How About a Composting Toilet?

I've been thinking about purchasing a composting toilet such as this one from Nature's Head.

Why a Composting Toilet?  

I've been thinking of various living scenarios we'll encounter over the next few years:

Our current off grid house:  Our standard toilet here in the high desert of New Mexico uses water to flush waste.  This water is gathered from a rain water catchment system on our roof.  We have long periods without any water coming from the sky; water is very limited and we conserve any way we can.  We flush as little as possible in order to save water.  Flushing the toilet also uses significant electricity since re-filling the toilet water reserve tank requires the use of the electric pump to draw water from the  outside cistern into the indoor pressure tank that feeds the water to our toilet.  Our electricity comes from our solar panels and is stored in our house batteries.  To avoid draining down the house batteries, we again avoid flushing unless necessary, particularly at times when the batteries at their lowest such as at night, on cloudy days, or in winter when days are short.  Additionally, this particular toilet frequently doesn't flush completely and requires a second flush.  The toilet drains to a septic system that must be periodically emptied, so our landlord has requested that we dispose of used toilet paper in the trash rather than the toilet.  As you might imagine, infrequent flushing and toilet paper gathered in an adjacent trash generates a fair amount of stink.   This is my least favorite part of living off the grid.  

We do have an outhouse as a backup.  I'm not opposed to outhouses and managed appropriately, they don't stink.  I even occasionally enjoy using the outhouse.  There's something peaceful about doing your business with the outhouse door hanging wide open so that you can stare out at the desert and the sky.  

Outhouse

But I don't want to trek out to the outhouse several times each night, and I especially don't want to make the walk in the winter when there's a strong, cold wind blowing or snow and ice on the ground.  I did this during my off-grid childhood and I'd rather not have to do it now.   

Brr. Outhouse in the snow.

A composting toilet avoids the disadvantages of both the flush toilet and the outhouse.  It uses no water.  It uses minimal electricity.  It doesn't stink.  And it can be kept inside.  Plus, it converts what would otherwise be a waste product (that we would have to pay to dispose of) into a usable resource: compost. Thus, it's a great solution to our current problems. 

RV:  

In the last few years, we lived full time in our rv.  It's likely that we'll live either part or full-time in it again in the next year, while we travel.  When we stay in the rv, we want to have the ability to boon dock (camp in non-developed places without water, sewer or electric hookups such as BLM land) or stay in parks that don't have sites with full hook-ups.

Our current toilet rv toilet uses water to flush, requires electricity to operate the pump that supplies water to the toilet, and flushes waste into the black tank.  When we're boon docking, our water supply is limited to what’s stored in our freshwater tank.  Our electricity is limited to what’s generated by the solar panels and stored in the batteries. Our toilet waste water storage feeds into a black tank which, when filled, must be emptied, either into another portable tank which must then taken to a dump, or by moving the entire rv to a place that has a dump.  It’s inconvenient to move the entire rv every time we need to dump the black water or to pump out the tank.  Plus it's a disgustingly stinky process with potential for foul spills.

The advantages to a composting toilet in the rv are the same as those that accrue in our off-grid house.  In the case of the rv, it has the added advantage of not requiring us to hook up our trailer to the truck and move the combination to where the waste can be disposed of.

Future land:  

Another living scenario for our near future is buying a piece of land, living there for periods of time, and then moving to warmer climates during the cold and snowy parts of the year.  This land will likely not have power, septic, or a well, though over time we may choose to have them installed, especially if we build a cabin or other form of permanent housing.  We would be living in the rv or a small temporary building.  In any case, prior to installing these systems, we would need some kind of toilet system that uses minimal water and electricity, and doesn’t require a septic system.   

Future housing:  

Another living scenario includes moving into an on-grid house.  In that case, why would a composting toilet be useful?  The last two on-grid houses where I’ve lived have lost power for periods of up to a week from various kinds of intense weather including a hurricane, strong thunderstorms, and snow storms.  We resorted to using local store restrooms (happily not far away and open when needed) and pee buckets.

If we move into another off-grid house, a composting toilet would have the advantages I've already mentioned.  Additionally, in the last off grid house we lived in, the drainage pipes for the sink and tub froze.  The pump in the pump house also froze, cutting off our water supply and we had to find a way to keep the pump house temperature above freezing (we used a candle).  Thankfully, the septic pipes did not freeze.  In that same house, the septic tank filled up and needed emptying in the winter, when the tank was under three feet of snow.  We had to get someone to come in with a plow and a front loader to access the pump out area.  In the meantime, no flushing.  Any off-grid house we might live in in the future would be subject to the same risks.  Pooping outside in the snow, especially when the wind is blowing, the snow is deep, and the ground is frozen isn't a great thing.

So, Then, A Composting Toilet

There are cheap ways to construct a portable composting toilet.  Some people simply put a toilet seat on top of a five gallon bucket and fill the bucket with sawdust or some other absorbent material like  coconut coir.  If you pee in one bucket and poop in another it will minimize odors.  People using this system then bag or dump the waste into the trash, put it down an outhouse, or compost it.  

A more sophisticated (and of course more expensive) solution is a composting toilet that closely resembles a standard American flush toilet, such as the one pictured at the top of this post.   This toilet by design separates the liquid and solid wastes into two different receptacles.  Reviewers say the solid waste doesn't stink and the tank holds about a week's worth of material before it needs dumping.  The urine tank needs to be dumped every day or two.  I've read that putting a few tablespoons of sugar in this tank before each filling will minimize the odor while dumping.

Dumping

Where can the contents of the tanks be dumped?  This topic is controversial and it's difficult to find a standard, verifiable response.  I'll leave this for a separate post.