A heating system developed by a French innovator decades ago is gaining a new life as a sustainable way to get free hot showers in the modern world.

The annual build of the compost shower has just been completed at the Fair Harvest Permaculture Farm in Margaret River WA.

The system was developed by French innovator Jean Pain (1930-1981), who used compost to meet all his energy needs.

Fair Harvest has perfected the anaerobic compost technique over recent years, with the pile providing hot water for the outdoor shower for 10 months.

Start with a big pile of wood chips. These were harvested for fire control around the Fair Harvest Permaculture Farm in Margaret River. ( ABC News: Roxanne Taylor )

Build the compost pile layer by layer, being sure to dance and jump to compact it as you go. This photo was taken on the second day of a three-day build. ( ABC News: Roxanne Taylor )

Many hands make light work: the more friends you can get together, the more it becomes fun. ( ABC News: Roxanne Taylor )

Keep it really wet as you go. The moisture will kickstart the composting process. ( ABC News: Roxanne Taylor )

Compact it as much as you can. This will remove the oxygen from inside and create an anaerobic composting process which is slow and long lasting. ( ABC News: Roxanne Taylor )

Coil the poly pipe through the compost as you go. This will hold the water inside the warm pile and feed it to the outdoor shower. ( ABC News: Roxanne Taylor )

Put a soft layer of leafy litter directly around the poly pipe to protect it from getting punctured by the rough wood chips. ( ABC News: Roxanne Taylor )

Just keep watering and dancing... ( ABC News: Roxanne Taylor )

Once complete, the temperature of the compost will reach 45C in two weeks and will stay that warm for 10 months, heating the water in the pipe within minutes between showers. ( ABC News: Roxanne Taylor )