Selling a home on tank or bore water? Under the Health Act it’s an offence to sell a house unless it has an adequate supply of potable water. Raw tank or bore water, untreated and unfiltered, is not potable water, even when it looks clear.
The good news: it’s usually simple to sort, and doing it before you list means buyers get straight answers. Here’s what the law says and what to do. For renting and holiday homes too, see our guide to safe water for rural rentals and sales.
What the law says
In plain English, checked October 2026:
- Health Act 1956, section 39. It’s an offence to sell or let a house unless provision has been made, in line with the Building Code, for an adequate supply of potable water. Fines are up to $500.
- What potable means. Water that is safe to drink and meets the Drinking Water Standards (2022). For E. coli, that’s less than 1 in 100 mL.
- Kitchen and bathroom. The Building Code (clause G12) covers water for drinking, cooking, washing dishes and brushing teeth.
- No certificate. There’s no legal “potable water certificate” for selling a house.
- Agents must disclose. Real estate agents must tell buyers about defects they know of, and can’t mislead or hold back information (REA guidance).
- A LIM isn’t a water test. A LIM says whether the house has a drinking water supply and who supplies it. For your own tank or bore, it only shows what the council knows.
What buyers will want to know
The government’s home-buying guide settled.govt.nz tells lifestyle block buyers to check where the water comes from and whether it’s safe to drink. Expect questions like:
- Has the water been tested, and when?
- What treatment is installed, and does it treat the whole house?
- When was the UV last serviced, and are there records?
- What condition are the tank, gutters and pump in?
A written check and recent lab results answer all of these, and stop the water becoming a last-minute problem.
Get it sorted before you list
- Check. Our Warrant of Fitness checks the whole system: roof, gutters, first flush, tank, pump and filters. You get a written report of what we found and anything that needs doing.
- Test. An E. coli test is $99 + GST. For bores, a full chemical, mineral and heavy metal test, checked against the Drinking Water Standards, is $240 + GST, or $279 + GST with E. coli and turbidity. We take the sample free while we’re on site, or you can drop it in to our shop at 2 Mill Lane, Warkworth.
- Treat. Whole-house UV with sediment filters, so every tap is safe, hot and cold. Ultrafiltration also works. Bore water may also need treatment for iron, manganese or hardness, matched to the test.
- Look after it. We service your UV every 12 months: a new lamp and filters, the quartz sleeve taken out and cleaned, and the UV unit and cold water lines sterilised. We remind you when it’s due and keep the records.
Keep the test results and service records. Health guidance for household supplies says good records “will help if you come to sell the property” (Household water supplies, ESR and Ministry of Health, 2021).
Don’t rely on a shock dose before a test. A shock dose only treats the water in the tank at the time, and the next rain washes new contamination in from the roof. The law asks for potable water all the time, and that takes treatment that works continuously, like UV.
Bore, spring or stream water
The same rule applies to any water that isn’t town supply: it has to be potable, and keep being potable. Bore water can carry minerals and metals as well as bacteria, so start with a full test. Our bore water test (chemicals, minerals and heavy metals, checked against the Drinking Water Standards) is $240 + GST, or $279 + GST with E. coli and turbidity. We then match the treatment to the results. See contaminants in drinking water.
Buying a home on tank water?
A LIM won’t tell you whether the water is safe to drink. Ask for test results and service records, and have the system checked and the water tested before you go unconditional. We can do both.
Selling a home on tank water?
Book a water check before you list. We’ll tell you exactly what’s needed.
Selling a house without potable water: FAQs
Is it illegal to sell a house without potable water in NZ?
Yes. Under section 39 of the Health Act 1956 it’s an offence to sell a house unless provision has been made for an adequate supply of potable water. The fine is up to $500. Raw tank or bore water isn’t potable, so it needs treatment.
Do I need a potable water certificate to sell my house?
No, there’s no legal certificate. But it’s an offence to sell without an adequate supply of potable water, and agents must disclose known defects. Our written Warrant of Fitness report and lab test results give buyers the facts.
Does a LIM show whether the water is safe to drink?
No. A LIM says whether the house has a drinking water supply and who supplies it. For your own tank or bore, it only shows what the council knows. It isn’t a water test.
Will shock dosing the tank before a test sort it out?
No. A shock dose only treats the water in the tank at the time, and the next rain brings new contamination in from the roof. The water has to be potable all the time, so you need continuous treatment, like UV.
How much does a water test cost?
An E. coli test is $99 + GST. For bores, a full chemical, mineral and heavy metal test, checked against the Drinking Water Standards, is $240 + GST, or $279 + GST with E. coli and turbidity. We take the sample free while we’re on site, or you can drop it in to our shop at 2 Mill Lane, Warkworth.
Does this apply to bore water?
Yes. Any water that isn’t town supply must be potable, all the time. Bore water needs a full chemical test as well as an E. coli test, and may need treatment for minerals such as iron, manganese or hardness.