RV Black Water Tank Removal

RV Black Water Tank Removal
RV repair facilities charge a hefty price to work on black water tanks--anywhere from hundreds to thousands of dollars, depending on the repair--because they have to work with your sewage. Removing, repairing and replacing an RV black water tank is an unpleasant job and is at least a day long project, but the cost savings makes the work well worth doing yourself.


Difficulty: Challenging

Remove the Toilet

Things You’ll Need:
  • 12-inch socket wrench
  • Screwdrivers (various sizes)
  • Hacksaw
  • Floor jack
Step 1
Empty and flush out the black water and gray water tanks.
Step 2
Turn off the city water connection to the RV and the RV water pumps.
Step 3
Disconnect the water line that enters into the back of the toilet.
Step 4
Remove the nuts from the closet bolts, located at the base of the toilet, using a 12-inch socket wrench.
Step 5
Lift the toilet off the bolts.
Step 6
Peel the toilet gasket off the flange and discard it. Install a new toilet gasket when you reinstall the black water tank.

Remove the Flange and Detach the Vent Pipe

Step 1
Unscrew the screws that hold the flange to the floor, using a screwdriver.
Step 2
Twist the flange counter-clockwise or pull it upwards to remove it from the black water tank, depending on how it is installed. If the flange is cemented into place, cut it off using a hacksaw and re-cement it into place when you reinstall the black water tank.
Step 3
Climb up on the RV roof and remove the black water tank vent cover.
Step 4
Detach the vent pipe from the black water tank. To do this, unscrew a vent pipe that leads straight to the black water tank. If the vent pipe does not unscrew, it is most likely a wet vent (a vent that is shared with a sink) or a vent that curves before it meets the black water tank. If you have a wet or curved vent pipe, remove it at the closest accessible point where it meets with the black water tank. To find an accessible point, climb down from the RV and look inside cabinets and under sinks inside the RV for the vent pipe. Cut the vent pipe using a hacksaw. The cut vent pipe needs to be re-cemented when you reinstall the black water tank.

Remove the Black Water Tank

Step 1
Remove sensors and probes attached to the exterior of the black water tank.
Step 2
Remove the dump valve assembly. Most dump valve assemblies unscrew and are removable using a screwdriver. Some dump assemblies, however, are cemented in place. If cemented, use a hacksaw to cut behind the dump valve assembly and separate it from the black water tank. Upon re-installation of the black water tank, re-cement the dump assembly in place.
Step 3
Inspect the black water tank to determine how it is installed in the RV. Some black water tanks are mounted underneath the RV and held in place by straps or metal bands. Other tanks are set inside a compartment--secured in place with wood blocks or not secured at all.

Pull a black water tank set in a compartment out, removing the wood blocks first, if necessary.

Support a black water tank that is mounted underneath the RV with a floor jack before removing the supporting straps or bands. After removing the straps or bands, lower the jack slowly to bring the tank to the ground.

Tips & Warnings

Some RV owner's manuals contain diagrams that show how the vent pipe and black water tanks are installed.
There are many variances in how black water tanks are installed in different RVs. To avoid damaging the waste water system in your RV, do not attempt removal of the black water tank until you are certain you understand how it is installed.

Article Written By Rose Kivi

Rose Kivi has been a writer for more than 10 years. She has a background in the nursing field, wildlife rehabilitation and habitat conservation. Kivi has authored educational textbooks, patient health care pamphlets, animal husbandry guides, outdoor survival manuals and was a contributing writer for two books in the Uncle John’s Bathroom Reader Series.

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