An RV holding tank needs regular care and attention to stay in good condition, but it is difficult to look inside the tank. I have seen so many posts by campers who are having black water tank problems. To solve some of your issues this post is about how to install an inspection / clean out port on your tank.
Start With The Right Fitting: 1 1/2″ ABS Clean Out Adapter
Start by buying a clean out ABS clean out adapter with a gasketed thread in cap so that you can open the port and when done reseal the port.. This is a commonly used fitting and is readily available at most hardware stores. Find a spot on the side of the black water tank that is accessible for both the install and future inspections. Using a 1 1/2 inch hole saw cut a hole in the side of the tank. Make sure you will be able to run a bead of Easy ABS Repair Resin around the fitting without hitting any obstructions.
Cut The Hole + Install The Adapter
Clean the saw burrs from the hole and wire brush the area. Run a bead of easy ABS repair resin around the shoulder of the fitting and insert it into the hole. Use a strip of masking tape to hold the fitting tight into the hole and against the tank. Allow the easy ABS repair resin to air cure for 24 hours before removing the tape.
Run a Continuous Bead Of Resin Around The Fitting
Apply a bead around the fitting where it meets the tank. As the resin cures it welds the ABS plastic to the tank. The bead should be continuous. the resin will air cure and become as hard as the original plastic.
You Can Now Clean Out or Inspect The Black Water Tank At Any Time
You now have a removable sealed inspection plug in the RV holding tank. Inspections can be made of the inside the tank to check for built up matter that may be causing issues. . A hose can be inserted to better flush the tank or use a wire coat hanger to break up the clog.