How Much Do You Know About Compost Toilets?

I doubt there’s a person alive, who has thought about attempting to live off grid, that hasn’t wished they knew a few insider tricks to help that dream come true. Well, I’m going to give you a Golden Trick, … s**t rolls downhill. Speaking of that. How much do you know about compost toilets? I’m betting not much, but they could be an integral part of any off grid living plan. Let’s explore the world of compost toilets.

The very first question nearly 98/100 people ask, I was in that 98, is do composting toilets smell? The short and long answer to that question is … No. There are several reasons for this, but the two main reasons are:

  1. Compost toilets rely on aerobic microbes to break down the waste, which results in producing odorless carbon dioxide and water vapor, whereas anaerobic bacteria (septic tank) produce pungent by-products such as methane, hydrogen sulfide and ammonia.

  2. The second reason is the toilet is sealed off, and behind the seal a ventilation system which continuously pulls fresh air in from the outside air supply and vents the gases to the outside. It basically operates the same as a normal toilet, which has an integral water trap (seal) inside the commode. In other words, no air exchange takes place within the interior of the home. No smell.

What is a Compost Toilet?

With the advent of travel trailers, increased sanitary regulations imposed by government agencies, both state and federal, there was a need for a waste disposal system which would not be connected to a traditional sewer or septic tank system, yet provide safe waste disposal. They needed to avoid a mass viral outbreak. Thus, the creation of a compost toilet, which turns solid waste into compost by creating an oxygen-rich environment where aerobic bacteria breaks the waste down. These toilets are basically one of these two types of design.

Self-contained units, which houses the composting system, with the compost chamber stored beneath the bowl. This is the design you’ll find in RVs, tiny homes, boats, or seasonal homes which don’t incur a lot of use; however, some models can handle full-time residential usage.

Central (also called remote) systems, directs the solid waste, and probably liquid, to a central compost unit located away from the toilet, in the basement or, weather permitting, such as in Florida, Arizona, New Mexico, outside the house entirely.

How Does a Compost Toilet Work?

Regardless of which system you use, self-contained or central system, it is imperative you establish and maintain an environment which contains the right moisture level, carbon-nitrogen balance and temperature for aerobic bacteria to thrive, in order to enable composting of the solid waste. This environment is created by monitoring certain variables. (Before buying a unit check to see how these variables are handled by the product)

Moisture level could present a problem, as too much moisture will drown the oxygen-breathing aerobic bacteria, thus stopping the composting process. Disposal of urine is a major concern. You may ask why? To begin with solid waste is not really solid, it’s nearly 75% liquid and the gases produced by the composting process, @ 90%, will eventually turn into a liquid form. Unchecked urine disposal not only creates an over moist condition, but can also result in an excessive buildup of nitrogen. In order to maintain a proper nitrogen balance, carbon-rich materials, such as peat and coconut fiber must be periodically added.

Temperature is also important, which is why outside containment units are restricted to moderate temperature regions of the country. Consensus says a temperature range between 60 and 100 degrees Fahrenheit are optimal for providing the best composting results. Many manufacturers now incorporate thermostats, sensors and automatic mixers in order to address the temperature issue.

Some units direct the urine into a French drain or drain pit, which is essentially a hole or pit dug and filled with gravel where the urine dissipates and evaporates. Caution, if the hole or pit is not deep enough it could emit a smell. Other units are equipped with devises which evaporate the liquid waste, but a backup system, such as a container or drain pit must be still be incorporated in the event there is too much liquid to properly evaporate in a timely basis. As a very last resort, the urine can be directed to a storage container that you’ll have to manually empty.

Different Types of Compost Toilets

There are only two types, self-contained and central/remote. However, there are many different specific types of these two versions. It’s like when you buy a motor vehicle, there’s the basic model, then there’s the model with all the bells and whistles. Same for your toilet. (ever think you’d hear that?)

Dry composting toilets uses no water to operate, hence the term Water-less composting toilet, which include most toilets. Some manufacturers are sensitive to traditional prejudices and use some water to create the feel of a normal toilet flush, but usually use less than 1 pint of water to create the effect.

Electric composting toilets uses electricity to power a small fan which creates a continuous air flow through the ventilation line, and some include a heating element which helps maintain good bacteria and kills pathogens. These units are broken down into further subsets. Some plug directly into an electrical outlet, while some use rechargeable batteries to power them. For complete off the grid operation, solar operated toilets offer the option of recharging batteries or direct operation. More complex versions and operating systems offer accessories for converting the toilet to solar powered. How much do you know about composting toilets? A lot more than you did a few minutes ago.

How Much Do Compost Toilets Cost?

Now for the most important question. How much does it cost? Depends. Don’t you hate that answer. I do! But unfortunately that’s the nature of the beast. Elementally speaking a basic composting toilet starts at @ $600 for the self contained unit, while the more advanced and complex systems can run as high as $5000 to $7000, or more. Talk about sticker shock! But … the costs, although much higher than a traditional toilet, must be viewed in a broader context.

These systems are a specialty item, and anything outside the ordinary will carry a higher price tag. Call it a penalty for being different, plus supply and demand for a particular system will drive costs up. However, a traditional toilet must be hooked into a plumbing system, the water delivery system itself could cost several thousands of dollars, and that’s assuming you already have a well drilled. Drilling of a well, installation of a holding tank, electrical systems for pressurizing the system, installing water lines into and inside the house could run as high as $20,000. Installation of a septic tank and drain field will run well over $10,000. When viewed from this prospective of an expense of $30,000 or more for a traditional system, a few thousand becomes chump change.

It must be noted the water system may be required anyway if that’s the chosen water delivery system to the home. Also, keep in mind the size of family and anticipated usage will greatly effect the price of the system you’re required to install in order to handle the job.

Frequently Asked Questions & Answers

How long does it take to make the compost?

Again, it depends. The small self-contained toilets may need to be emptied every few weeks, larger central units, every few months or merely a couple of times a year based on usage. You can speed the composting process by adding accelerators, but the longer it takes to break down, the better quality compost produced.

What do I do with the compost?

That question enters the realm of personal choice. If you plan on using the compost for fertilizer, it may be best to use it around flowers, shrub, etc and not around edible plants, such as a vegetable garden. The composting process should destroy any harmful pathogens, but I wouldn’t risk it as it’s not worth the chance of becoming ill. Disposal of urine is another issue. Using urine to water grown trees is fine, but on smaller vegetation, and flowers dilute the urine with water before pouring it on them.

Can I use toilet paper for a compost toilet?

Yes. There are toilet paper products specifically made for use in RVs, etc which will easily compost, but don’t throw anything else into the toilet, cigarette butts and thick tissue are all but indestructible under these conditions.

Who can install a composting toilet?

Unless prohibited by ordnance, anyone with the needed mechanical skills can install a compost toilet. The hardest part is installing the ventilation system which will require an intake and exhaust line being installed through the wall. It’s standard procedure to place the toilet against an exterior wall for easy ventilation access, but ventilation can also be run through the roof if desire, so location is really not a problem.

I’ve completed installation, what now?

You’ll need to prime the process by introducing microbes into the tank in order to begin the composting process. I highly recommend buying their starter kit. You can use natural products, some suggest simply throwing a shovel full of dirt into the devise, but there is always the unknown involved with doing that. Although the problem of something being in the soil which creates a dangerous situation is remote, the chances of having gnats or similar critters being in the dirt is always a possibly. Why risk it?

What about gray-water?

Gray-water refers to any water that doesn’t contain biological material, such as, water from sinks, washing machines, humidifiers. This gray-water is normally disposed along with the black-water from a traditional toilet, but that sewer system no longer exists. A separate waste line must be installed and run outside to a leach field, french drain or simply out onto the ground as it is perfectly safe water for the environment. You must be conscious of a possible wet spot where the water exits, so don’t drain it too close to the house are in anticipated heavy traffic areas. Additionally, the system must be vented or else it won’t flow properly.

Why would I mess with a compost toilet?

When a traditional waste/water system is not viable. A septic system must pass a Perk-Test which means a specific amount of water must be absorbed by the ground in a specified amount of time in order to pass inspection. Should the soil fail, the normal resolution is to add more drain-field, which is very expensive. Installation of a normal septic-style tank is expensive, and considering soil content, a septic tank system may not be able to be installed, such as solid rock preventing digging. That’s not actually 100% correct. What I should have stated is the cost of using explosives or other rock piercing methods are entirely too costly.

One last tip: do not buy a compost toilet system that is too small in order to save money! The extra maintenance and attention an undersized unit will require will far exceed the extra cost in time and aggravation. The toilet is intended to stay as long as the house, why skimp?

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