DesignEnergy Systems

How to get a Hot Shower out of your Compost

Anyone that has been invested in permaculture or who is beginning to broaden their horizon on the topic will know that bacteria are to be revered. For example, nitrifying bacteria break down ammonia and provide us with healthy aquaponic systems while anaerobic bacteria can provide us with hot showers, yes, nice hot showers, as well as rich compost.

Compost heaps can provide hot water for showers for up to 10 months. The plant matter that is used for a compost pile can include the off-cuttings of trees in the area that need to be controlled due to fire risk. This assists in fully utilizing available resources and the same can be done for any area.


Firstly, a compost heated shower is best for an outdoor shower. It allows for further optimization of resource use by enabling the water from the shower runoff to water plants. You can choose to channel this or to build your outdoor shower in a location that needs to be watered morning and evening. The water source used for this will need to be adequate to push the water through one hundred meters of poly pipe. This amount of piping should not be shortened as the coils of pipe layered in the compost all absorb the heat provided by the compost for the water to be heated.

Take 100 m of 20 mm poly pipe, the various valves and joiners that will be needed for your particular shower design and have ready a compost thermometer and about six cubic meters of freshly mulched wood chips or whatever plant matter would be best for your given area. It is necessary to make two compost heaps that can be switched between as the first heap begins to cool and vice versa once the first one is rebuilt. Valves that allow you to change the source of your hot water are essential for this. Be careful with your connectors and your poly pipe. If leaks develop the water that seeps into the compost will drown it and prevent the temperature from rising.

CompostThe idea is to layer coils of the poly pipe between layers of compost. It is important to create an anaerobic compost heap, so the air will need to be pushed out of the compost heap as it is layered over the coils of poly pipe. Water the heap and tamp it down as you go to achieve an anaerobic compost heap. If you find the temperature rises too quickly, the compost heap is attracting anaerobic bacteria, so it needs to be better compacted and watered.

Make sure that the pipe is not in the center of the heap, though, as you need to place a compost thermometer in the center to keep an eye on the temperature of the compost heap. Smell shouldn’t be a problem with plant-based compost, although some particularly sensitive noses may be able to detect something. Reassure them that the poly pipe may pick up a scent, but nothing more.

To make sure that the pipe is properly insulated and will be provided with enough heat at all points, allow for about 20 cm of mulch for each layer of compost and make sure that the coils of poly pipe are not exposed or not insulated with enough compost. Leave to bake for about a week and expect a cozy 45 ℃. If you find that the temperature doesn’t rise, check to see if the compost heap is either too dry or too wet.

And there you have it. The perfect heat source for an outdoor shower that effectively makes use of natural resources that further provide sustenance for living plants by feeding and watering them while keeping the humans that tend them squeaky clean.

Check out Geoff Lawton’s compost heated shower in the Youtube clip below. Enjoy!

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