Compost Water Heater With The Jean Pain Method

Photo:  Katrina Spade | License: CC BY-NC-SA
Photo: Katrina Spade | License: CC BY-NC-SA

For those of us who have successfully composted in the past, we know that a properly made compost pile produces a substantial amount of heat. In fact, when the pile stops creating heat it is usually done “cooking” and ready for the garden.

We focus a lot on leveraging technology to become more resilient. So what can we learn from a Frenchman who died over three decades ago?

A lot!

What is a Compost Water Heater?

Simply put, it’s a giant pile of compost with tubing that is coiled throughout the compost pile and then filled with water. The water within the tubing heats up substantially (and relatively quickly).

Compost Water Heater

Jean Pain in the process of building a compost water heater

To give you a glimpse of what a real-life compost water heater is capable of, here’s Ben Falk at Whole Systems Design in Vermont showing off their first generation compost water heater:

They used a mix of wood chips and horse manure to build this compost water heater, and got hot water with temperatures of 140 – 145 degrees Fahrenheit (~ 60 degrees Celcius). Not bad.

Who is Jean Pain?


Jean Pain was a French innovator who lived in southern France from 1930 until his passing in 1981. He was able to create a compost-based energy production system that was capable of producing 100% of his energy needs.

Using compost alone, Jean was able to heat water to 140°F. He used this water for washing, cooking and heating his home. We aren’t talking about a small amount of water either. His system was able to heat water at a rate of 4 L per minute; or almost 1 gallon per minute.

Many of our modern hot water heaters can’t even boast figures that impressive.

In addition to heating water using compost, Jean also distilled methane to run a generator, a stove, and fuel his vehicle.

The work he did is still viable today. Sometimes known as Jean Pain Composting or the Jean Pain Method, we can learn a lot from the work of this Frenchman about resiliency.

Interestingly enough, just about all of Jean’s work is in French. There are English translations available around the Internet, however, so with a little bit of research we can take advantage of Mr. Pain’s successes as one of the early innovators of modern resiliency.

If you are interested in learning more about the work of Jean Pain, check out the book entitled “Another Kind of Garden.”  It is translated from the original French so it is a little hard to read, but the information is extremely interesting and we could all learn a thing or two from his work.

How Does it Work?

It may seem unbelievable that a simple compost pile filled with anaerobic bacteria could heat water to temperatures hot enough to scald skin. It is, however, entirely possible and easily replicated at home.

You only need to search YouTube for a few minutes to find thousands of videos detailing variations of Jean Pain’s design being used in towns and cities around the world.

As mentioned, the basic idea behind a compost water heater is that tubing is coiled throughout the compost pile and then filled with water, which in turn is heated by the compost pile.

As the below image illustrates, cold water goes into the coiled tube and hot water comes out. Not only that but it’s also possible to extract methane gas from the compost pile, which can then be used for cooking or heating.

Thermal compost pile

Looking back at the work of Jean Pain, his compost piles built with wood chips were massive. In some cases, he was employing 60 tons of compost in a single pile to provide his energy needs. More recently, however, experiments have used piles that are as small as 6’ x 6’ to create a similar effect. Some of these modern piles are producing temperatures of 150°F or more.

The trick to improving the original design is the use of more polyethylene tubing. In the typical 6’ x 6’ compost pile mentioned above, you might expect to use at least 300 feet of 1 inch diameter polyethylene tubing. This tubing is carefully coiled and layered in between the layers of compost to repeatedly heat the water as it moves through the various layers of the coil system.

As a general rule, the pile will start with a compressed layer of compost followed by a layer of coiled tubing followed by a layer of compressed compost until you reach the desired height.

Since a compost water heater does not have a hot water tank, the tubing becomes the “tank” in this example. This means that the more tubing you use, the more hot water you will have available at a given time. Think long, relaxing shower versus being the last one in the house to get a shower before work.

Although the original designs of Jean Pain did not include a hot water tank, there has also been some interesting research done in the last few years where this technique is combined with the use of a conventional hot water tank as a way to preheat water entering the tank. This is an excellent way to save on your energy bill without relying completely on the benefits of a compost water heater.


Once the decomposition process is functioning properly within the compost pile, you can expect several weeks of reliable water temperatures. In the early 80s, Mother Earth News tested a design very similar to Jean Pain’s system and was able to achieve consistent water temperatures above 130°F for several months before the heating action began to dwindle.

The length of time your compost water heater provides a reliable energy source depends on its construction. Not only do you have to consider how large your pile will be, but the ingredients you put in it and the amount of tubing you use are also considerations when designing your own compost water heating system.

Additional Thoughts

Based on the experimentation of others, there are a couple of things you want to keep in mind if you decide to create your own compost water heater. First, try to locate the compost pile near the intended usage location. Obviously, heat is lost as the water travels across large distances.

Some people have created separate outdoor showers that are located just a few feet from the compost water heater.


As previously mentioned, you could also consider using a compost water heater as a way to preheat water entering your hot water tank. This is often easier than implementing a standalone compost heater and it will save significant amounts of energy typically used to heat groundwater in your hot water tank.

Other people have also used compost water heaters in conjunction with various solar water heating techniques. Although a compost water heater is a very effective solution by itself, the power of the sun makes it an even more reliable option.

Thinking of Building Your Own?

Creating a compost-based water heater is excellent weekend project. The only things you really need are compostable material, an area to devote to your compost pile, and lots of polyethylene tubing.

There are tutorials all over the Internet detailing various methods – some work very well while others fall short of the performance achieved by Mr. Pain himself.

One of the most important things to remember when creating your own compost water heater is to compress the compost pile very well. Since anaerobic bacteria are responsible for heating the pile, the more compressed your compost is, the better your water heater will work.

Another thing that some people have done successfully is create two small piles with tubing coiled in each of them. In areas where space is limited, this may be a good alternative that will still heat water practically as well as a single large pile. Truly, the key is to use lots of tubing and coil it throughout the compost pile – as long as you do that, you should have no issues heating up your water to 130°F or better.

With the cold winter months fast approaching in many parts of the country, the idea of hot water that does not require any external energy source is a welcome solution and an idea we should all think about incorporating into our current resiliency plans in the near future.

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  • Vertis Bream

    Do I have this correct? We take a humongous amount of organic matter (from where?) and pile it up and allow it to heat via anaerobic (unnatural) up enough to burn until all that is left is a high humus ash; meanwhile, dumping tremendous amounts of CO2 into the atmosphere. Doesn’t sound like a sustainable practice for resilient folks to use. Isn’t/wouldn’t it be better to use all that OG as a mulch slowly breaking down as nature intended and feed soil microbes/livestock instead of anaerobic bacteria?

    • Jesse

      anaerobic is not unnatural, where did you get that idea? Both anaerobic and aerobic respiration produce CO2. many of the soil microbes are anaerobic bacteria. The article stated that a 6’x6′ plot is large enough, which is not a humongous amount. If you used the compost to feed livestock you would also be producing large amounts of methane, which is 23x more potent of a green house gas than CO2. So where exactly is the logic in your comment Vertis Bream?

    • richard

      An anaerobic organism or anaerobe is any organism that does not require oxygen for growth

    • joe

      You put out a lot of CO2 also, maybe you should stop breathing.

    • mark tompkins

      Al Gore is going to become the first carbon tax billionaire. Quit sitting on your heads people. I am a professional engineer who worked for 7 years in the oil and gas industry, and the “inconvenient truth” is that global warming is really intended to be a great reason to shut down coal powered plants (i.e. deindustrialization and the death of the middle class in Amerika). It is COMPLETE BS CRAP!!! Which also has the side effect of increasing the value of petroleum assets (duh!!!) It should be no surprise that Al Gore is/was the largest shareholder in Occidental Petroleum (g0 check).

  • James Early

    I am wondering how effective this would be in the winter when my compost pile is not active.

    • Patty

      Compost IS active in the winter. The composting and heat being generated is within the pile – where the water coil would be.

  • Mary Saunders

    Undiscussed here is that you need a proper carbon/nitrogen ratio.

  • Marty

    toQuite the opposite, Valerie. This is basic Biochemistry 101. I don’t know where you got the idea it would be some toxic, horrible thing once it is done “cooking”. On the contrary… what is being created by the compost is a wonderfully rich garden soil. I raise a small flock of chickens. I compost the chicken manure and, ultimately, it becomes rich, nutrient laden, garden soil in which I grow luscious, organic vegetables. No additional fertilizer required. Talk about sustainability… this is truly the definition of the circle of life. The chickens, in turn, eat some of the things I grow, and the circle continues.
    The whole thing about the heat is that you cannot put the compost onto yourgarden

  • Marty

    Your garden too soon…before the temperature comes down or it will kill your plants. That’s the point of the microbes doing their jobs…breaking it down to a usable level.
    Harnessing the heat from the process is absolutely brilliant.

  • Martin P. Hellwig

    The source of the heat is NOT the anarobic digestion, but the opposite, aerobic. It is the same principle on why spontaneous self combustion occurs in Haystacks.

    Therefore it is important that for the heat generation there is plenty of oxygen available.

    Anarobic digestion is thought by many to be even slightly endothermic (i.e. requiring heat).

    The methane/gas is produced in a closed container inside the main pile. The main pile has access to oxygen, thus aerobic digestion will occur, producing heat and CO2 from the feedstock. This CO2 is vented into the air (you should vent this into a greenhouse to encourage plant growth) and the heat transferred to the tubing and the closed container.

    The closed container, not having access to oxygen will start anarobic digestion, thus from the feedstock produce ‘swamp’ gas.

    Beause a lot of heat of the main pile is lost to the ground and outside venting, it can be improved by placing it in an closed insulated container, however this will make arobic digestion problematic, since the oxygen will be consumed rapidly.

    This can be solved with airpumps but now the process becomes more labour intensive as you introduce more point of failures.

  • Vertis Bream

    I never said that the end result would be horrific or toxic. The result would be a small pile of humus and mineral ash. Humus and minerals are good. I’d rather see a better use of the OG. Of course, anything that happens is a “natural” process of some cause and effect. My use of the word natural was as in the way mother nature works. A 6 X 6 X 4 pile of OG would provide an 850 sq’ of bed with a year’s worth of sustainable mulch or 350 sq’ of permanent mulch. The benefits of nature’s sheet composting process far out weigh the practice of adding ammendments including imported (not insitu) compost. If you were to spread the resulting compost from the 6 X 6 X pile 1/2″ deep; it would cover about 200 sq’. I also use chickens both in chicken tractors and on a rotational basis in the garden. They spread their manure for me. Microbes reduce the manure to humus in 4 days. All the nutrients remain and that all important humic acid helps me to grow 1/4″ of topsoil per yr.

    No one has addressed my question of where that pile of OG came from. It certainly can not function as its original intent since it has been removed from somewhere else. For heating purposes, I find that wood (A much denser version of OG) used in a hot burn (ie:rocket stove) is a much more efficient use of photosynthesis and the root zone. Then we also have the forest understory crops. Solar heating when/where possible is my fav choice.

    As to the comment that a 6 X 6 pile is not humongous… I was referring to Jean’s (the focus of the article) 60 tons of compost for his energy needs. The small pile will not provide heat for very long. You need a lot more mass. I’ve produced 140 degrees in a well mixed/proportion/turned 4 X 4 X 4 pile; but it only lasted 2 weeks. Hey, I’ve done plenty of this stuff 40 yrs ago. However, let’s just stay with the 6 X 6 pile. I don’t even consider that a small amount of OG. If we use grass clippings; that is 72 walk behind mower bag loads. That is a lot of grass. I’ll head off all of the responses coming about importing somebody’s waste rather than robbing from your own plot. I still see a lot better use of imported “wastes” (There is or should not be such a thing as waste carbon). It’s most efficient and natural use is in a permanent mulch or hugel culture.

    • LB

      In terms of waste carbon there are several sources that occur that would be suitable for this purpose and could be a beneficial alternate use than is currently utilized. I made one of these piles many years ago to test this concept out. I found that using wood chips from tree trimming operations provided the best and longest lasting carbon source for the pile. At the time I used commercial Urea as the nitrogen source to break down the wood chips. Today I would use others sources such as poultry manure. The pile lasted all winter and then some as the wood chips take a long time to break down. You can source wood chips from local tree companies or line clearance crews and the usually will deliver them to your property, gladly. The piles are easy to make with the chips and you end up with a tremendous supply of organic matter in the end. You will want to use some of the material in next years pile as it will not all break down the first year. So, a material that is not always used to its fullest potential is recycled and improves you land tremendously. I have two loads being delivered by Asplundh in 2 weeks.

      • LB

        I would add that the 2 loads being delivered will be used as a deep bedding in my cattle barn this winter and next summer. The animals will add the nitrogen source for me and once piled the bedding/chips will activate immediately. My goal is to use the pile to heat a High Tunnel for growing winter vegetables.

  • jamie

    hi, I am currently in the process of applying for up to 6 holiday lets of my farm in Exeter (uk). we are planning on making them as eco-friendly as possible. we have decided to build from straw and other sustainable or recycled materials. we are planning on installing solar panels for electricity and reed beds for the sewerage system. I then stumbled across the composting water heating idea and think it’s great. Being a livery yard we have plenty of muck which we can continuously add to maintain the heap.

    I am wondering how I would set it up and whether it is a viable idea to at least help in heating some of the water. is there some sort of container system where by I could remove the already composted manure from the bottom allowing more to be added from the top. I would love to see the system already working somewhere else, if anyone has one nearby. any help or advise anyone has to offer me would be much appreciated.

  • Dan Robinson

    A somewhat related technique, for emergency situations like storms, earthquakes and such, does anyone, or everyone, know about “counter-current heat exchange” to disinfect water? It can be heated enough to sterilize it with much less heat input than might be expected, by having the output water heat the input, with the two flowing in opposite directions. Ideally, one long, straight pipe inside the other, such as 3/8″ tubing inside 1/2 pipe, and good heat insulation surrounding the pipe. This is much more effective than having input and output water flowing in the same direction. The longer the pipe, the more effective heat transfer.

    Some microbes require 240 F degrees , the common temperature of pressure cookers, to kill them. So if the cold end of the input and output pipes is high above the heated end, perhaps 10 feet, this temperature/pressure can be reached at the hot end. Until you’re sure it’s doing the job, water should be tested before and after heating. If not sufficient, use longer pipes.

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