Composting Toilet — Report on 8 months full time usage

[JRhetts]

I guess its time for a report on our use of the NaturesHead composting toilet.

As a part of our remodel of our Darrin Fink-built FusoFM260-based expedition vehicle, we elected to install a composting toilet in lieu of the Thetford cassette. We have been living in the rig full-time for 8 months.

We primarily wanted

• longer between-dump times,
• less water usage, and
• more flexibility in dump strategies,
• without incurring any increased 'messiness' in the process.

OVERALL EVALUATION: BINGO!!! This has been a winner!

The unit is very well made, simple to install, and the company provides excellent customer service.

As a baseline with the Thetford cassette, two of us living aboard full-time had to dump every other day. And despite the fact that we both preferred to dump a cassette rather than deal with a hose and a big blackwater tank, with a cassette it is still a smelly and at least mildly messy business.

NOTE: With this kind of composting toilet the physical apparatus separates urine and feces. So you have two separate vessels to empty. While this may sound like more work, we DEFINITELY found IT IS NOT. The nasty smell comes from combining the two; neither alone is particularly bad [ esp. not the feces.]

With the composting unit, in warm weather we got up to one month between dumpings of solids, and in cold weather [averaging low 40s to low 20s °F] it averaged 10-14 days between dumps of solids. The liquid bottle had to be dumped regularly every other day, but this was MUCH easier than the same frequency with the cassette combined output. Simply put, we could dump sterile pee lots more places with less splashing and odor than the combined output from the cassette. The solids are remarkably easily dumped into an ordinary plastic 13 gal garbage bag, and then either spread around as fertilizer or placed for landfill collection. And since the solids are not in liquid form, there is NO SPLASHING or other objectionable side-effects from doing the dumping.

Interior smell from the toilet was virtually non-existent until we had reached the limit of the peat moss volume, and then it was more like a gentle nudge to "do the job."

We used a small spray bottle with water to "assist" the last of one's pee to fully vacate the front part of the bowl, so water usage was less than one liter per dump — i.e., VERY low.

We find this an optimal way to deal with the inevitable problem, and are very glad we went this direction.

SO, after 8 months of full-time 'living', these are our observations.

John

 

[Roaming Robertsons]

Thanks for the info. This seems to be a curiosity out there but without much good info. You mention the solids and liquids having separate compartments. What happens with the toilet paper? Does it go down with the solids or is it handled separately?

 

[dwh]

What nobody ever mentions when talking about these portable composting toilets, is that if you take a crap in it on Tuesday, and then empty the solids container on Wednesday - what you are emptying is NOT compost...it's feces.

It CANNOT be spread as fertilizer because it has not had the time (or temperature) for the composting process to destroy the bacteria and pathogens.

Composting takes time. If there is also temperature, then the time can be reduced, but even with temperature, it's not a fast process. That's my problem with these portable composting toilets - I can see using one for a few months, and then letting it sit for a few months for the composting process to run its course, then emptying it. But empty it too soon after using it, and what you are disposing of is NOT safely composted human waste:

http://weblife.org/humanure/chapter7_19.html



I'm also pretty sure it's not legal to just toss it in a handy dumpster either. Most states allow the solids from a composting toilet to be thrown away only if A) it's actually compost, and B) the trash is destined for a "sanitary landfill":

http://weblife.org/humanure/appendix3.html

http://web.mit.edu/urbanupgrading/urbanenvironment/sectors/solid-waste-landfills.html


Uncomposted (or partially composted) human waste is sewage and so the normal sewage rules apply.

 

[JRhetts]

Thanks for the info. ...What happens with the toilet paper? Does it go down with the solids or is it handled separately?

You can add paper to the solids as you do with a flush toilet; this slows down the total time for composting. We use a separate small wastebasket, as is the custom in Central and South America and much of Africa; smell is negligible between empties.

 

[Cat Jockey]

Thanks for taking the time to fill us in. That helps push me to take the jump I have been considering.

Concerningdhw's concerns, there are solutions to this. What I have decided that in combination to a composting toilet I will bring a rafting expedition grade toilet system as well. You can get these in sizes of a 5.5 gallon cassette down to a size that will fit inside of the bow or stern of a kayak. Dumping on Weds? No problem. Use your groover monday and tuesday (or how ever many days prior needed), properly dispose of the composted material on weds.

As far as what to do with your now used groover, well, I am sure one could add the contents to the composting toilet, but you don't have to. A groover can be stored outside the vehicle, emits no smell if you store it in your toilet area, utilizes RV dumps. Keep in mind too that us rafters can go out on the river for 3+ weeks, sitting next to a FULL groover (I am talking 5.5 gallons of number 2 in a 20 mm ammo can) baking in the desert sun. And depending upon the length of trip, a rafter could find himself surround by 4 full groovers. 20 gallons of good stuff.

Properly treated and NO #1 with the #2 and it is no big deal to let a groover sit for three weeks with stuff in it, even on the roof of your rig in direct sunlight.

Maybe it sounds like a hassle to have two toilet systems, but to me, it is a lot less hassle then having a blackwater system including tank, antifreezing measures, weight, space, dependency on RV dumps.

More importantly, the compost/rafting groover combination gives me MORE freedom to be further away from more people for a longer period of time. Even if I did a cassette, I would still bring a rafting groover so that in addition to an outside shower, I can have an outside bathroom for nice weather - let's face it there is something to don't @$!% where you sleep and eat and any time I can utilize an awning or pup tent for an outside bathroom while camped, I will, regardless of what the internal toilet system is and how comfy the seat may be.

Thanks for the report and just my $0.02 to make the composting toilet a completely valid, no need for rv dumps, system.

 

[Scott Brady]

John,

Thank you for the detailed review and your experiences. As with the diesel cooktops, there was a lot of missinformation floating about.

All the best in your travels.

 

[dwh]

Dumping on Weds? No problem. Use your groover monday and tuesday (or how ever many days prior needed), properly dispose of the composted material on weds.

Yea, not a bad idea. The problem is time. With heat to kill the bacteria and pathogens, you could make it safe in a matter of minutes. It still wouldn't be compost, but at least it would no longer be hazardous waste.

Without heat, the recommended time to let it sit is a year. A Year.

Don't get me wrong, I really LIKE the composting toilet idea, and I was looking very hard at replacing the Thetford and 10g black tank in my camper...but I just can't get around the problem of what comes out of a portable composting toilet is neither compost, nor decontaminated.

Which means that while it would surely be handy, it still has to be treated as sewage and dumped into a proper sewage disposal, just like a cassette.


Also, forgive me if I seemed to be coming down on you John - I certainly wasn't and I too very much appreciate the time and the report. I really want one of these myself...but...this one issue keeps nagging at me.

 

[The Adam Blaster]

Without heat, the recommended time to let it sit is a year. A Year.

Just curious on this point - what do you mean by "without heat"?
Are you saying at the point of freezing, absolute zero, somewhere in between?
A year seems an excessively long period of time to compost some semi-solid materials, especially when a generous amount of peat has been added to the mix.

 

[kerry]

Anyone have a link to the composting toilet in question?
About 15 yrs ago, most western rivers imposed the requirement of having a washable toilet system on raft, canoe and kayak trips so the waste could be dumped into RV waste stations. The BLM claimed that it was necessary because boaters were dumping garbage bags with human waste into local landfills and this was not permitted. Seemed like an odd claim to me so I called the EPA or whatever federal agency was responsible for landfills in the west. I was told that the BLM was giving us a line of BS. As I had thought, the person at the federal agency pointed out that if this was the case, why were diapers allowed in landfills? Plus sewage sludge from wastewater treatment plants was routinely dumped in landfills.
Given that phone call, it's hard for me to imagine that dumping the output of a composting toilet into a landfill would be a problem.

 

[Hill Bill E.]

Anyone have a link to the composting toilet in question?

Not sure which model they have, but here is the site: http://www.natureshead.net/

John, does your toilet require power?

Back a few years, I looked into these for my cabin, but the ones available required either power (12V or 110V) or an extensive vent system.

I know they have gotten better over the years, just curious if yours is powered, or has a solar powered vent fan.

 

[bajajoaquin]

Just curious on this point - what do you mean by "without heat"?
Are you saying at the point of freezing, absolute zero, somewhere in between?
A year seems an excessively long period of time to compost some semi-solid materials, especially when a generous amount of peat has been added to the mix.

I'd guess that "heat" means something over 100 degrees Fahrenheit for a sustained period. This is to allow the bacteria to break down the pathogens and make feces into compost.

It seems to me, from DWH, Cat Jockey, and the original poster, that the value here is not that you create compost, or that you decontaminate the waste in a reasonable amount of time. The value is that by separating the waste into solid and liquid, you can extend the effective capacity of your holding tanks. Each, on its own, is easier to dispose of than when you mix the two.

 

[dzzz]

All existing mobile toliet systems have potential exposure to pathogens, so I don't see how the lack of complete composting is a problem. It's not like anyone is having a snack while pumping out a black tank or emptying a cassette into an outhouse. Low odor pooh once a month into a garbage bag sounds pretty good. No water in the bowl and special TP processing not so good.

But overall the report sounds very good. Especially based on full time use. What's an alternative to Natures Head that has a liftable seat? I understand why the Natures Head seat design might be desirable, but I ain't peein' sitting down.
Natures Head says the fan uses 24 amp/day. That's non-trivial for some smaller electrical systems.

 

[kerry]

On the river in canoes we always burn our toilet paper in a coffee can to reduce volume in the toilet. A little ingenuity might integrate a tiny incinerator into the composting toilet to burn the toilet paper and provide some heat to speed up the composting.

 

[Cat Jockey]

Definitely valid points dwh. Even if you adhere to treating 3-4 week old compost as contaminated, there is still a huge difference in mobility and freedom and length of stops at RV dumps:

As a baseline with the Thetford cassette, two of us living aboard full-time had to dump every other day.

&

With the composting unit, in warm weather we got up to one month between dumpings of solids, and in cold weather [averaging low 40s to low 20s °F] it averaged 10-14 days between dumps of solids.

Huge difference for those like me that do not want a black water system. If you live in your rig for a year, you are talking about 20 RV dumps versus 180 - eliminating almost 90% of neccessary stops with a cassette. It means the freedom to camp in the middle of nowhere for a month versus 2 days.

 

[Cat Jockey]

Anyone have a link to the composting toilet in question?

http://www.airheadtoilet.com/
http://www.natureshead.net/marine.html

I like this one:

http://www.sun-mar.com/prod_self_mobi.html

A little ingenuity might integrate a tiny incinerator into the composting toilet to burn the toilet paper and provide some heat to speed up the composting

They make those too:

http://ecojohn.com/ecojohn_sr.html

I am planning a collapsible propane incinerator. I have experience working a homemade propane bronze foundry and have been working on a design for a small RV unit. That takes care of a lot of trash issues as well and can make you completely independent of RV dumps by incinerating the composting toilet contents and providing 1000 miles of fuel, well, you can disappear for a while without needing anything.

Land sailing daddy-o - completely self supportive for extended periods.

The BLM claimed that it was necessary because boaters were dumping garbage bags with human waste into local landfills and this was not permitted.

That was a problem. A lot of these rivers out west are in the middle of nowhere. You get off the river and the closet town could be a 45 minute drive and at that point, the town could be a gas station, general store and a post office. You get rafters, everyday getting off of the river with 12 people after a week and they throw their crap in the gas station dumpster. We are not talking metropolitan sized landfills where it wouldn't be noticeable.

The other influence was the increasing volume of users escalating after the 80's. There are a very limited number of campsites on the river (only certain places where you can actually get the boats eddied out and have an area to make camp), so each camp site has high usage. Cat holes and toilet paper and open pile 'o poo became a problem. Add to that the most of these rivers go through desert or semi-arid enviornments and you have a problem. As an example, one stretch of river in Colorado recieved 250,000 visitors, mostly commercial rafters, in a 3 month period at the industry peak. Most confined to a 10 mile stretch with a dozen places to stop. That is a lot of people using a very, very few stops, to eat and camp and use the bathroom.