Rainwater Tanks

A rainwater tank

Rainwater tanks are a great way to decrease your demand on treated water from mains water, as well as reducing the stormwater run-off which can pollute waterways.

What can tank water be used for?

Tank water can be used for purposes such as flushing toilets, washing clothing, topping up swimming pools, watering the garden or washing your car.

Things to consider when choosing a rainwater tank

  • What will you use the water for? This will affect the size of the tank you select. A minimum 5000 litre tank is recommended when using the rainwater for household activities. Internal as well as external use of rainwater is the best environmental outcome, as it ensures that the water in the tank is used regularly.
  • How big is your roof?Roof area determines how much water you can collect. If rainwater is only able to be collected from part of your roof, you may need to adjust your downpipes or install more than one tank.
  • Do you have enough space for the tank?A traditional round 5000 litre tank will need an area of 1.7 metres in diameter and 2.3 metres in height. Underground tanks are an option, but they can be expensive and you will need a DA. Slimline tanks may be a better option for limited space. They can be installed between the side of the house and the fenceline provided there is a 450mm gap for access.
  • How will you maintain the tank?Dust and debris on the roof of the house can contaminate the water. A flush-first device should be used, and it should be regularly cleaned. Gutters and leaf-screens should also be regularly checked.
  • What about mosquitoes?To prevent mosquitoes from entering the tank, all inlets and outlets to the tank will need to be blocked with insect-proof screens.

Do I need a development application to install a rainwater tank?

Willoughby City Council residents are not required to lodge a development application (DA) when the
following conditions are met:

If tank/s are:

  • above ground with the capacity not exceeding 10 000 litres;
  • located behind the building line or in the rear yard of a property containing a heritage item; and
  • 450mm from each lot boundary where the tank exceeds 1.8 metres in height and setback 10 metres from a lot boundary if located in an E4 - Environmental Living Zone (or scenic protection zone)

For all other cases, phone Council’s planning team on 9777 1000.

When selecting your tank installer, ensure they are reputable and can demonstrate they comply with the
exempt development provisions of State Environmental Planning Policy – Exempt and Complying Development Codes (Part 2) and all other relevant guidelines for the installation of rainwater tanks.

To encourage the installation of rainwater tanks when properties are being redeveloped, Willoughby Council will:

  • Reduce the storage volume required for mandatory on-site (stormwater) detention systems for single residential developments and redevelopments, and will consider a reduction the storage volume for larger developments.
  • Waive all application and processing fees for DAs and construction certificates required for installation of a rainwater tank holding less than 5500 litres of rainwater on sites that are heritage listed or located in conservation areas. This only applies to rainwater tank installations not associated with any other DA conditions.

Further Information

The Sydney Water website has lots of useful information about types of rainwater tanks, plumbing requirements and advice on maintaining your tank.

NSW Health offers guidelines for maintaining your rainwater tank.