[CAN] I Install A Composting Toilet in My RV? (OR NOT)

Can I Install A Composting Toilet in My RV?

Composting toilets in RVs are becoming more and more popular. They’re cleaner, cheaper to operate, and many feel they’re nicer to use than conventional RV toilets.

Composting toilets work by using micro-organisms and natural processes to decompose your feces into a humus-like substance that can be safely discarded in the same way you would dispose of any other solid waste material.

It’s basically like having a little garden plumbed into your toilet! If you’ve ever thought about installing one but weren’t sure if it was right for you or unsure about how they worked, I’m going to explain everything you need to know here.

How A RV Composting Toilet works

Basically, composting toilets take your organic waste and use aerobic bacteria to break down the solids into a more or less consistent state.

Aerobic bacteria need air in order to work properly, so composting toilets have a fan that draws air from outside the RV into the unit where it mixes with household odors inside before going back out through an exhaust vent located at the top of the toilet.

To deal with liquids, most models are plumbed directly into either the gray water tank or an additional holding tank, so you never need to empty them manually.

They have urine diversion capabilities built-in too! The mixture (mostly solid matter) is simply flushed down the drain once it’s broken down enough, which means much less waste to empty. The only residue you’re left with is some carbon-rich material that looks a lot like rich soil!

Composting toilets vary in their sophistication and complexity, but most operate on the same basic principles: solid waste goes into the toilet bowl and liquids flow down via the urine diversion system.

When you flush—using either fresh or salt water depending on your model—the waste flows out of the holding chamber by way of an outlet valve that’s closed when not in use.

Once per day (or whenever it’s convenient for you), simply open the valve, turn on the fan if necessary, and walk away while natural processes do all of the hard work for you. There are no bags to change, no chemicals to buy, and little effort on your part.

How Much Does A Composting Toilet Cost?

Budget Models vs. Expensive Units

The least expensive models are just like conventional toilets in every way except for the fact that they use a composting chamber instead of plumbing connected to an outside septic system or holding tank.

They’re really easy to install—they just drop into place as though you were replacing your regular toilet with a low-profile version—and work very well.

They don’t flush liquids directly down the drain however; instead, they must be emptied regularly (although it’s usually at a fixed interval rather than just when you feel the need).

There’s also no urine diversion capability which means that any liquid waste will end up on top of any solid waste you put into the toilet bowl. Some people don’t mind this, but it can be a little gross if you’re not used to it. It also makes cleaning the waste chamber more difficult than on models that handle liquids separately.

Composting Toilets with Urine Diversion and Automatic Flushing

If your toilet is plumbed to directly drain into your gray water tank or an additional holding tank and has urine diversion capabilities, then it’s considered to be a composting toilet specifically designed for use in RVs over conventional units.

These toilets allow liquids (urine) to flow down the drain while keeping solids suspended until they break down enough that they sink through the non-gritty substance lining your waste holding chamber to the bottom of the unit.

There, it mixes with everything else that you’ve added to it before eventually being flushed out at a set interval.

I suggest buying one of these models if your RV is big enough and has sufficient storage space for it; otherwise, a compact model could end up costing more than necessary or just taking up valuable room in an already cramped bathroom. Always measure first so you know exactly what size toilet will fit into your existing bathroom space!

Urine Diverting Composting Toilets vs. Non-Diverting Units

Composting toilets with urine diversion are much better suited to RVs because they have the capability to store liquids separately from solids until they’re flushed out (via gravity) or drained (via an automatic flush).

This means that you can install these models without having to modify your plumbing or add a holding tank, making them easier and cheaper to install.

Whether or not you should install a composting toilet mainly depends on how often you camp in one spot for more than a week or two at a time. If you’re moving from site to site all of the time, then it may be better for you to just use portable units because they’re much cheaper.

If, however, your primary form of travel is boondocking in remote regions—as opposed to staying at developed campsites—then I suggest installing a composting toilet if possible instead of hauling those giant tanks with you wherever you go!

Installing one will allow you to avoid the hassle of pit stops while allowing you to use far less water than a conventional toilet, which can save you a lot of money over time.

Composting Toilet Installation

When installing your RV’s composting toilet, be sure to follow the manufacturer’s directions for doing so since there are some differences between models that may not always be obvious at first.

For example, if yours is one with urine diversion capability, then you’ll need to connect it directly into your RV’s plumbing system (which means that it will also require electricity in order for its computer control unit to work properly).

You may wish instead to use PVC piping or other materials depending on what works best for your system and where you intend on installing it. You should always consult the manufacturer’s instructions and consider methods that best suit your own system.

Composting toilets do require electricity or they won’t work properly, but it isn’t very much power compared to what you use every day (and it draws from a 12-volt DC source instead of AC current).

If you are using solar power, then the amount of electricity used by your toilet is going to be negligible.

If you need an idea of how much power it uses, then look at a nightlight or any small appliance with a digital readout.

Many models use around 1-2 watts per hour, which will add up to about $0.78-$1.56 per year depending upon what your electric provider charges for electricity!

If you’re worried about using too much power while boondocking in remote locations, then just turn off the unit’s automatic flush and manually dump/flush the contents every four weeks or so (this should work out to once a month in most circumstances).

This can reduce its energy consumption down to one tenth of a watt per hour—which is about the same as a computer monitor.

Know that if you do choose to install a composting toilet, then it may take up to two years for its contents—depending on how often you use it and how well the system is maintained—to fully decompose into usable soil fertilizer.

Just be sure to follow the manufacturer’s directions when using yours, because improper operation of these toilets will result in their failure and can also cause health problems due to poor air quality.

Once installed correctly, a composting RV toilet can be used safely just like any other type of bathroom facility without any harmful effects from its contents or odors (assuming that everything goes according to plan).

Composting Toilet Pros and Cons


Waterless – Saves you money on toilet paper, without having to haul large quantities of water around

Odorless – Can be used in any location, even those where there is no electricity

Cheap – Once installed, it costs very little to operate, especially compared to other types of RV toilets

Dry – It’s not gross like a pit toilet when dumping, since its contents are dry (just scoop out with your shovel). There will still be some moisture depending on how humid the area is , but it’s nothing like what you might think.

Cons: Requires a working septic tank or RV holding tank with level indicator (such as a bell siphon)

You’ll need to have some type of additional waste storage system in order for the contents to properly decompose; Odorless only when it’s working correctly

If your system is not maintained according to manufacturer’s specifications, then odors will likely result; The Manufacturers Will Go Out of Business

If we all quit buying their products, then they will go out of business and this technology may never be re-invented again. I know that I won’t be able to use these forever, but composting toilets will eventually become a relic of history since most people will just use their standard RV toilet .

I would rather have my children and grandchildren know that there was once a time when we were willing to try out new technologies, so that they don’t get stuck in the same rut that we are now.

How long does it take for waist to decompose in a Composting Toilet

It depends on the type of toilet and the amount of waste that you’re sending to it. A composting toilet that is designed for a small family may only need to be emptied every few months, but larger toilets may require emptying every week.

In order to accelerate this process you can add certain natural “speed-up” factors like adding earthworms.

There are many types of composting toilets, some of which are more efficient than others. The ‘Humanure Handbook’ recommends covering your waste with a layer of dry material like straw or sawdust in order to ensure proper decomposition.

This should be done until the size of the pile is no bigger than a football. The temperature inside the compost pile will increase as you add more waste to it, so you may need to spread out the materials if this happens.

Tests have shown that as long as carbon based organic material like wood shavings and hay are added regularly, there is very little odor coming from a well maintained compost toilet.


Many RV owners may be interested in installing a composting toilet because of the water savings and odor reduction, but they are often deterred by cost.

One way to save on installation costs is to purchase an affordable DIY kit from Amazon or eBay that includes all the parts you need for installation. These kits can range from $150-500 depending on your needs and how much assembly time you’re willing to put in (some require as little as 30 minutes).

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