7 October 2010 – Sustainable House is an update on the original book by Michael Mobbs, published in 1988, and a warts and all account of what worked and what didn’t work in converting his typical inner city Sydney terrace into an environmentally friendly house that could make its own power, capture its own water and recycle its sewage . At least most of the time.

It contains advice on how to select and upgrade facilities and also on how to deal with councils, builders and engineers, and the costs and benefits associated with the sustainable options.  There are assessments of the features. Did the solar panels last? Is rainwater in the city safe to drink? How has the garden handled over one million litres of treated sewage?

Also included are case studies of other sustainable houses.

Publisher New South Books  has offered a 20 per cent discount off the $45 RRP,  available  by visiting here

Extracts from Sustainable House

It’s rained a lot in Sydney this year.

But no rain water or stormwater has left Sydney’s Sustainable House in the storms this year or for the last dozen years.

The house is about 10 minutes walk from the centre of Sydney’s CBD.  It’s a 19th Century terrace with a garden about 10 square metres, three bedrooms and from the front and inside it looks like any other inner city terrace.

The house is disconnected from mains water and sewer.  It harvests rain water for drinking, cooking, hot water, and reuses treated sewage for toilet flushing clothes washing and gardening.  Energy during the day is from the sun.

But it’s just an ordinary house to live in and folks turn on switches and taps there just as they would in any other house.

So far, in 14 years, the house has:

  • kept over 1.5 million litres of surplus sewage here in a garden some three square metres
  • produced such high quality and low quantity sewage that a leading soil expert says the garden’s good for another couple of decades of sustainable water use like the last 14 years
  • stopped over 112 tonnes of greenhouse gases polluting Earth’s air
  • left over 1.5 million litres of water in the dams
  • stopped over 1.5 million litres of stormwater polluting Sydney Harbour
  • stopped over 56 tonnes of coal being burnt
  • saved over $42,000 in water and energy bills

How has the house done these things?  In summary:

  • A 10,000 litre concrete rainwater tank harvests all rainwater which is used for drinking, cooking, showers, baths, hot water;
  • A 3000 litre concrete tank treats all blackwater from all wastes and sterilizes it for reuse for toilet flushing, clothes washing and gardening (the system integrates an aerated water treatment system, filters (with sand and granular activated carbon, and ultra violet light)
  • 8 solar panels make electricity for the house or, if unused, to sell back into the main electricity grid
  • a solar hot water heater with a gas booster makes the hot water
  • a sunken pond absorbs all surplus rainwater, and surplus sewage is discharged after treatment about 1.5 m below ground for absorption there.

There’s a handy website on the ABC’s site with more details about the house and how it works.

All the products are available around Australia at local hardware stores or through local suppliers and can be installed by local trades.  No special skills are required to live here and the house is very ordinary – just like anyone else’s except for what’s on the roof or under the ground and out of sight.

Sewage disasters

Of all experiences with the sustainable systems installed here, the waste system has brought the rawest and worst moments of the experience. But it has also given us the greatest learning experiences.

The sewerage treatment system was badly designed and poorly built. It failed and its designer company and installer went broke, and we were left alone to find solutions.

This turned out to be a fabulous education for me – I doubt it’s offered by any TAFE or uni – and I feel lucky to have had it. In particular, I have learnt to ask questions then follow them up by touching, feeling, seeing, smelling and testing these systems. Now, only these “seeing is believing” tests satisfy me –  not brochures, test results, and other indirect information.

Now I know the right questions to ask.

About two and a half years after it was installed, when the system had a heart attack, the water went foul, dark and smelly. As the designer and installer had gone out of business, there I was, high, smelly and not dry, with urgent unmet needs to manage the house’s daily sewage.

Upon opening up the tank I discovered the design and building faults. It was clear that:

  • the system was not aerobic because there was no air inlet device, and the outlet device was not working, and probably never had (for a discussion of aerobic and anerobic treatment see later in this chapter)
  • the different filter media beds had collapsed upon each other and congealed into an anerobic, vile and useless mess
  • the different beds were not modular, almost impossible to get out without a weapon of mass destruction and almost impossible to get at, below or from above, and too heavy to remove even for the strongest person
  • there had been a build up of sludge at the base of the tank.

This was a moment offering broad opportunities for personal growth and, mostly, I took them. I apologise to those who were involved where I did not. It is, however, my experience that it’s healthy to express my anger so I did, loudly, in the shower, walking down the street, on the phone and anywhere I could, given that the authors of my growth opportunity were not there to share this journey.

Still, I have a deep confidence now about what works and doesn’t when treating sewage, and I have become even more curious about sewage, and more ‘at home’ with it. Otherwise, I’m normal.

After a week of swearing, sweat and faeces the failed treatment beds were removed. (A shovel and a bucket were used instead of weapons of mass destruction.) Never again will I use something to treat waste which is not modular, easy to disassemble and which is incapable of easy maintenance.