If you’re at all plugged in to the RV community, we’re sure you’ve heard a lot about macerating toilet systems for RVs. But, how do macerating toilets work, and why would an RVer want one? In this post, we look at what a macerator toilet is and why some RVers prefer it over a standard toilet system.
What Is a Macerating Toilet?
In most RVs, a regular toilet uses gravity to flush the contents of the bowl 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 floor plans 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 spun by an electric motor. 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. So these toilets use a small amount of water for flushing liquids, but more water and greater water pressure to flush solids that the macerator has first ground up. This prevents clogs that might occur in a system 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 both pros and cons to macerating toilets.
Advantages of a Macerator Toilet
Let’s start by taking a look at the “pro” side:
- 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. Macerator 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 essential 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
With the details of what a macerating toilet is, and how it works, let’s take a look at a couple of the most popular models 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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Larry Lee
Monday 18th of August 2025
I commented on this article 3 years ago, so we are now 4.5 years living full-time in our motorhome with 2 Tecma toilets. Once I learned how to flush a time or two even after the red light occurs, it was smooth sailing--until our inverter/charger malfunctioned and destroyed both of the control modules. Replacing them was a DIY effort after receiving the new modules (not cheap). Thankfully, they failed sequentially so we always had one toilet working. I now keep a spare module on the shelf ready to install. Interestingly this would have been avoided if I had replaced the inverter/charger with the upgraded model which I had decided to do but procrastinated just a little too long! Larry
Mark
Monday 19th of August 2024
We have a Tecma macerating toilet in our rig and have been using it full-time for about eight months. It is the only toilet in the rig. The Tecma is our first experience with a macerating toilet; we’ve owned six other rigs with gravity flush toilets. The Tecma uses considerably more water for flushing liquids and solids than our gravity toilets did; 2-3 times as much water.
The 45-gallon black tank fills much faster and the 70-gallon fresh water tank empties much faster with the macerating toilet. We’ve concluded that macerating toilets are not compatible with boondocking more than a few days. Our only option to extend our boondocking time would be to replace the macerating toilet with a composting toilet. The water in the toilet bowl must be evacuated before moving the rig or it will slosh out into the floor. Macerating toilets are much less convenient to use for a quick bathroom break when traveling.
The other downside is that macerating toilets are much more complicated than their gravity flush cousins. There are electronics, sensors, a pump, valves, power wires, and buttons…all are failure points that can require expensive parts and repairs. Gravity toilets are simpler and easier to diagnose and repair, and parts are less expensive.
Clogs are also much harder to sort out with a macerating toilet. The entire pump/blade assembly has to be taken apart to unclog the toilet. It’s very important to use septic-safe toilet paper versus residential toilet paper to minimize clogs. It is critical that absolutely nothing other than waste and toilet paper is flushed down the macerating toilet. Septic-safe toilet paper has less adhesive binding the paper fibers together, so the paper breaks up much faster when wet making it easier for the blades to chop up.
Winterizing macerating toilets must be done correctly or the toilet will be damaged from freezing. The toilet manufacturer has specific instructions that must be followed precisely to minimize the chances of damage from freezing water left in the water line or pump.
Gary
Tuesday 19th of September 2023
We have a 2007 Holiday Rambler Imperial with the Tecma toilet. It intermittently will not flush. Wait a few hrs and it starts working only to have the same problem again. Light is green and tank empty. The problem is getting worse and we can’t take it out like this. Any idea how to fix this?
Thanks, Gary
Cathy
Tuesday 20th of August 2024
@Gary, Our tecma was doing this, it only got worse. Got on Amazon and, finally, found a new "controller" for the toilet. We bought one for the Marine toilet and adapted the connectors for ours. Got a happy toilet now!!
Mark
Monday 19th of August 2024
@TheRVgeeks, Our Tecma toilet has two sensors that are attached to the tank. The first sensor turns the LED on the Tecma control panel from green to yellow when the tank is between 1/3 and 2/3 full. The second sensor turns the LED red when the tank is between 2/3 and completely full. The toilet will not flush when the second sensor detects a nearly full tank until the tank is drained and flushed. The Tecma “full” sensor will lock out the toilet if the sensor is triggered for any reason. Keeping the interior of black tank flushed and clean is critical to making sure the Tecma toilet operates reliably. Unfortunately, the Tecma toilet uses the same unreliable sensors that are used to detect fluid levels in all the tanks. The sensors are adhered to the outside of the tank using double-sided tape and often fall off because they are not installed correctly during construction of the rig. If debris are allowed to accumulate on the tank interior, the sensors will trigger whether the tank is full or empty.
TheRVgeeks
Monday 25th of September 2023
Hey Gary... so sorry to hear about the trouble with your Tecma. We're pretty sure the Tecma toilets use their own sensor to determine the black tank level (basically, just a "Full" sensor, placed separately on the side of the tank). So, it's possible that there's build-up on the tank wall in the vicinity of the sensor, tricking it into thinking the tank is full, when it's empty. We'd suggest you may want to try doing a heavy-duty soaking to try and clean the tank walls and sensors (4 Ways to Clean Your RV Tank Sensors). If that doesn't do it, you COULD try searching for a black tank power washing service in your area. Or it's POSSIBLE that the Tecma's sensor is failing and needs to be replaced (though we'd pursue this as a last ditch effort).
Michael
Tuesday 5th of September 2023
Thanks for the great overview of these toilets. We like to boondock as well and are concerned about the extra water usage. We are looking to purchase a 2021 Dutch Star 4020 that has 2 of them. I know some motorhomes’ half bath is a traditional rv toilet that dumps directly into the black tank. We could then use that toilet while boondocking. However that’s not the case with this coach.
There are many factors to consider, but how many days can you stay off grid? Is the toilet the limiting factor? With our current motorhome and traditional rv toilet we can go for 2 weeks no problem. We’d like to reach that mark with the new coach as well.
I’ve read that people will flush with the water pump off and that may work some of the time, but not always! Any other thoughts from your real world experiences?
Thanks for your time and knowledge!
Michael
Tuesday 5th of September 2023
@TheRVgeeks, thanks for the quick reply. The toilets have a .8gal or .4gal flush option, so that would help a little. And the black tank is 7gal larger thank our current rig, so that would help some too.
My wife is a hard no on the composting!
TheRVgeeks
Tuesday 5th of September 2023
Hi Michael. Having two macerating toilets is definitely going to impact your length of stay in one spot while boondocking. How much it affects things will depend a bit on the difference in black tank sizes (is the tank size on the Dutch Star larger than what you have now?), how often you can not flush (i.e. #1 only) to avoid adding any more water than necessary into the black tank, and whether the macerating toilets have any option to go to a "water saving" mode to reduce the amount of water used per flush. Other than that, unfortunately there's not too much that can be done... other than removing one of the toilets and maybe going with a composting toilet? (nothing ends up in the black tank at all and it doesn't use any fresh water, either)
Werner
Monday 21st of August 2023
Hi! We have two macerating toilets in our Southwind MH and while they're convenient because there are no "pile-ups"; only slurry in the tank, one con for me was when the computer "thought" the tank was full, they wouldn't flush. First I blasted water thru the rinse port with the valve open and when that didn't work, I closed the valve & put about 10 gals of water in. Still no joy so I disconnected & drove around the park. Success for about 3 flushes. Added cleaner, water and drove to the next site & dumped. OK for 1 day. Googled the toilet & cut the sense wire & installed a momentary switch for emergency flushes. When I got home, I power-washed the tank and so far so good. The problem with having 2 macerators is no direct access to the tank.