I'm planning on moving to the Coos Bay area on the Oregon coast this summer and building a small home off the grid. A composting toilet is part of the plan. I'm a little concerned about the humidity and the quantity of rainfall we'd get on a regular basis. Would it be enough to cause issues with composting? If we built a roof over the bins would that be sufficient to protect every thing from getting too soggy? I dread mold. Does anyone have some experience with moist weather? I need some advice.
First year using Joe Jenkins method. We get 40" to 50" rain per year. My compost pile is 6' x 6' and is uncovered. More often than not the pile is partly dry and I need to add water. Jenkins has a roof above his pile and collects rainfall and controls how much he adds.
I agree with Bill that an uncovered compost pile (or bin) should be fine as long as you use a sufficient amount of straw layering on top each time the bucket is dumped. This not only provides good drainage, but it allows air into the pile to help in composting. We have historical average rainfall of +50" here (this year seems a lot higher right now) and even with that the compost bins become dry and need watering. We've been using the Joe Jenkins Humanure system for over 3 years.
One other comment because I have seen this stated incorrectly before on this forum ... Joe Jenkins does NOT have a roof over his compost bins. His system has two uncovered bins separated by an area with a roof where he stores his straw. The roof is also for rainwater collection used to clean the buckets, not necessarily to water the compost.
We made our bins using reclaimed wooden shipping pallets (approximately 4' x 4'). Try to find heavy ones that have the boards close together. These are normally used for shipping cement products and they make great walls for compost bins.
Good luck with your home building project.
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We have never had a problem with wet weather affecting our humanure composting. The bins are also used for lots of kitchen scraps and garden waste though.
if you are concerned I would simply add more carbon (sawdust) to the mix. I've never known a batch of humanure, when placed in the middle of a heap, not get hot and break down really quickly. Just try to make sure you get sawdust rather than pine shavings. We bought a bag of pine shavings once and they were hopeless - almost totally waterproof and not absorbent. It worked but wasn't satisfactory.
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We get torrential rain, sometimes for weeks on end, during the winter. I make my humanure heaps rounded on top during the winter months and when the rain gets too bad I throw a plastic sheet over the top so that the excess rain drains down the side of the heap rather than washing through the whole thing. During the summer I keep them flat to catch any bit of rain that might come along.
I designed dry/composting toilets as part of a project with small, rural landowners in eastern Ecuador. Because of the high humidity and rainfall, the design we used was to maximize airflow past the material. In wet places, urine-diversion is absolutely necessary. You can see some pictures of our design on our blog: http://bickfordsabroad.blogspot.com/2013/03/pooping-green.html
We ended up using a dessication process first (storing the material dry for 6 months). A man near where we are living has done microbiological studies and finds the local bacteria, worms, etc. die in about 4 months of holding the material dry. The extra 2 months are insurance.
After that point, we advocate a hot compost of the material. We haven't had any problems with the composting process with the piles uncovered, provided they are large enough. Rainfall where I am is over 3 meters spaced evenly throughout the year. It is rare that we go for a week without some kind of rain.
Thanks for all the ideas. We get an average of over 300 inches of rain a year in Oregon. It's literally a temperate rain forest. There's an old joke that goes around... I love the summer in Oregon, it's the most beautiful 30 minutes of the year! But joking aside, I think I have decided how to manage the rain on my compost. I'm going to build my bins withs rremovable roof. Probably just a sheet of corrugated plastic that I can clip into place when it starts pouring cats and dogs. Then when the sun comes out I can easily remove it.