More Stuff That Works – RV Black Water Macerator Pump

An RV black water macerator pump is not something you use while staying at a typical full service campsite. This device IS beyond handy while parking in places like the driveway of friends and relatives without RV hookups. At our current stop, we are parked in a horse corral behind a bunkhouse. The macerator works by sucking the black water yuck out through a macerator that resembles a garbage disposal in a sink. By first macerating the yuck, you get a uniform stinky liquid that can easily go into any toilet, sink or other direct connection to the sewer system. Warning, it will stink until the brown water is gone. We are dumping into the toilet of the bunkhouse. It stinks until we’re done and the toilet is flushed. Since we are also showering in the bunkhouse, we only need to empty the black water once a week. We are using our trailer to work and cook in while we stay, so this means we can also use the bathroom in the trailer without worrying about how to dump. We have also used the macerator while boon docking to dump before pulling out. (Always check first, especially in the north, to make sure you are not dumping your raw sewage into a rainwater disposal.)


The macerator itself fits into a nice little black box in which I also keep a dedicated needle nose plier, a spare fuse, and a container of sanitizing gel. I also recommend having two sets of spare impeller parts. The impeller has a bad habit of failing without warning and this is one job you don’t want to be stuck waiting for spare parts for. One spare part is seen with the macerator box. I have had to replace the impeller twice in five years. Spare parts are available only when ordered on line. Replacing it is actually relatively easy as long as you make note of how you took it apart so that you can put it back together the same way.


Standard RV sewer outlet. We arrived in heavy rain and trailer sunk. Normally it’s not that low to the ground. We are using the $39 sewer cap add on since I toasted our grey water valve by trying to force it while frozen last year in Washington state. We were quoted $400 for replacing the grey water valve so we decided to just add this thing on instead. I recommend this addition as one of one’s must have spare parts, just in case you are ever left with damaged valves and need to move without dripping all over the highway.





The macerator is hooked up with fresh water intake on one side a standard hose. The fresh water intake has its own flow control valve (green in this picture). The output side connects to a standard garden hose. The manufacturers recommends no more than 50ft of hose but we have found it works just fine with 100 ft. We hook up to the batteries in the front box. The handle control has a fuse in it so if you hook it up backwards the fuse burns out instead of the device. Idiot proof. I keep a box of spare fuses and one in the macerator box because of my own idiot moments.


The procedure is open the black water and grey water valves first and let the grey water back flush into the black water side. This prevents clogging and makes sure there is enough liquid for the macerator to macerate the solids. After a couple of minutes, when the glugging mix noise stops, start the motor. The mixture is sucked out. The pump noise changes when it has no water. The pump requires flowing water to stay cool so you need to shut it off as soon as the yuck is pumped out to avoid burning out the motor. Close the black water valve and then open fresh water intake valve to backfill the grey water side with fresh water. Run the pump to clean. Close the grey water valve. The repeat the flush for macerator. If you let the fresh water intake run through the pump until the hose is thoroughly flushed as well, life is much more pleasant at disconnect time. (If I am camping at a place without a fresh water connection I will take a shower with the plug in tub and after pumping out the black water, close the black water valve, and pull the plug using the shower water in the tub for the flush.)


As you can see from this photo, if properly flushed using the fresh water intake valve, you are not stuck with anything too yucky when you take the macerator off. However there is always some hair that needs to be removed. This is what the dedicated needle nose pliers are for. (The pliers are handy for changing the fuse when I am idiot too.) Repacking all the wiring is the hardest part. Elapsed time is typically 20 minutes from start to finish.


About tumbleweedstumbling

I have three blogs, embryogenesis explained, tumbleweed tumbling AND fulltimetumbleweed. I am a scientist, and my husband and I have written a book which was published by World Scientific Publishing in Nov 2016 called Embryogensis Explained. Full time tumbleweed was my first blog which I worked on during five years of living full time in a travel trailer. I have now retired that blog in favour of Tumbleweeds Tumbling since we bought a stick house in April 2015 and are no longer full-time. I have a blended family of five sons and one daughter, all grown up now. I am (step)grandmother to nine boys and one girl. My husband and I have a dog and a cat. We spend summers in Manitoba, Canada, in a 480 square foot house on a half acre of land in the tiny town of Alonsa. We spend winters in the USA. My husband is retired and being a US citizen, he does volunteer work in winters for Gulf Specimen Marine Lab in Panacea Florida as their emeritus. I retired in Sept 2013 and so far I am loving it.
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