Recreational vehicles (RVs) come with electronic tank sensors to let you know when your black water tank is full. However, dirty sensors or sensors that are clogged with solid wastes will often register as full even when you know the tank is empty. If you own an RV with faulty tank sensor readings or want to learn more in case you purchase an RV, then you can eliminate the problem by cleaning the sensors. Cleaning them by hand is impossible due to the location of the sensors inside the top of the tank, but you can build an easy-to-use, inexpensive tool that will do the hard work for you. Below is what you will need to know about making and using the sensor cleaning tool:
Tools and materials needed
10-foot section of PVC Schedule 40 pipe in ½-inch diameter
Garden hose female threads to female ½-inch slip connector PVC adapter
½-inch PVC slip elbow fitting
PVC cutter or hacksaw
1. Cut the pipe to length - With your measuring tape, mark off 60 inches on the ½-inch diameter PVC pipe and make a perpendicular cut using a PVC cutting tool or hacksaw. Use a small piece of fine-grit sandpaper to remove any burrs or sharp edges from the end of the pipe.
2. Attach the slip elbow to the pipe - Once you have cut the pipe length, spread a generous amount of PVC cement around the first inch of one end of the pipe. Next, take the ½-inch PVC slip elbow and slide it over the end of the pipe; give the slip elbow a quarter-turn twist while installing it to spread the cement over the end of the pipe. Set the pipe aside for 5 minutes to allow the connection between the PVC elbow and pipe to bond and cure.
3. Attach the garden hose adapter to the pipe - After the PVC elbow has been cemented into place and cured for a few minutes, you can attach a female garden hose adapter to the opposite end of the pipe. Most garden hose threads are ¾-inch in diameter, but be sure that the adapter you purchase fits the male end of your garden hose.
As with the PVC elbow, apply a coating of PVC cement around the first inch of the pipe at its unfinished end. Next, quickly slip the garden hose adapter slip connector over the end of the pipe and give it a quarter-turn to distribute the cement evenly. Be sure not to allow the cement to run down into the adapter so you don't accidentally glue the movable thread rings to the base of the connector. Set the assembled tool aside and allow the cemented sections to cure for at least 2 hours before using.
4. Using the sensor cleaning tool - Once the sensor cleaning tool is assembled and the connectors have cured, then you can hook it to a garden hose and commence cleaning your sensors. To begin, attach a garden hose to a freshwater spigot; the spigot does not need to supply potable water, so feel free to use non-drinking water to save money and conserve. Attach the other end to the female garden thread adapter and hand-tighten the connection.
After the tool is attached to a water supply, slowly lower the end of the tool with the slip elbow fitting into the toilet and carefully push it through the flush valve at the bottom. Be careful not to apply force, or you risk breaking the valve. Instead, be gentle and work the tool around until it is able to penetrate the opening and push the valve aside. Lower the tool a few inches further so that the elbow fitting is inside the black water tank.
Once the end of the tool is past the flush valve, hold on firmly to the tool and ask a helper to turn on the water supply at the spigot. Water will begin flowing from the elbow toward the side of the black water tank. Rotate the tool to distribute water into the top area of the tank where the sensors are located. Move the tool up and down a few inches, as well, to aid in getting the stream of water to the right locations.
Continue washing the tank sensors and allow the tank to fill with as much water as possible; the water will also help free up any trapped debris. Once you have cleaned the sensors thoroughly, empty the black water tank at an approved dumping station