Incurring no electricity, sewage or water bills seems like an unattainable dream, but the Krawarree House by Strine Design demonstrates that this fairytale can come true.
At 70.5sqm, this rural retreat is completely off the grid, utilising photovoltaic solar panels and rainwater tanks to ensure a minimal energy footprint. Contributing to the site's low resource wastage and energy efficient water management systems is the Clivus Multrum waterless composting toilet system.
According to architect of the project, Ric Butt, this Blackwater composting toilet system is suitable for remote locations, and only requires a fan which ensures fresh oxygen is always moving through to facilitate optimum composting and minimal odour.
“The maintenance includes minimal water, all kitchen compost (improving healthy bacterial growth), and depending on use, some rearrangement of compost material,” says Butt.
The composting process here works similarly to an ordinary garden compost bin. Waste is collected into the composting chamber along with carbon rich materials such as wood shavings and garden waste.
This organic bulking matter is needed to absorb all liquids, as well as to give the composting pile a friable texture that ensures sufficient aeration.
The carbon rich organic bulking material furthermore maintains the carbon-nitrogen ratio at an optimum level of the micro organisms, thereby creating an environment that optimises the decomposition process. It also helps prevent the release of excess nitrogen in ammonia.
In addition, baffles and air channels in the tank distribute air flow, helping to aerate the pile. This promotes the aerobic composting process.
As the organic material decomposes, it reduces in volume by up to 90 per cent. The compost pile is therefore always ‘shrinking in the middle’, whilst new material is being added to the top. Finished compost is removed from the bottom of the pile when appropriate.
Utilising the Clivus Multrum for this project has meant that water is not needed, saving the owners a substantial amount in water bills. It has even been found that the system enables households to save more than 60,000 litres of water per year.
Environmentally benign, the Clivus Multrum waterless composting toilet system is a long-term, low maintenance investment.