What’s the best way to clean RV holding tanks? Photo credit: Shutterstock
What’s The Easiest Way To Clean RV Holding Tanks?
Cleaning your holding tanks is one of those RV maintenance chores that needs to be done on a regular basis. If you don’t keep them clean, RV black and gray tanks can start to smell really nasty. In addition, if you don’t keep your tanks free of buildup, your tank sensors will get covered with crud and they won’t function properly.
You can’t get around having to clean your holding tanks at least once a month when they are in use. A quick Google search reveals many methods for getting RV holding tanks clean. However, we wanted to find the most effortless, simple method that anyone can use for cleaning their RV holding tanks.
What you need to know about RV holding tanks
Here are a few things that will help you keep your gray water and black water tanks clean and performing at their best. In general, you want to keep things from drying out to avoid buildup on the bottom of your holding tanks. With this in mind:
- Always keep at least 5 gallons of water in your holding tanks to prevent buildup from happening and keep them from drying out. If you have water in your holding tanks when you are traveling, it will swish around, helping to clean any gunk off the sides of the tanks. Also, dumping a bag of ice into your black tank before you travel will help clean it as you drive.
- Always keep gray and black tank gate valves closed until they are more than half full. Even when you are hooked up to sewer services, you’ll avoid drying out your tanks by keeping RV valves closed. Allowing your tanks to fill halfway before emptying them helps to ensure that there is enough weight in the tanks to push everything out when its time to empty them.
- You should only flush digested materials and RV-safe toilet paper down your RV toilet. This will ensure that you avoid blockages in your RV’s plumbing system.
- Harsh chemicals and bleach will damage RV holding tanks and their seals. Never use bleach, Draino, or any harsh chemicals in your RV plumbing system.
Use an overnight RV holding tank treatment
The easiest way to clean RV holding tanks is by letting an enzyme-powered holding tank cleaner work overnight in your tanks. Here are a few of many enzymatic tank cleaning products that promise effortless overnight cleaning.
- Super Seal Pirranha is an enzymatic liquid product that is designed to break down and liquefy anything in your RV’s black and/or gray tanks.
- Thetford Tank Blaster comes in drop-in pouches that use microfoam to help loosen crud inside your holding tanks. Thetford’s customers agree that Tank Blaster gets rid of crud in RV holding tanks when used as directed.
- Walex CMDOBG Commando Black Holding Tank Cleaner comes in pouches designed specifically for cleaning blackwater holding tanks overnight.
No matter which holding tank treatment you choose, there are some steps you’ll need to take to get it to perform properly. Enzymatic cleaners contain enzymes that happily eat and digest the stuff on the inside of your tanks. But you’ll get better results if you make their job easier. Here’s what you need to do:
- Use the treatment while you are hooked up to sewer services. This will allow you to fill your tanks up before you empty them.
- Fill each of your holding tanks to more than 75% of their capacity. Having them as full as possible will really help get them clean.
- Empty your black tank and then your gray tank. The soapy water from your gray tank will help clean any remnants in your sewer hose.
- Now flush your black tank with either your RV’s black tank flush or a tank flusher like this one from Valterra.
- Before you go to bed, mix or dissolve the manufacturer’s suggested dose of tank treatment into a bucket of warm water and dump this down the toilet. If you are treating your gray tank, mix up a second bucket to carefully dump down whichever drain is closest to the gray tank. This is often (but not always) the shower drain.
- Now fill up your holding tanks with water.
- In the morning, repeat Steps 1-5.
- Test your black tank’s cleanliness by turning on the overhead fan and opening the valve in your toilet. There should now be no offensive odor.
Track your RV maintenance
Make sure you keep track of all your RV maintenance and repairs with an online tool such as RV LIFE Maintenance. Not only can you keep all of your documents in one place, but you’ll also receive timely reminders when maintenance is due to help you avoid costly repairs and potentially serious accidents.
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Lynne lives, travels, and works full-time in a Forest-River R-Pod 180 with her 2-pointers, Jolene and Annabelle. Lynne has been an enthusiastic RVer for over 35 years. And then one day in 2019, she began full-time RVing as a lifestyle experiment. She quickly fell in love with the convenience, freedom and minimalist lifestyle offered by full-time RV living. Lynne is a professional writer and has been a professional dog trainer since 1995. You can read about her travel adventures on her R-Pod Adventure blog, R-podyssey at: http://www.rpodaventure.com
Great clear concise article. Thank you and keep them coming.
Good article for newbies, except for putting ice into the tanks. Unless it’s below freezing outside, the ice will melt be for you even leave the park.
Putting ice in the tank can also tear up the sensors inside your tank resulting in poor or no readings.
If you have a washing machine inside your motorhome, there is a warning on the front of the washer to “Be sure to open the gray tank valve BEFORE operating the washer”. Failure to do so may result in overflowing the gray tank.
My trailer is plumbed for a washer. The drain line runs directly to the main drain, Keystone wants the waste from the washer to go directly out.
After we dump our holding tanks…I put a 4 gallon pail of hot soapy water into both tanks then rock the trailer back and forth then empty them into the dumping station.
Then I put some Downey fabric softener into both tanks…and that keeps them odour neutral till we dump again!
Good advice
I’m full time hooked up to city services. I dump my black & gray tanks weekly. I’ve been using the Walex Porta-Pak Lavender packets. They keep things flowing nicely & smelling lovely. 😍
I use both kinds of paper depending on my budget at the time. I like the softness of the Scott RV paper but the Aldi single ply is sooo budget friendly.
Easiest way is to put 4 gallons of water in your black tank and a packet of chemical and drive down the road.
This is very concise
Instruction on RV maintenance
“3. Empty your black tank and then your gray tank. The soapy water from your gray tank will help clean any remnants in your sewer hose.
4. Now flush your black tank with either your RV’s black tank flush or a tank flusher like this one from Valterra.”
Good instructions except for steps 3 and 4. You should also perform the black tank flushes before emptying the gray tank. Save the gray water to be the last stuff to go thru the sewer hose before disconnecting. This provides the benefit of the soapy water thru the hose.
I recently purchased the Valterra flushing attachment, and it worked wonders on an old black tank that was neglected on a construction site for 2 years!
This RecPro holding tank sensor is much better than the ones that came in the tank. The biggest problem in my application was removing the old ones they have been in there for 12 years. And when you tried to remove the screws the rubber just turns with it not allowing it to loosen correctly. I ended up having to just take a pair of diagonal pliers and grab a hold of underneath the head and pull them out at an angle the installation was easy peasy and work perfectly.
I have one of those Valterra flushers you promote in the article. Can’t see what good it does. It just lets you fill up the tank with fresh water and then drain it. Why do I need some attachment to do that? I guess it’s faster than running water down the drain, but it sure doesn’t add any cleaning action.
Dumping a bag of ice into your black tank before you travel will not help clean it as you drive. That idea as been proven not to work. I find the best way is to put one of those water wands with the rotating heads down the toilet into the tank and letting it spin there for awhile.
I have wondered if one urinal puck dropped into a recently-emptied black tank would sink to the bottom of the tank and do some scouring while bouncing down the road. This should be more effective than ice cubes, which float in water, and melt quite quickly, They also have to be carefully dropped into the tank through the ball valve with that fragile seal; ask me how I know.
Some RVers use different materials utilized explicitly as an RV tank sensor cleaner, while I use a tank cleaning wand to clean my holding tanks.
I simply flush my black tank by filling it completely then dumping with fresh water every time I empty it. I never camp for long periods (more than a week at a time) but this has worked for many years with no issues. I never add any chemicals or additives to my black tank. I do add a little chorine bleach to my grey tank at times when I get a bad odor.
The black water tanks need to be sanitized periodically, or a number of serious bacterial infections can spread not only through the toilet itself, but into the water lines and throughout the trailer in time. Periodic flushing of these lines is critical, as is the need to sanitize the black water holding tank.