How to Clean Sensor Probes on a Black Water Tank


Black water tanks are dirty places. Sludge and toilet tissue can accumulate on the walls of the tank and stick to the sensor probes, causing inaccurate gauge readings. RV sewage maintenance is tricky when you cannot accurately determine if your tank is empty or full, and can lead to overflow accidents that are a nightmare to deal with. Fix the problem of inaccurate readings due to dirty sensor probes with a thorough tank cleaning.

Things You'll Need

  • Latex gloves
  • RV sewer hose
  • Garden hose
  • RV black water holding-tank treatment product
  • Put on a pair of latex gloves before cleaning your black water tank, to minimize your exposure to sewage from accidental spills or leaks.

  • Attach one end of the RV sewer hose to the black water-tank outlet on your RV. Attach the other end of the RV sewer hose to the RV dump-station sewer connection.

  • Open the valve on your RV black water holding tank, and allow the contents to empty into the dump-station sewer.

  • Clean the black water tank with fresh water by attaching one end of a garden hose to a fresh-water spigot and the other end of the hose to the RV black water tank water inlet, if equipped, or a rotary tank rinser, if you have one installed. Turn on the water at the spigot and allow it to spray into the tank – with the black water valve in the open position -- until the water comes out clear, or for 10 minutes. If your RV is not equipped with either a black water-tank water inlet or a rotary-tank rinser, close the valve on the black water tank, add water through the RV toilet to fill the tank, and then open the black water tank valve to empty the water into the sewer.

  • Close the valve on your RV black water holding tank.

  • Fill the black water tank half full with water. Filling the tank half full takes a little guesswork on your part when the holding tank gauge readings are inaccurate. The exact amount of water is not crucial, and it's fine if you end up with a little less or more than a half full tank.

  • Flush a black water-tank holding treatment product down your RV toilet. Either use a commercial enzyme-based or heavy detergent-based RV black water tank-treatment product, following the manufacturer’s directions regarding the amount of product to use, or use ½ cup of liquid dish-washing detergent.

  • Disconnect the sewer and water hoses from the RV and dump-station connections.

  • Take your RV for a 30-minute drive to allow the water and holding-tank treatment product to splash around in the tank and loosen stuck on debris from the sensor probes. Afterward, drive back to the dump station and empty the tank. If you used an enzyme-based holding-tank treatment, do not empty the black water tank until the next day.

  • Clean out the RV black water tank with clean water again, and then check the black water holding-tank gauge to see if it reads correctly. If the gauge still shows an inaccurate reading, repeat the above steps again. It may take several attempts to completely remove sludge and toilet paper from the sensor probes.

Tips & Warnings

  • A garden hose used to clean a black water tank should not be used for any other purpose, because it may be contaminated with harmful bacteria.

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