Thursday, September 21, 2023


Ask Dave: Why is my gray water tank leaking and how do I fix it?

Dear Dave,
I have a 2006 Coachman Epic. The gray water tank is leaking from the bathroom only. How can I get to it and fix it? —David

Dear David,
The Coachmen Epic is a Class A motorhome that was available in several floorplans. Typically, the gray water tank would accommodate the shower and bathroom sink. I’m not sure if the kitchen sink also goes to the tank, so today we will concentrate on the shower and bathroom sink.

Gray water tank inside leaks

The shower dumps straight down the drain to the tank. Sometimes it does so with a slight bend, but that typically would not be a point of leaking unless the drain itself is not sealing. My first question is: Where do you see the leak? If it is underneath the unit, I would start with resealing the drain and grate and then inspect the edge of the basin where the shower stall connects to the base. Typically, the wall of the shower comes down inside the flange of the basin and doesn’t need much sealant, if any. However, if the wall comes down flush to the basin edge, it could leak there. It could also be a crack in the basin or shower surround.

My second question is: When do you notice the leak? Is it consistent or when the tank gets close to full? If it is close to full, then it would be wise to conduct a low point water test, which consists of filling the gray water tank through the shower and inspecting all connections until the shower basin starts to fill.

Another leak potential could be the connection of the bathroom sink to the tank. It could be loose or even disconnected. If you can inspect the leak and see if the water is clear or soapy, this could help identify the source as being either the sink or shower. Also, keep in mind the kitchen sink might also drain into the gray water tank. The pipe connection to the tank could be loose or broken and it might seem to only be leaking from the bathroom.

Gray water tank outside leaks

Leak potentials outside could be the actual tank having a crack or the connecting drain pipe and various connections. Again, identifying the location of the leak could help isolate the source.

From my experience, a gray water tank leak is generally a drain pipe that is supposed to be attached to the tank has either cracked or come loose. If you can gain access to see the top of the tank, you might see a gap from the pipe to the tank.

Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.

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Dave Solberg
Dave Solberg
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.


  1. This article is a frustrating waste of time. The title says it will also tell us how to fix it but never does.
    The article is more suited to an industry magazine, like an airline magazine, than for actual RV owners.


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