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.

Designed for a young family, the brief was to create a warm and sunny holiday retreat for extended stays. Open plan living areas, minimal energy requirements and a house operating off the grid were highly sought after initiatives.

What has resulted is a 70.5sqm multifunctional house that comfortably accommodates two adults and their child. Celebrating industrial finishes, including natural concrete, glass and timber, contrasted with a high glass lacquer red finish to the bathroom, the design mixes Alaskan self-sufficiency and a simple Japanese aesthetic – mirroring the cultures of its owners.

This rural retreat, cloaked in a ‘yes, we can’ attitude, is now completely off the grid, utilising photovoltaic solar panels, rainwater tanks and a waterless toilet to ensure a minimal energy footprint. Central to its energy and resource efficiency is an effective utilisation of water management systems.

Water plays a big part of our lives (not least because it sustains life itself), and keeping a constant supply of fresh water is a luxury most people in Australia can afford.

However, this project has challenged the conventional reliance on available water supplies, and features four main integrated water management systems – Rainwater, Stormwater, Greywater and Blackwater.

Moreover, water conservation was deemed even more critical as having a small roof area meant that water collection was heavily restricted.

“The key challenge lay in careful investigation, research and analysis to ensure that the specialised systems used would achieve maximum efficiency to conserve the use of water and power generated by PV panels,” says architect Ric Butt of Strine Design.

The rainwater system uses a 28,000 litre Pioneer ‘rural design’ rainwater tank with a PV compatible Grundfos pump, which ensures that the pump does not come on for every use of the tap, thus conserving energy and Photovoltaic batteries.

“We used a standard gutter and a charged Downpipe and Stormwater system,” adds Butt. “The advantages of a charged system are that there are no overhead pipes and plenty of Downpipes to ensure no water is wasted.”

For the stormwater system, larger 100mm pipes were used to ensure that a greater capacity of water was getting to the tank during torrential downpours. This minimises the possible loss of water, as standard pipes might not be able to cope with a large gush of water.

The architects also considered the kitchen and laundry areas when designing the water management and plumbing systems. Kitchen waste water, treated as Greywater instead of Blackwater, first goes through a grease trap before proceeding to a Clivus Multrum Greywater Prefilter.

On the other hand, the bathroom and laundry water goes through a Greywater Prefilter, then on to an absorption trench.

The most striking facet of this project is its waterless composting toilet from Clivus Multrum. According to the architects, this Blackwater system is suitable for remote locations, and only requires a moving fan. The system is aerobic, as opposed to anaerobic, and the fan ensures that fresh oxygen is always moving through to facilitate optimum composting and minimal odour.

“The maintenance [of the system] includes minimal water, all kitchen compost improving healthy bacterial growth, and depending on use, some rearrangement of compost material,” says Butt.

While it was difficult to get local council authorities to approve the waterless composting toilet system, Clivus Multrum is an accredited system certified by the Health Authority of each state. The project has since surpassed mandatory requirements.

How Clivus Multrum waterless composting toilets work.

How Clivus Multrum waterless composting toilets work

The Krawarree House might seem bare at first glance, but it is far from being barren. Featuring a simple and modest design, it offers architects and homeowners food for thought on how to manage their water and plumbing systems.

Closely following the old Australian adage of, ‘if it moves it will more than likely break (and need repairing)’, the Krawarree House is a great investment for all the right reasons, with the Clivus Multrum system alone helping its owners save up to 60,000 litres of water each year.

Clivus Multrum waterless composting toilets

Water management: elevation showing the Clivus Multrum underground inspection chamber at the Krawarree House

Water management: elevation showing the Clivus Multrum underground inspection chamber at Krawarree House

A self-contained, odourless toilet treatment system, the Clivus Multrum waterless composting toilet uses no chemicals, heat or water, and has no polluting discharge.

The toilet is based on one of the oldest principles in nature – simple organic decomposition – and its composting process and care requirements are similar to a regular garden compost pile.

Waste is collected into the composting chamber along with carbon rich material, such as wood shavings and garden wastes. Here, the materials gradually decompose in the ventilated environment.

Baffles and air channels in the tank distribute air flow, helping to aerate the pile. This promotes the aerobic composting process.

A small electric fan in the vent pipe also creates airflow within the system and ensures that the toilet room is always kept clear of any odours from the processor.

As the organic material decomposes, it will reduce 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.

To find out more about this product or contact Clivus Multrum, please click HERE or visit www.infolink.com.au/c/Clivus-Multrum-Australia.

Photography by Cameron Wilson

Geraldine Chua

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