RV Black Water Holding Tank Cleaning Tips

We RV’ers have a love-hate relationship with the black tank in our RVs. We all love the convenience of having one to do our business, but hate the smell and cleaning associated with having one. Not only do we have to put up with the unpleasant smells, from time to time, but we also have to deal with the level sensors which often get caked with “stuff” which give erroneous readings (you KNOW the tank is basically empty, yet it reads completely full). In order to deal with these and other black tank issues, here are a few tips that I’ve learned along the way.

After emptying your blank holding tank, place at least a couple gallons of fresh water in it along with the tank treatment of your choice. In my experience the additive you place in your tank doesn’t really matter all that much, they all work about the same, despite their many claims. As for the toilet paper, you can not only use standard RV toilet paper, but also cheap household one-ply brands marked “septic safe” or Scotts Extra Soft two-ply toilet paper. These household brands dissolve just as well as standard RV toilet paper and often cost much less. If you don’t believe me, perform your own test by placing a couple sheets of toilet paper of your choice as well as RV toilet paper in two separate glasses of water and shake. Both should dissolve at about the same time.

Keeping your tank fresh and clean smelling and ensuring that your level sensors read properly is not that hard. After emptying your black tank, add a cup of Tide dry granule washing machine detergent (with no bleach) and a couple gallons of water. After doing this drive a hour or two, making sure that all the contents in the tank get mixed up. After doing this, dump your black tank again. Don’t forget to place two gallons of water and your favorite tank treatment back in the tank after you’re finished. If you don’t have a box of Tide detergent handy, use a bag of ice cubes instead. I’ve never used ice cubes to clean my black tank, but many RVers swear that it’s just as effective.  Clean your tank as often as needed.

Here are a couple tips to remember when dumping your tank. First, make sure you wear disposable gloves while dumping your tanks, keeping a supply of gloves handy near your RV’s dump station. Before attaching your slinky to your RV, make sure that the clamp fitting that tightens the connector to your slinky is tight. I’ve seen these detach at dump stations and it isn’t pretty (the look on RVer’s faces when this happens tells the story). You’ll also want to make sure that the other end of the slinky hose is secured to the drain with either a rock or brass lid. Doing this ensures that when you open the dump valve the slinky doesn’t lift up and leave a big mess around the dump station and on your shoes. When emptying your tanks, dump your black tank first (the larger diameter pipe), then your gray (the smaller pipe of the two). Doing this cleans the nasties out of your slinky with relatively clean gray water.

Show proper etiquette when dumping at public facilities. If there is a long waiting line, do your business as quickly as possible, then leave. But before you do so, clean the area with fresh water (most dump sites have a hose and fresh water to do this). If you need to wash your hands or do some other cleanup, pull your RV up, so others can begin dumping.

If you have any tips of your own, I’d love to hear from you.

About Mello Mike 891 Articles
Mello Mike is an Arizona native, author, and the founder of Truck Camper Adventure. He's been RV'ing since 2002, is a certified RVIA Level 1 RV Technician, and has restored several Airstream travel trailers. A communications expert and licensed ham radio operator (KK7TCA), he retired from the U.S. Navy in 2004 as a CWO3 after 24 years, holds a BS degree, and now runs Truck Camper Adventure full-time. He also does some RV consulting, repairs, and inspections on the side. He currently rolls in a 4WD Ram 3500 outfitted with a SherpTek truck bed with a Bundutec Roadrunner mounted on top.


  1. I have found that using the detergent full time in the tank even helps the solids dissolve. For the last couple of years a cup of Tide in the tank after dumping with a bit of water is all the tank treatment I have needed. My sensors now are at least repetitive if not accurate. My black tank is 35 gallons and a cup is plenty for it.

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