It seems our dealers are always called out for black tank clogs. We’re not sure what everyone’s doing with their RV (or not doing!), but clog calls are so common these days that one of our dealers calls themselves “Clogs R Us”!


Black tank clogs are primarily caused by one of two factors:

  1. Toilet paper and waste build-up. There’s really no way to reduce the amount of human waste you put into your tanks, but by being reasonable with your toilet paper use, you can reduce the possibility of a tank clog. Most tank clogs are a result of too much toilet paper and not enough water (see below for water usage tips).
  2. Tank valves left open. Many RVers unfortunately leave their gray tank valves open to drain off gray water, but some even leave their black tank valves open as well! This is a monumentally bad idea as liquid (water and urine) slowly drain off, leaving behind solids to mound up. Sometimes tank valves down’t close completely and a similar situation can occur (so make sure those valves are functioning properly).


It goes without saying — and every RVer claims to know this — but using A LOT of water in your RV’s toilet and tank is key to reducing the risk of a black tank clog. Follow these best practices when using your RV:

  • Priming the system. Before each use of your tanks, add three to five gallons of fresh, clean water to them. Do this either by flushing water down the toilet (the typical RV toilet contains about a gallon of water in the bowl), pouring water down the toilet with a bucket, or using your RV’s black tank flush system to meter in the water (the Save-a-Drop water meter is great to measure the right amount of water). By adding water into the tank before use, you keep things diluted and reduce the risk of clogging.
  • The two-flush system. When using the toilet in your RV (no matter what you’re “doing”), get used to filling the toilet bowl, flushing it down, then refilling it and flushing down again. By flushing two toilet bowls of water, your black tank will keep hydrated and solids will stay suspended in the water.
  • Traveling water. We always recommend that RVers travel with five to ten gallons of fresh, clean water in their holding tanks. When you are leaving your RV park, resort, or campground, empty the tanks like you normally would, go through your tank rinsing/flushing process, and then fill the tanks with clean water for your trip home or to your next destination. The fresh water moving around in the tanks will help to dislodge any solids and keep the tank clean. Be sure to empty out your “traveling water” before starting your next camping experience or if putting your RV in storage for a while.


Knowing how RV tanks work and the waste handling system in general is a first, good step in self-maintenance on your RV tanks. Your RV’s tanks are part of a holding system. When you think about this, remember that the more liquid (mainly, water) you have in the tanks, the less likely you are to have a clog. Using adequate water — especially in the toilet — will keep things in the tank and not in the pipes or toilet itself.

With this in mind, adding tank additives that break down, dissolve, or liquify the tank’s contents is a bad idea. Why? While this sounds like a good idea, you are converting your holding tank into a septic system, where waste suspended in water is converted into a thick, sticky mess. That sludgy tank is now much more likely to contain clogs, emit odors, have sensors that habitually misread as false, and have drainage problems.

You might also consider your tank emptying and rinsing process:

  1. Empty tanks when they are 75% to 100% full. Adding more water to a tank to raise its level before emptying is a great idea to reduce the occurrence of clogs.
  2. Turn on the tank rinser/sprayer during emptying. More water through your onboard tank rinser helps to reduce the risk of clogs and the added turbulence of the spraying water during empty can help to clean off tank surfaces, such as corners in the tank.
  3. Using a tool such as the Valterra Flush King Reverse Flush Valve periodically will help to give your RV tanks a thorough cleaning, reducing the risk of tank clogs. It’s the one piece of equipment (along with the Save-a-Drop Water Meter) that we recommend EVERY RVer have in their tank emptying and cleaning kit.


Kleen Tank Authorized Dealers are uniquely qualified to resolve and eliminate clogs in your RV’s toilet and tanks. We have the training, experience, and equipment that can handle any type of clog. In fact, our dealers are recommended by their local RV techs and RV park management to help customers in these situations.

With every clog appointment we go to, we will also clean out your RV tank using our hydrojetting technology. With over ten times the pressure and penetration of your onboard spraying/rinsing system, our equipment will literally scrub your tanks as clean as they were when they came from the factory.

If you have a tank or toilet clog, give one of our authorized dealers a call. You can also reach out to us at 844-KLEENME any time and we will help you with advice on how to handle your toilet or tank clog.

Jim Tome, Owner

Jim Tome, Owner

Hi, I'm Jim Tome and, along with my wife, Debbie, the owners of Kleen Tank LLC, the national leader in RV holding tank cleaning service. We've been RVers like you since 2004 and have traveled all over the U.S. in our Airstream travel trailer. We started the business about twelve years ago and have cleaned tens of thousands holding tanks in thousands of RVs. From tiny weekend travel trailers to monstrous fifth wheels to luxurious motorhomes, I've seen just about every situation there is with RV holding tanks and waste systems. I hope you enjoy our articles; I try to post at least one per week and we've got a great library of them to cover just about every problem. Enjoy!


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