Mouse Plague and a Safe Water Supply

Published on 13 May 2021

The current mouse plague confronting many parts of rural Australia can present a serious health threat to your domestic rainwater supply.

There is an excellent guide to metro rainwater harvesting which includes sections on tank prefiltration and first flush diverters etc., the RAINWATER HARVESTING RESIDENTIAL DESIGN SPECIFICATION which can be downloaded here.  The installation of a tank and incoming pipework is the same whether for metro rainwater or for rural drinking water use in rural areas.

Even when rainwater tanks are installed with all the recommended prefiltration precautions, mice and other rodents can have a detrimental effect on your drinking water security, especially in the current plague conditions. Note only can mice sneak into a tank by the smallest of gaps, they can die in your gutters and downpipes, defecate on your roof and attract predators who also add to the biological contaminants entering your rainwater tank.

What can you do to protect your drinking water from contamination?

Protection and maintenance:  

  • Make sure all entries into the tank are either closed or ensure water enters via a filter with a fine mesh.  Mesh with openings of less than 1mm are recommended.  
  • Don’t forget the overflow outlet either – vermin and insects can enter a tank via an open ended outlet.  Use a correctly installed flap valve on the overflow outlet.
  • Clean all inlet filters and gutters regularly.
  • Clean your tank every few years.  If you aren’t sure how to do this safely, use one of the local tank cleaning services.  Ask your local Davey for advice.


Often the first sign you have of a problem with your rainwater integrity is bad odours or taste.  This can easily elevate to illness; particularly gastrointestinal upsets.  Depending on the severity of the tank water can be treated in a variety of ways:

  1. Filtration:  This is important but it won’t overcome the issues by itself.  In any case filtration should be to 1 micron, and preferably in two stages.
  2. Eliminate or neutralise bacteria and viruses:  This can be done two ways and is often both ways are applied together:
    • Chemical treatment:  Water authorities commonly treat municipal supplies using chlorine, but for domestic use this is subject to significant misuse, often with undesirable outcomes.  A much safer option is the use of non-chlorine based proprietary chemicals such as Davey’s Acquasafe.  This is added on a regular basis to the rainwater tank.
    • Ultraviolet (UV) treatment:  This non-chemical treatment method is extensively used for water treatment of all sorts from domestic water supplies to municipal water, from commercial swimming pools through to effluent treatment plants, and lots more uses.  To be effective the water must be filtered to ensure the UV radiation is able to neutralise all the pathogens.  The filter and UV chamber are placed in the pipework after the tank and home pressure system and before the home.  Davey have a range of high quality UV and filtration packages to suit small cottages right up to whole townships.
  3. Taste and odour:  While the use of a chemical like Acquasafe will generally reduce and even eliminate objectionable tastes and odours, adding a high capacity carbon cartridge after the UV system can help to ensure the taste and odour is even further reduced.

While this approach may sound like a bit more than complicated than the ineffective “a single filter will fix it all” approach, remember your health and the health of your family are the most important things in your life.  And safe clean drinking water is one of the main ingredients for good health.

For further advice and help selecting the right system for your needs talk to your local Davey Water Treatment Professional.  For help locating them use the Find a Dealer tab on the Davey website: