supply restrictions
- An end-point treatment system serving one building must not serve more than 500 people.
- An end-point treatment system serving up to three buildings on one property (or adjoining properties with common ownership) must not serve a base population of more than 100 people.
- If populations vary during the year, these restrictions can be exceeded for up to 60 days within any 12-month period – provided the treatment system has the capacity to cope.
Emergency response
- Suppliers are required to plan for events such as earthquakes or weather events that could stop the end-point treatment system from working or prevent the supply of sufficient drinking water.
- Suppliers are required to prepare a written emergency response plan.
Monitoring, reporting and record-keeping
- Before the Acceptable Solution is adopted, and then at least every three months, the source water must be monitored for:
- microbiological content – E. coli and total coliforms
- physical properties – turbidity and UV transmittance.
- At least once a year, the source water must be monitored for:
- If roof water is used as a source, it must also be monitored before adopting this Acceptable Solution, and then every three years following, for:
- Monitoring must be undertaken by an accredited laboratory (apart from monitoring of turbidity and UV transmittance, which can either be tested at a laboratory or using a portable instrument).
- Suppliers must inform the people they supply, and any other suppliers connected to the supply, of the results of monitoring.
- A written record of installation, maintenance and testing of end-point treatment systems and supply components (e.g. tanks, pipes and pumps) must be kept for at least three years.
- A record of information provided to the people they supply and others connected to the supply must be kept for at least three years.
- A written emergency response plan must be maintained.
Transitioning from an earlier Acceptable Solution
- Suppliers meeting the requirements of an earlier Acceptable Solution (for spring and bore water or roof water sources) have one year from 4 September 2025 (the date the updated Acceptable Solution came into effect) to start complying with this new Acceptable Solution.
- Suppliers can switch to the new requirements earlier if desired.
Acceptable Solution for self-supplied buildings
General
- A registered plumber must be used to install the treatment system if the work involves sanitary plumbing.
- Trained, qualified and/or suitably experienced or supervised people need to be available to operate and maintain any aspect of the drinking water supply.
- It is recommended that the treatment system be purchased from a reputable New Zealand-based supplier.
Eligible supplies
- A single building with a base population of no more than 500 people, or
- Up to three buildings with a total base population of no more than 100 people, or
- 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 (e.g. 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.
Source water
- Source water must be suitable with respect to the levels of turbidity, UV transmittance and concentrations of iron, manganese and other chemicals.
- If a surface water source is used, the cyanobacteria risk must be assessed and managed. A cyanobacteria response plan is required in the event that the risk elevates.
- If spring or bore source water is used, it must be:
- protected by headworks that minimise contamination by surface water
- protected from farm animals
- protected from contamination by a sewage disposal field or discharge, underground storage tank (e.g. fuel), waste pond, landfill, offal pit, areas where pesticides or animal effluent are applied to the land, and other contaminated areas.
- Special restrictions and monitoring requirements apply (see below) if roof water is used as a source.
- Source water can be supplemented with another supply (e.g. from a roof) provided it feeds into the treatment system before consumption.
- Pre-treatment of source water before it enters the 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.
Central treatment system
- Components of the central treatment system must be installed by a registered plumber in accordance with the manufacturer's instructions.
- The system must be installed so it can meet instantaneous peak demand.
- The system must include at least one cartridge filter with a pore size of 5 microns or less.
- The system must include a UV treatment system that delivers a minimum reduction equivalent dose of 40 mJ/cm2.
- The flow of water through the UV treatment system must be restricted or monitored so it does not exceed the manufacturer's recommended flow rate.
- A validated UV treatment system must be used if 25 or more people are served by a treatment system, or water is being supplied to a community or the public (e.g. a school, marae, café, sports club or camping ground).
- An unvalidated UV treatment system is acceptable if fewer than 25 people are served by to a treatment system and it is not serving a community or the public (e.g. a small workplace such as a farm building with under 25 staff).
Storage tanks
- It's good practice to protect tanks used to store drinking water from safety risks including animal faeces.
- Suppliers are required every 3 months to:
- secure tanks against rainwater
- secure tanks against contamination by vermin, birds, animal faeces and other contaminants.
- Tanks should be inspected regularly for signs of contamination.
Monitoring untreated source water
- Untreated bore, spring, roof or surface source water must be monitored at least every three months for:
- microbiological content: E. coli, total coliforms
- physical properties: turbidity, UV transmittance.
- At least once a year, the untreated source water must be monitored for:
- If roof water is used as a source, it must also be monitored every three years following, for:
- As far as practicable, roof surfaces used for collecting drinking water should be kept free from decaying debris, leaves, birds’ nests and bird or animal droppings.
- The water storage and treatment system must be able to be disconnected from the roof during cleaning and maintenance.
- All monitoring of source water samples must be undertaken by an accredited laboratory.
Monitoring water after treatment
- Monitoring water after treatment is to manage the risk that, when water is treated in one building then supplied to others, contaminants could enter through, e.g. cracked pipes or loose joints.
- Water taken from the building at greatest distance from the treatment system must be monitored every month (if serving more than 100 people) or every three months (if serving 100 or fewer people) for:
- E. coli
- total coliforms.
- All monitoring of source water samples must be undertaken by an accredited laboratory.
Monitoring of treated water during a temporary population increase
- If the population served by the supply temporarily increases (e.g. during a gathering or event), additional samples of treated water must be collected and tested.
- For small suppliers (normally serving 100 or fewer people), additional samples must be tested:
- in the week before the population increases (if the increase is predictable)
- weekly until the population reduces to 100 or fewer.
- For medium suppliers (normally serving from 101 to 500 people), additional samples must be tested:
- in the week before the population increases if the increase is predictable
- twice weekly until the population reduces below 500.
If monitoring reveals a problem
- The accredited testing laboratory will advise the supplier and the Water Services Authority – Taumata Arowai (the Authority) if monitoring reveals that a determinand’s Maximum Acceptable Value (MAV) has been exceeded.
- Under sections 21 and 22 of the Water Services Act 2021, the supplier must also notify the Authority if a MAV has been exceeded.
- The supplier must take all reasonable steps to let affected people know:
- that the water is or may not be safe to drink
- what measures are being taken to provide an alternative supply while the problem is identified and fixed.
- If microbiological tests prove positive, a boil water notice can be applied while the cause of the exceedance is identified and fixed.
Record-keeping
- The supplier is required to keep records for at least three years of information and communications relating to:
- installation, maintenance and testing of treatment systems
- inspection and maintenance of supply components including storage tanks, pipes and pumps:
- monitoring results
- information provided to property owners and the people they supply
- emergency plans (see below) and any responses made.
Preparing for an emergency
- Suppliers are required to prepare a response plan for events such as earthquakes or weather events that could stop the treatment system from working or prevent the supply of sufficient drinking water.
Transitioning from an earlier Acceptable Solution
- Suppliers meeting the requirements of an earlier Acceptable Solution (for spring and bore water or roof water sources) have one year from 4 September 2025 (the date the updated Acceptable Solution came into effect) to start complying with this new Acceptable Solution for self-supplied buildings.
- Suppliers can switch to the new requirements earlier if desired.