Gray tank water leak

Warm weather finally arrived, so its time to de-winterize the “New-to-Us”  Southwind and check out the water systems.

The previous owners had made some minor modifications to the water system,  replaced the water pump and removed the “bypass valve”, which is used to fill the fresh water tank directly from the city water connection.  This isn’t a big deal for now, since the fresh tank can be filled by the gravity feed.

I filled the fresh tank and I added a cup of bleach to sanitize the systems while testing.  I ran all the faucets, toilet, shower, and turned on the hot water heater to check for leaks. I ran the water into the gray and black tanks to about 1/2 full, and then declared the water system operational.  NOT SO MUCH…..

DRIP – DRIP – DRIP

Later in the evening,  I noticed water dripping under the Southwind.  The inside of the coach was dry, so it wasn’t coming from the fresh tank.

I started google searching what it would take to get to the gray and black tanks. There wasn’t a lot, other than the tanks were located between the frame rails and were not accessible without ripping up the floor.  OMG.  I started tracing the drain pipes, looking up from the wet bay,  I could barely see a large cavity behind the tanks.  I went around the other side of the Southwind and looked in the storage bays and made a very fortunate discovery.

Fortunately for me,  the previous owners had a problem with something in that cavity and cut an access hole in the rear passenger side baggage compartment.  The hole had been covered over very neatly duct tape and was painted the same color as the compartment.  I removed the tape and behold,  there was a small opening cut and I could see up inside the cavity where the drain pipes were.located.


I stuck my hand in the hole and felt around, it was wet toward the back of the cavity,  but dry toward the front where the tanks were.  . I cleaned the area with a bunch of paper towels, then put my phone camera on record and reached in as far as I could to record the pipes.  I’d hold the camera for a few seconds,  then move it a little, and hold it still again.  Since I couldn’t see, I was basically trying to catch something on film and find out where the leak was coming from..

After reviewing the video,  I found a few seconds where the camera was looking right at the gray drain pipe and the leak was obviously coming from the bottom of that pipe, BAM,  found the leak.  I reached in with my hand and thought I could fell a crack near the bottom of the pipe. Probably at some point in the past,the pipe wasn’t drained completely and the standing water in the pipe froze and split the pipe.

I was able to get a small saber saw in the opening and cut one end of the bad pipe about 4 inches behind where it exits the gray tank.  I then went around to the other side and in the wet bay, I moved wire bundles and some of the plumbing out of the way, and was able to cut the drain pipe about 2 inches back from where it enters the gray tank dump valve.

I pulled the bad section of pipe out and found it had a split in it about 2 ft long.  I bought a new elbow and a 5 ft section of 1 1/2 black plastic drain pipe.  I cut the new pipe about 1/2 inch shorter than the old one and glued the pieces to the new elbow. Rather than gluing the new section in,  I used two of those rubber connectors to join the ends of the new pipe to the old pipe.

I filled the tanks with water and let them sit overnight,  no leaks.

3 Replies to “Gray tank water leak”

  1. Pingback: Winterize - FAIL - Broken water pipe - 1999 Southwind 35S

  2. Good day! can you help me and tell me how to get to the replacement or repair of the black and gray tank? where do you need to open the floors to get to them? I will be glad for any help. Thank you

    • OUCH —- On mine, I can see the back of the tanks if I look in where the water panel is, follow the black and gray drain plumbing and you can see the back of the tanks.. I’m not sure how I’d get to them if I had to do a major repair.

      Mine are located in the center, between the two sub frame rails, I think the front of the tanks are about even with the toilet. Going in through the top might be the easiest way, cutting through the floor in the hall beside the bathroom

      The toilet does a little turn then drops straight into the black tank.

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