Full-time RVers use their waste tanks constantly. We don’t use them only on weekends or holiday vacations then clean them up and put into storage. Nope, we are filling our tanks, dumping them, filling and dumping, again and again. Over time, debris can build up, especially in the black tank.

So, flushing out your black tank is a must. It helps keep your tank sensors clean, keeps odors from developing, and will extend the life of your tank system. Some RVs have a tank rinse system built in making it much easier to flush out the tanks every time you visit a dump station. But many of us have to do it manually. In this post, we’ll look at different ways to flush out your RVs black tank.

NOTE: I suggest flushing your black tank at your campsite when you have full sewer hookups. You could flush your tank at the dump station, but you run the risk of being rushed if there are other RVs waiting behind you, unless that’s your only option.

How Often Should You Flush Out Your Black Tank?

if you’re using your system properly by adding the proper chemicals to dissolve solids, using plenty of water when you flush, and minimizing the amount of toilet paper you put in the tank, you should only have to flush your tank every 3 months, or once a quarter. However, if you start to notice an unusual amount of foul odors when your tank is more than half way full, it’s probably time to do a good tank flush.

Flushing With the Black Tank Wand

On simple and inexpensive tool you can use to flush your black tank is the wand. A wand is a simple plastic tube, with an on/off valve, that attaches to the end of a garden hose. On the end of the wand are holes that spray the water in multiple directions. To use the want you’ll need to run a hose from the outside faucet to your RV bathroom. Depress the toilet pedal and place the wand down the toilet and turn it on. Let the sprayer run until the tank fills up completely. Then turn it off and dump the tank.

Repeat this process until you see the water run clear and you see no more solid waste coming out. (This is why you should use a clear elbow on your sewer hose.) The wand does a fairly good job and spraying the sides of your tank, but because it doesn’t bend, it’s not really reaching all the corners of your tanks. But, it’s good for filling the tank with water.

Flexible Black Tank Wand

A flexible wand works the same way as the previously mentioned wand, but because it’s flexible, it can reach deeper into the black tank. This allows it spray the top of the tank and hopefully spray directly on the sensors and rinse any gunk or debris away, which is the main reason why tank sensors never work properly.

I tried using the Camco Swivel Stick but that one didn’t work for my system. The sprayer at the end of the swivel stick is too large and I couldn’t get it to make the 90 degree turn to get it deeper into the tank. It may work for others with a different plumbing layout, but it didn’t work for my system.

All metal, stainless steel swivel sticks have a smaller sprayer and and a longer flexible hose. Whit this, I was able to get the sprayer around that corner and deeper into the tank. This sprayer is also great for tanks that are offset from the toilet.

Reverse Flush Valves

An RV black tank reverse flush attachment is a device that helps clean out the waste and residue from your black tank by forcing pressurized water back into the tank. This reverse flow helps dislodge stubborn debris. Before using the flush valve, empty your black and gray tanks as usual. Next, connect the attachment to the tank’s flush outlet. Attach a hose to the fitting. Never use your fresh water hose for this. You should have a standard garden hose on board for things like this.

Next, with the valve on the attachment closed, open the black tank valve and turn on the water supply. The pressurized water flows up into the tank, agitating and breaking up any remaining waste or buildup. After a few minutes, close the water supply and open the flush valve allowing the tank to drain completely.

You’ll see debris such as toilet paper that didn’t break down, passing through the clear attachment, which can be kind of gross, but necessary to ensure your tank is truly clean. Repeat the process until you no longer see any solids and the water runs clear. You can repeat the process with the gray tank too, flushing out any food build up until the water runs clear.

There are a couple of reverse tank valves available that can be found at most places where RV products are sold. The two most popular are the Rhino Blaster Pro and the Valterra Flush King. I use the Flush King but I’ve heard that both of them work great.

Clean your Black Tank While Traveling

Besides using gadgets and attachments to flush your tanks, there are a few ways to give your tank a deep clean while you travel to your next stop. Here are a couple methods.

When you leave your campground, dump your tanks as you normally would. Then take a few bags of ice and dump them down your toilet adding just a few gallons of water to it. Don’t add too much water because ice floats which defeats the purpose. The theory is that as you drive, the ice will slide around the bottom of your tank acting as a scrubber and loosen debris. The ice will melt along the way so when you get to your next destination, fill the tank at least 3/4 of the way with water, then dump it as usual.

If you notice solids coming out of your tank when you dump it, then this method worked. I’ve tried it a couple of times and it seemed to pull a bit of more gunk from my tanks.

Another similar method is the GEO method. This method is a mixture of Calgon water softener and a detergent such as Dawn dishwashing soap. Other RVers recommend using a mix of Calgon and Pine-Sol. After dumping your tanks, fill them about 1/2 full. Next, add an ounce of Calgon along with a couple ounces of Pine-sol down the toilet. While you drive to your next campsite, the treated water will slosh around breaking down grease and build up. When you arrive, dump your tank and rinse it at least once.

You should never use anything with bleach to clean your tanks as bleach can cause damage to the tank’s seam and seals.

Conclusion

No mater what method you use, giving your black tank a good flush out on a regular basis will help prevent nasty clogs, prevent foul odors, and keep your tanks, sensors, and seals in good working condition.