Protecting your Water Tank from Mosquitoes

Published on 18 March 2026

Rainwater tanks are widely used across Queensland, but if they are not properly maintained, they can present a risk to public health. Rainwater tanks can provide ideal conditions for mosquitoes to breed.

Taking simple maintenance steps can help protect your household and the wider community from mosquito-related health risks. Below are important steps to ensure your rainwater tank does not become a health risk to you, your family, or your community.

Maintaining your rainwater tank is an important responsibility to ensure good water quality and to prevent mosquitoes from breeding. Regular inspection and maintenance can significantly reduce health risks to your household and the community.

Rainwater tanks may become a major mosquito breeding site when they are no longer required or when they fall into disrepair. Disused tanks may also harbour rats and mice. Tanks that are no longer required should be drained, cut up and removed to an approved waste disposal site.

How to prevent mosquitoes breeding in your water tank:

1. Ensure all inlets, outlets, and pipes are fitted with mesh screening with openings of approximately 1 mm to prevent mosquitoes entering the tank.
2. Regularly inspect mesh screens and replace them immediately if damaged.
3. Older tanks may not have mosquito-proof mesh installed. Check all pipes and inlets and install mesh screening where required.
4. Check tanks, guttering, and pipework for cracks, rust, or gaps, and seal or repair as needed.
5. Trapped dirt, debris, and moss can become mosquito breeding sites. Inspect inlets and outlets and remove visible material.
6. Rainwater tank overflow outlets can also provide breeding sites. Ensure overflow water drains effectively away from the tank, either into the ground or a stormwater drain.
7. Consider mosquito prevention when installing, maintaining, or modifying rainwater tanks, particularly in relation to overflow design.

Suggested Maintenance Schedule:

Every 3 Months:

• Check and clean the first flush device.

  Every 6 Months:

• Inspect the tank structure, mosquito-proof screens, and flap valves for rips, holes, or defects and repair immediately.
• Check roof gutters for accumulated debris, including leaves and plant material; remove all debris.
• Prune overhanging tree branches and foliage to reduce leaf litter.
• Inspect for evidence of animal, bird, or insect access and identify and seal any access points.

Every 2 - 3 Years:

• Inspect the inside of the tank for accumulated sediment.
• If sludge is covering the bottom of the tank, siphon it out or fully empty and clean the tank as required.

When purchasing a new tank, in Queensland all new tanks must be fitted with mosquito-proof screens and/or flap valves on every opening, including overflows. The screens must be made of brass, copper, aluminium or stainless-steel gauze, have a mesh size of 1mm or less, installed in a way that does not cause or accelerate corrosion and stops mosquitoes passing through the openings. Flap valves must be able to stop mosquitoes passing through the openings when they are closed.

For further details, please call Council on 1300 007 662.