We hear a lot about macerating toilet systems for RVs, but how do macerating toilets work and why would an RVer want one?
Today we’re looking at the macerator toilet and why some RVers prefer a macerating unit over a standard toilet system.
What Is a Macerating Toilet?
In most RVs, a regular toilet uses gravity to flush toilet contents directly into the RV’s black tank. (For more details on how a traditional RV toilet works, see our post “RV Toilet Talk”.)
By contrast, a macerating toilet uses a macerator pump to grind & flush the waste. Because a macerator toilet uses a pump to send waste to the black tank, you can install a macerating toilet just about anywhere in an RV rather than directly over the black tank (which is where a gravity flush toilet needs to be located). In fact, some macerating toilets can send waste as far as 150 feet.
Macerator toilets work in a similar fashion to garbage disposals. They grind up the human waste and paper flushed from the toilet and then pump that waste to the black water tank. Not only does this mean that you could install a macerating toilet almost anywhere in your RV, it also means that you could even add a second toilet if you’ve got a big enough rig (and access to a route for the plumbing, water, and power needed).
In fact, macerating toilets have become more common in RVs as floorplans have evolved. Rear bath and bath-and-a-half floorplans mean that the toilet may not be located directly above the black tank, so it can’t be a gravity-drop style “traditional” RV toilet.
Traditional RV toilets have a foot pedal flush that gravity feeds toilet contents into the black tank below. Macerating toilets work differently.
Note that there’s a difference between a macerating toilet (which macerates right at the “source”, so to speak) and an RV macerator pump that connects to the RV’s sewer outlet and macerates the black tank contents to make it easier to dispose of using a smaller, longer hose.
How Does a Macerating Toilet Work?
The system that grinds up the toilet contents uses blades that are powered by a motor. That motor requires electricity to run. The blades liquefy the waste, which is then pumped through a pipe connected to the main drain line. Pipe sizing is generally ¾” to 1”.
Most macerator toilets (sometimes called upflush toilets in residential applications) have two different flush buttons. One is strictly for liquids and the other is for flushing solids.
The reason for this is that flushing solids requires more water to be used. So these toilets use a small amount of water for flushing liquids, but more water and greater water pressure to flush solids that have first been ground up by the macerator. This prevents any clogs that might happen in a system that’s moving solid contents through a discharge pipe and plumbing system.
What Are the Pros and Cons of Macerating Toilets?
As with anything else, there are pros and cons to macerating toilets. Let’s start by taking a look at the “pro” side of the pros and cons.
Advantages of a Macerator Toilet
Flexible Installation Location
Installing a macerator toilet offers flexibility with an RV’s floorplan because it doesn’t need to be located directly above the black tank. They’re also relatively easy to install.
Lack of Odor
A macerating toilet system blocks direct airflow from the black tank when you flush. For this reason, you’re very unlikely to ever get an odor from this type of system.
More Traditional Throne
The actual toilet involved in a macerating toilet setup generally tends to be more like a traditional toilet in terms of form, function, and experience.
The toilets tend to have porcelain bowls with elongated seats, and flushing usually involves pressing a button as opposed to a foot pedal and spray wand as is often found in RV toilets.
Clog Prevention
Because waste is liquified before ending up in the black tank, you’re not likely to get clogs when dumping. Preventing a plugged black tank is also important for the proper functioning of RV holding tank sensors.
RV tank sensors can get gummed up by paper and solid waste over time. A macerating toilet grinds up solids before they hit the black tank so may be less likely to contribute to tank sensor issues.
Disadvantages of a Macerating Toilet
Now let’s take a good look at the “cons” of having a macerator toilet in your RV.
Higher Water Consumption
A macerating toilet generally uses more water and can deplete your RV fresh water tank faster, while filling your RV black water tank faster, too. If you tend to do a lot of long-term boondocking (like we do), this is an important consideration.
More Moving Parts Involved
Because a macerating toilet has a motor and many moving parts, there are more things that can go wrong, and more parts prone to failure.
Requires Electricity
The fact that these toilets require electricity not only means that you’ve got another “appliance” to power, but it also means that if your RV loses power or your batteries die, you can’t flush your toilet.
More Expensive
Macerating toilets are more expensive to buy and replace than their traditional gravity flush counterparts.
Toilet Sensor Can Prevent Flushing
Most macerating toilets have a sensor (or are tied into the existing black tank level sensor) in order to disable the toilet when the tank levels are too high. This is important to prevent overflow, but it also means that you can end up in a situation where the toilet won’t flush. There are workarounds for this, but it can still present an issue.
Popular Macerating RV Toilets
Now let’s take a look at a couple of the most popular macerator toilets for RVs.
Thetford Tecma Silence Plus
The Thetford Tecma is a wall-mounted unit that weighs just under 69 pounds. It uses a virtually noiseless turbine pump and is self-contained (meaning that it requires no external/separate pump or macerator).
The Tecma flushes with the push of a button and has a sensor that indicates when your black tank is empty, half-full, and full. The toilet itself is made of a solid porcelain base and has a molded plastic seat and cover.
Dometic Masterflush 8740
The Dometic Masterflush has a flushing process that’s quieter and shorter than most other macerator toilets. To help with water usage, it also offers two levels of flush (normal or low). It’s a residential-style toilet of standard size and height and has an elongated bowl.
Discharge fittings can run through the floor or through the wall, and flushing occurs with the push of a button.
The Dometic Masterflush weighs only 41 ½ pounds.
If you’re interested in learning more about how a traditional RV toilet works for the sake of comparison, feel free to have a look at our YouTube video on the topic.
Do You Have a Macerating Toilet in Your RV?
If you use a macerator toilet in your RV, we’d love to hear about your experience. Drop us a comment down below!
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Marc Goldstone
Wednesday 12th of October 2022
Rather than changing out the toilet I use a hybrid approach to getting rid of PooPyramids even while Boondocking without wasting any fresh water.
I had a year ago added a standard Dump valve attached Macerator along with a 3" 'Y' adapter and 2 additional gate flush valves, this so that I can dump quickly at dump stations with a "Stinky Slinky" hose as well as using the Macerator while parked at home where I need to pump the waste a couple of feet uphill to the septic port.
A couple of weeks ago I made an additional modification with two 1" PVC ball valves so I can direct the Macerator's output either to a garden hose and the septic system OR back into the black tank just upstreeam of the toilet's down pipe where poopyramids form. By running the Macerator for a couple of minutes in the later configuration the poopyramids are pushed toward the Macerator and the contents of the black tank is pulverized without wasting any extra fresh water which would fill the black tank, prematurely ending our Boondocking outing to dump waste and refill the fresh water tank.
I used a 3/4" Uniseal and MrStickys 2-part adhesive for added reliability mounted through the bottom of the black tank with a PVC pipe inserted through the Uniseal fitting that directs the Macerated effluent horizontally toward the toilet downpipe. No leaks, no water waste, and no more poopyramid backups in the black tank.
If the RVgeeks are interested in the specifics of this modification I can provide some photos...
Doug LaFeve
Sunday 28th of August 2022
Hey guys, love your channel and appreciate all the great information you provide. Have watched since 2017 when we first bought our 42’7” 2009 Monaco Knight. Your videos taught me how to drive the beast. We have a Tecma macerating unit as well as a separate macerating pump. We are on our second pump unit which is a turbo model which works very well to pump out the tanks. We do not boondock as we winter in AZ and summer work camp at a resort in McCall Idaho. Water usage is not a problem and we do tend to use a lot of black water. On average we have to dump every 3 to 4 days. That is sometimes inconvenient as you might guess.
Our rig also uses the sanicon system which allows you to back flush grey water into the black tank to help flush the tank. Our tanks are side by side (one bathroom) and the bottoms are level with each other. The grey is 60 gal and the black 40 gal. It works well with the macerating system but not as well as with standard dump lines. The turbo macerator allows more fluid to flow past through the pump bypass when a line is open than the old system did.. I also use the water tank flush line to rinse as well.
The major problem that I have with the macerator pump is that you always have fluid in the tank 3” feed hose from the tank outlets to the pump. This is a nuisance if you need to switch to standard sewer hoses. The other problem I have found is that when I have switched to standard hoses (due to macerator failure or blockage) the clear fitting tabs break EVERY time you try to remove it from the tank discharge. Which has resulted in having to replace that piece of plastic multiple times. I now keep a spare one on hand. (They are not inexpensive to replace.)
Overall the system works great in our 13 year old coach. We are full timers since 2018.
Stay safe and keep up the good work. Hope to meet you someday while on the road.
Doug LaFeve
J. Koenig
Monday 22nd of August 2022
My 2015 Dynamax DX3-37RB had TWO Tecma macerating toilets as OEM gear. They've generally been problem free. Several years ago, I attended an RV Rally where Gary Bunzer (aka The RV Doctor) was presenting a seminar. When I asked Gary about macerator systems his response was that he LIKED macerating toilets but did NOT favor whole rig maceration systems. Sadly, Gary was an early covid fatality. He was a true gentleman with an incredible wealth of knowledge about RVs that he shared with anyone who asked.
TheRVgeeks
Monday 22nd of August 2022
Gary was, indeed, a true gentlemen and extremely helpful. He will be dearly missed!
Bruce
Monday 22nd of August 2022
We have a Dometic macerating toilet in our rear bathroom. Boondocking with a mascerating toilet is a real challenge because of the water consumption. There is a setting that allows you to reduce the water consumption, but even then, the regular toilet in our front toilet is a better option. We have found that when we have full hookups, the water consumption for the mascerating toilet increases the frequency with which we have to dump our black tanks.
Even though the mascerating toilet has a sensor to monitor tank levels and stop you flushing, ours has a light in the button panel that turns orange when the black tank is at 66% and red when it’s full. We’ve found that to be a relatively useful reminder to flush the black tank. When the orange light goes on, it’s a reminder to close the gray tank before we dump the black tank.
The positives are spot on and we really like having it, but the cons mean there are times where we don’t use it.
Greg
Monday 22nd of August 2022
I have a new Thor Hurricane. It has a mascerator pump integrated with the drain pipes and mashes and recirculates the tank material. It is not connected to the toilet. The vehicle manual did not cover how to use it so I had to figure out how to use it. The tank has to be 20% full before using the mascerator. And it is important to activate the mascerator each time the toilet is used via a switch on the wall after the 20% is reached. Otherwise a pile up occurs which is not good I found out!
Marc Goldstone
Wednesday 12th of October 2022
@Greg,
I had no idea that one of the RV manufacturers had a recirculation system. Mine didn't so I implemented a similar approch. I submitted my implementation to this Blog. I need to enable my drain pipe macerator with a switch located in the WET BAY as well as making sure there is some water in the black tank which is always the case after a few days of boondocking..
Marc
TheRVgeeks
Monday 22nd of August 2022
Sounds like what you've got, Greg, is an RV macerator pump like we discussed in our article on the topic: What Is an RV Macerator Pump? And Do You Need One?