Compost toilets

Compost toilets save water, energy and nutrients.

We flush nearly one quarter of our household water down the toilet. “At the moment there’s this silly situation where we use high-grade water to flush our toilets,” says planning expert Professor Patrick Troy from the Australian National University. “To cut down our consumption of potable water, we need to change the way we manage human body wastes.”

Professor Troy, editor of Troubled Waters: Confronting the Water Crisis in Australia’s Cities, says composting toilets work with little or no water, and are suitable for suburban and even multi-storey housing. “They can be fitted into standard bathrooms so they look just the same, except they don’t have cisterns and flushes.”

The many different designs – both commercial and owner-built – fit into two broad categories: continuous or batch composting. Continuous systems, such as the Clivus Multrum, use one container. The material decomposes slowly and emerges as finished compost that can be safely dug into your garden. Batch systems, such as Rota-Loo, use two or more containers. Once one is full, it is replaced, sealed and set aside to compost. Commercial systems cost from $800 to $8000, depending on the model and size.

The Environmental Protection Authority accredits commercial composting toilets before they can go on sale. The authority’s code of practice for onsite waste management permits them to be used in both sewered and unsewered areas.

Hamish Skermer runs Natural Event, a business that provides composting toilets for festivals and events around the world. “People can have confidence that these systems meet rigorous standards,” he says. “Composting toilet technology can work anywhere on any scale. If we can do it for 18,000 people at the Falls Festivals, then a family of five can do it in their home.”

Even so, householders often find it difficult to get council approval, usually based on perceptions rather than substantive health issues. But those attitudes are changing: Natural Event has already provided toilets for community events run by a number of Melbourne councils.

Unlike conventional toilets, compost toilets require some maintenance – at the least, to distribute the finished soil conditioner. “They all have to be managed, because it’s not a flush system where it’s taken away and it’s someone else’s problem,” Mr Skermer says. The toilet should not smell. If it does, it’s a sign that something isn’t right. But he says that householders can easily fix any issues by attending to the drainage or ventilation, or adding cover material such as sawdust.

He argues that pee and poo shouldn’t be even referred to as waste. It’s the line of thought most recently popularised in The Humanure Handbook, by American writer, Joseph Jenkins. “We have to understand that shit ain’t shit,” Mr Skermer says. “Waste does not exist in nature. The mere concept of a toilet being ‘waste management’ is a backwards thought.”

Compost toilets not only dramatically reduce water consumption, but also cut the energy required to pump sewerage (currently powered by heavy-polluting brown coal) and return valuable nutrients to the soil. “Our food contains nutrients in the form of nitrogen, potassium, phosphorous and all the trace elements,” Mr Skermer says. “We eat and then pee and crap into the sewer system and a large amount of these nutrients are pumped into the ocean. We’re removing ourselves from the cycle.”