How to Unclog an RV Black Water Tank

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What You'll Need
Power washer
Liquid cleaner
Johnny Chock
Manual auger
Flexible piping or sprayer
Chemical solution

If you find that your RV black water tank has become clogged, then you need to remove the obstructions as quickly as possible. Blockages in the waste tank can quickly turn into a backed up toilet, leading to sewage leaks, dirty water all over your floor, and eventually, expensive repairs. Getting rid of clogs should not be too difficult, and by following some simple steps, you should have the RV black water tank clean in no time.

Step 1 - Use a Power Washer

If you think that the problem with your RV black water tank is in the tank itself, then the first move is to give it a really good wash. Empty the tank at a convenient location, and then using a power washer, clean the inside of the tank. Apply a good layer of liquid soap to the inside surface to remove any built-up grime.

Step 2 - Clean the Line

The most common location where problems occur is in the line between the toilet and the waste tank. This often becomes clogged with hard material, called "pyramid" plugs. If you don't properly maintain your waste tank, these can become frequent.

One solution you can try is to fill half the tank with water, and then add some liquid soap. Drive around some rugged roads, sloshing the water around to agitate the mixture. Run water through the pipes afterward, leave it for several hours, and then flush a few times to see if the line is clear.

If the previous option doesn't work, buy or rent a hand-operated auger and feed it down the pipe, through a Johnny Chock to keep the drain open, into the mound to loosen it up. Then, follow this up by feeding either a flexible, lengthy spray wand or some type of flexible piping that can attach to a hose down the drain to clean the loosened debris away using water pressure.

Remember that pyramid plugs will keep reoccurring if you are not taking proper care of your holding tank.

Tip: Do not use a motorized auger for clogs in a RV black water tank. You can easy puncture or damage the tank itself.

Step 3 - Use Chemicals

Some chemical treatments can be used to break down solid matter clogging the tank. There are many varieties available on the market, but most require a lot of time and possibly several applications to work. Just make sure to follow the packaging instructions on whatever you buy and have patience.

Step 4 - Maintain and Prevent Future Clogs

Always make sure your waste tank is about 3/4 full with water before draining it, and then make sure to fill the bottom up again afterward. Also, make sure that you only ever use cleaners, deodorants, and toilet paper approved for holding tanks so you don't end up with too much solid waste accumulation. Harsh household drain cleaners can interfere with the breakdown of waste in the tank and can damage the seals on the drain valves.