nspired by the warmth of rotting leaves, groundwork of Jean Pain and others, allow me to present my compost water heater. To me, this strategy embodies the idea of permaculture. Heating water represents a huge portion of most people's energy and environmental footprint. Many of us also have a need for compost in these volumes. Why not use it to cut our energy costs and the resulting hidden costs of heating our water. One of the many nice things about this strategy is that you typically dont need a new water heater. Compost water heating in this example is really more of a pre-heater. Water coming out of the ground is typically around 40-55F. Then a water heater, usually powered by burning fossil fuels obtained through mining or fracking brings the temperature all the way up to 110-125F. Thats a big jump, requiring enormous amounts of BTUs or energy. Of course you dont need a "backup" water heater and can just use water raw from the compost pile. In the summer, I will probably attempt this as I dont take hot showers when its hot out. Most of the time though, I treat myself to indulgent showers. Very long, hot and wasteful. Its my important "hot shower yoga" session and I dont plan on adjusting my lifestyle anytime soon. Four months into building my first pile, Iam still getting 68F water from the pile. In power outages (on city or gravity supply) or more "roughing it" situations, this water is going to feel pretty good compared to more available sources. Iam hoping its stays in this range for a full 6 months, when I will change out the pile. I got 100 degree water the first month, 90 degree the second and 75 the third so we seem to be leveling out a bit on month #4, but who knows maybe it drops below 60 soon, still a big improvement to the 42 I just measured coming out of the ground. I may be creating a compost water heating website, more detailed blogs and a Youtube video on the tear down and re-build as I lost the first version with my gopro to the bottom of the Gauley river. Woops, leashes are important after all.. Anyways check back for that and I will jump into the construction and some details with the pictures.. Most sites and situations are not as good as mine. I compost in my backyard that is downhill from my drive/delivery spot, behind my walkout basement which contains the existing water heater. The garden and orchard is also downhill from there. This project was delayed forever with my CMU basement exterior insulation project and finish grading improvements. Sorry neighbors of Montford! Here's the finished pile. The diameter is 6' using 6' tall fencing, and its probably closer to 4.5'-5' tall. I put the it against the foundation wall opposite the water heater in the basement, the closer the better. This also should keep tubes safer from freezing from low maintenance or eliminates underground tubing which would need insulation. The foundation is some scrap roofing underlayment on top of 2" XPS, which is also what I used in two layers to wrap my CMU basement prior to finish stucco. The giant, silver-leaf maple has been a tenacious predator of my compost piles despite the plastic I always put on the ground to protect it. Anywhere the pile spills over the top of the plastic, the maple roots quickly invade. I attached the fence to the ~1" thick stucco with AL termination bar and tapcon fasteners. Because of the slope away from the house, there is lots of weight tugging on this attachment but I was still careful with stomping the pile, trying to force out the sides instead of the downhill opening for a better circle and less weight pulling at the wall attachment. So far so good.. Compost against a home shouldnt be taken lightly. Rodents love the warmth + earthworms and would gladly follow the tubing into the home if you let them. Behind the blue XPS foam is another layer of expanded metal lath, well detailed against the stucco and tubing to discourage tunneling critters. Dont let these penetrations leak air or water either. Seal all penetrations up as tight as possible. Ignore the white pex tube in the middle, I used it to house a temperature probe which is completely unnecessary. Its best to measure the actual water temperature. Since the bottom of compost piles turn to cold soup pretty quick, I built the pile up about 18"-2' before beginning to bury the tubing. This photo also shows how much coffee I was adding to my carbon source of neighborhood leaves. Iam not a fan of turning compost and with this type of compost water heater, forget about it. I prefer to pile in about 2-3' of leaves, wet them down, stomp them to around 4-8" and pour on the coffee grounds. Tease in the grounds by hand trying to eliminate clumps and distribute the grounds as best as possible in that layer. Slightly wet it again and repeat. Lots of potential material variation here and Iam beginning to think C:N ratios barely matter. Iam getting hot piles with leaves only and very hot piles with coffee only. I think what matters most is compaction and moisture. I thought I could lay the coil without using joints/fittings outside whatsoever. I quickly realized cutting it would work best. Of many nice things about PEX, couplings are cheap and easy. This pic also shows my "hanging spool" technique. Lucky for Brian, that pesky silver leaf maple had a tree branch right above the pile. From my roof, I rigged a pully, rope and piece of plywood turning a tough part of the job into sweet cake. 500' of 3/4" pex was my selection for the tubing and its a pretty heavy deal. Hanging the spool allowed plenty of headroom for working the layers and pulling out slack I needed between layers raising the spool up as the pile grew in height. If I didnt have a tree branch, I would probably rig up a frame or scaffolding considering the setup was so useful to the operation. Between each described layer, I would pull out 4-6 loops off the coil and create this flower shape, first securing with sod staples and later using old straw twine to tie stubborn, tighter inner layers of the spool to the fence. I tried to keep the tube about 8-12" away from the exterior of the pile.