After noticing a very foul smell coming from my fresh water holding tank I needed to clean it out. My main tank is located under a step platform, the way my tank fills is through the city water connection on the service side of the rig. I needed to get bleach or vinegar into the tank but was unsure how to since the tank HAD no access. I found online a couple of access hatches that you can cut into the top of the tank, they where expensive and I did not want to wait. So I went to the nearest Big Box Store, purchased a 2" hole saw and a Red compression cap, the type with a wingnut on top, and a rubber gasket . As you turn the wingnut the gasket on the back side expands. These caps are usually used to close off the end of a pipe. After I cut a 2" hole in the top of my tank I placed the cap in the hole, gave the wingnut a few turns, and the cap tightened up perfectly. This really worked out well and only costs about $14. If you need to create access into you holding tank give this a try. If anyone needs just ask and I will give you the exact specs on the cap......happy camping, G

nice Gene...........in the plumbing world that cap is called a test plug.....they are used in final testing for inspection and will hold up to 100psi air pressure.......although from personal experience they tend to hurt if not tighten correctly upon impact!!!......LOL

I save myself all the work by putting the bleach in an empty water hose and then hooking it up and putting water into the tank.

If you have a removable cartridge type water filter(s) can't you also remove the filter(s) put the bleach in the canister and fill the tank that way?