Water

Filtration and treatment

Although leaf screens and first flush diverters help provide cleaner water in a rainwater collection tank, it is still possible for bacteria, viruses, algae, pesticides and other contaminants to be present. Filtering and/or treating the water can greatly reduce the presence of these. Treatment can also help remove unpleasant odours.  

Filters

Filtration systems can treat all the water entering the house from a rainwater collection tank, or can be fitted under a kitchen bench to just provide cleaner water from one tap.

Different types of filters do different jobs. Typically, a 1 micron cartridge comes first, and this can filter out some organisms such as Giardia cysts. It also reduces any sediment, dirt and rust that may be in the water. This can help keep the inside of household tapware and appliances clean, but importantly, it also helps extend the life of the second filter.

The second stage filter is typically a carbon filter that can significantly reduce the numbers of bacteria in the water, remove some chemicals, and reduce unwanted tastes and odours.

Filters occasionally need replacing; how often depends on water use.

Ultraviolet treatment

With these systems, water is exposed to the light from ultraviolet bulbs. This light disrupts the DNA of microorganisms such as bacteria and viruses, stopping them from multiplying and thereby reducing their potential to cause illness. Common pathogens such as E. coli, Cryptosporidium and Giardia are all affected.

Ultraviolet treatment systems are sometimes installed in conjunction with filters. Ultraviolet bulbs need replacing when they are no longer functioning.

Ozone treatment

Ozone treatment kills microorganisms such as E. coli, Salmonella and Listeria. It can reduce pesticides in water and also remove unpleasant odours. As with filtration, ozone treatment systems can be installed that treat all water coming from a rainwater tank, or can be installed under a kitchen bench to provide treated water from a single tap.

^{Updated: 22 June 2015}