Domestic rain water tanks have been successfully used in Australia for many years as the primary source for drinking and general usage water without any major health risks. The two major issues that can affect water quality are as follows:
1. The presence of rotting vegetation that is captured in the system and can result in discoloured and foul smelling water and a build up of sediment in the bottom of the tank.
2. The presence of faecal coliform that is introduced through faecal material from birds and small animals or decomposing animal carcases in the collection path or the tank itself.
A well designed collection and storage system incorporating the following guidelines will help minimize any problems.
- Regular inspection of roof collection area, guttering and down pipes, removing any leaf matter and debris. Blocked down pies and gutters can be a major breeding area for mosquitoes
- Fitting of gutter guard may be essential if you are in an area with trees located near the roof area. This will provide additional benefit in case of bush fires
- All down pipes in the collection path should have a rain head (or frog mouth) fitted
- An essential element to any collection system is the fitting of a first flush device. After a dry period rain collection areas can often be covered in dust and other airborne pollutants, a first flush device will collect these before filling the tank.
- Insect proof mesh on all inlet and outlet openings (inc overflow)
- Light proof inlet screens with a lift out strainer
- Removal of any tree branches overhanging water collection areas
Healthy tank water should be clear and free of odours and the first indication of any problems with the quality of your water could be either discolouration and/or odours and while this in itself may not be an indicator of a significant health risk caution should be observed. If you have any doubt avoid all contact with the water until the cause of the contamination has been identified and removed. Treatment can range from simply desludging your tank to disinfection using a chlorine additive.
Where water from your rainwater tank is to be used for drinking and food preparation the use of an inline filter or a UV light is recommended.