Ngā waehanga o ngā kura wai marangai me ngā mahi whakapaipai Rainwater tank components and maintenance

Find out what you need to set up your rainwater tank to ensure the water is safe and healthy.

For a basic rainwater tank set up, you will need:

• Rainwater tank: Should be long-lasting, watertight with an opaque exterior, and a tight cover to prevent evaporation and to keep out insects, birds and rodents.
• Overflow outlet: Ensures excess water flows back into your existing onsite stormwater discharge point.

You may also find the following useful:

• Gutter screen and leaf guards: Installed at the top of downpipes to prevent leaves and debris from entering the tank.
• First flush diverter: The first rainfall usually carries most of the contaminants from your roof (dirt, debris and bird droppings). This device diverts the 'dirty' water away.
• Filters: These include simple cartridges, fine mesh and UV filtration systems that can remove sediment, harmful microbes and alter the pH balance of your water. All filters require maintenance and replacement.
• Chlorination: Consider adding chlorine tablets to improve the quality of your water and prevent algae from forming. 
• Pump: While gravity-fed systems are an option, most households with a tank on the ground will require a pump to improve water pressure. A pump requires a power supply. Use a registered electrician to ensure a safe installation.

You can collect rainwater from most roof types including pressed metal and clay tiles. Your roof, flashings and gutters must not contain lead or lead paint. This can dissolve and contaminate your water supply.

Gutters and downpipes should be properly sized and sloped to maximise rainwater collection.

If you are using water from a rainwater collection tank, you must ensure the quality of it is safe and fit for its intended use.

You can lessen health risks by:

• using a registered plumber to install your tank
• ensuring your roof and gutters are clean
• using filters, mesh guards and a backflow prevention device
• clearly labelling rainwater tanks to indicate the water is not for drinking.

Non-potable (non-drinkable) rainwater tank water should not be consumed unless there is a need for emergency supply. In this case, we recommend following Ministry of Health's HealthEd website guidelines.

If you plan to use the water indoors, you will need a qualified, registered plumber to safely connect the rainwater tank to the internal plumbing of your property.

This is to ensure the protection of the public water supply through backflow prevention, as well as the quality of water supplied by the tank. Find out more about backflow prevention on the Watercare website.

Installation cost

A tank can cost from $200 for a basic rain barrel to around $3000 for a 3000-5000-litre tank, depending on the design and what it is made of. Consenting and installation costs are additional considerations.

Watercare charge each household a fee for collecting and treating their wastewater. This fee covers your contribution to maintaining the wastewater network.
You may need to get a water meter for your rainwater tank if you would like to:

• use a rainwater tank for 100 per cent of your water needs
• connect to the wastewater reticulated system.

Learn about what you will need to set up a rainwater system in your backyard.

View our rainwater tank video collection on YouTube.

Read the full transcripts for these videos.

It is important to maintain a rainwater tank regularly to ensure it is operating as intended and that there are no water quality issues.

Maintenance includes cleaning pre-screening devices, filters, gutters and clearing any overhanging vegetation around your roof area. Periodic maintenance of the tank and pipework as well as internal inspections are also required.

Discuss specific maintenance requirements with your tank supplier and/or a registered plumber.

It is recommended you keep a copy of your operation and maintenance manual on site and provide a copy to us for safe record keeping.

Further information

For more information on rainwater tank maintenance, see the operation and maintenance manual that came with your tank, or read our guidance document for on-site stormwater tanks.

​For information on maintaining the quality of your rainwater, visit the Ministry of Health's website on Water collection tanks and safe household water and download its drinking water publications.