More than a million litres of recycled water has been safely retained on-site at our home since 1996. During all those years it has been re-used for toilet flushing, clothes washing and gardening. We've experienced no human illness or injury from the system, and the soil in the wetland where surplus water is absorbed is healthy, supporting a range of vegetables and
other productive plants.
A key to my home's astonishing
water efficiency and waste disposal
is a nifty low-maintenance recycling system that lives under our back
deck. I refer to our so-called wastewater as 'recycled' or 're-used' water because it's far from being a waste. Instead,
it's a valuable resource.
About half of a household's water is used for flushing toilets and washing clothes. Re-using wastewater more than doubles the time you can use your rain tank, because it makes that water last longer for drinking and washing purposes.
All the dirty water from our house – 'grey' from the shower, bath, dishwasher, washing machine, sinks and tubs and 'black' from the toilet – drains into
a single sewer pipe that empties into an underground concrete tank.
Inside the tank are four tanks. The first tank receives all wastewater. When this tank is full a pump automatically pumps some of the water from the top to three other tanks. Air is pumped by an aerator 24/7 into the first two of these three tanks. That air creates an environment to sustain life of small critters which eat the waste in the water and clean it. The oxygen from the air keeps the water from smelling. Water is pumped from the final tank by another pump whenever the toilet is flushed or clothes are washed or the garden is hosed. As the water is pumped from the final tank it goes through a sand filter and is sterilised by an ultra violet lamps so viruses and pathogens are not present in the final, used water.
The water exiting the other end of the tank is clean enough to be re-used in the house as greywater to flush toilets, wash clothes and water the garden. Any excess overflows into a coiled leaky pipe a metre below the garden. The water looks clear, has no foul smell and is clean enough to drink (although this is not done or recommended) ... and shirts from the washing machine look just as white and fresh as those from the best suburban laundromats.
The system did suffer three smelly breakdowns during its first year and was redesigned to the system described above - called, an 'aerated' system.
The water recycling and sewage disposal systems in my Sustainable House annually process about 100,000 litres of sewage, preventing it from entering the Pacific Ocean.