Greywater guidelines

In a continent where water scarcity is a common phenomenon, Australia's been taking a lot of steps towards more efficient water usage. During the last ten year drought, strict guidelines were set up for activities such as watering gardens and washing cars, limiting how often and what kind of water could be used. Water saving flushing toilets are standard, as are signs on showers in commercial accommodation suggesting a 4 min or less shower for guests.

This attitude towards water also includes using greywater, which is pretty much recycling water that's already been used, such as shower water, rainwater, and sink tap water. There's some microbial risk from reusing such water (which will be the focus of my upcoming PhD, incidentally), but in general, good water filtration and treatment methods can reduce the risk to acceptable levels. Some examples of filtration systems can be found here from Minnesota Public Radio, which includes septic tanks and concentrated wetlands.

A useful set of guidelines was recently issued from the Australian Clearwater organization on the best ways to harvest and store stormwater (ie run-off from drains or creeks) and roofwater (ie rainwater). These stormwater harvesting guidelines describe how to go about setting up the greywater collecting project, including what kind of roof characteristics to look out for to avoid contamination, types of rainwater tanks and piping to use, and monitoring/maintenance of the project. This might be useful for those interested in using greywater for non-drinking purposes. Other guideline publications from Clearwater can be found here.

What's important though is changing public perception. Many people still have much aversion towards using treated greywater, despite the fact that the microbial risk in the treated greywater can actually be LOWER than the risk in regular tap water. Using greywater is going to become more and more necessary around the world with climate change, but especially in Australia since the continent is already so water vulnerable. So the more the public can understand the process, the better off they'll be.