Originally Posted by John Greenlee
Thank you for your reply. I have been studying my coach a little this afternoon and determined that the black water tank is indeed under the floor. I will say that evidence of leaking was significantly reduced Saturday after more properly securing the cap on the outlet and opening the black water valve so the gray water could flow into the tank. Saturday a.m. when we got up there was water standing in the tub. This concerned me as I thought it indicated a full tank. I hooked up and drug the coach down to the dump station. I looked like Chief Inspector Clouseau emptying the tank -- I did everything wrong. However, the enviornmental police did not catch me and I learned quickly from my mistakes.
Now, is it likely to have a leak in the black water tank? I made a wet spot on the ground under the rear of the coach, but not a puddle. Is it more likely my problems are related to the valve and cap combination? If necessary, how difficult is the tank to repair/replace? How expensive? Am I likely to do 20 years in the pen for a drip?
Thanks in advance for your assistance!
The black tank in your coach likely has a capacity of 8 gallons to no more than 15 gallons. The Black Water tanks in both my Overlander and Minuet are under 10 gallons. It doesn't take long to fill the Overlander's tank up when the gray water is backed up into the Black Water tank, and the evidence of being full is when the drain in the bathtub experiences backup issues.
It is quite difficult to pinpoint the source of such leach as there are a number of potential culprits. The gate valve (dump valve) has seals that can become worn with age, but the good news is that rebuild kits are available - - and unless a previous owner has changed it out, your coach should have a Thetford dump valve. Another possibility (and this has happened to me with both of my coaches) is that the dump valve/terminator plumbing may have been drug on the ground/pavement if the coach was near to being "high-centered" on a bad road - - this can cause multiple damage issues with the plastic plumbing pieces (breaks, shattered componets, etc.), this type of damage is usually readily visible. The two issues above can usually be addressed without dropping the belly pan.
If neither of the two above issues appear to be the culprits, the belly pan will need to be dropped (at least partially). Care must be exercised as it is possible that the supports that hold the tank between the frame rails may have failed due to corossion and the only thing supporting the tank may be the bellypan - - this is admittedly a worse case scenario, but a possibility. If dropping the bellypan doesn't reveal problems with the plumbing near the tank, then the tank itself may need to be dropped to find the leak(s). Dropping the tank will require removal of the toilet which of requires extra long screwdriver/socket set extensions to access all of the mounting bolts (done from inside the coach). Once out of the coach, the tank can be assessed to determine whether it is repairable - -or if a replacement will be necessary. Thus far, the black water tank in my Overlander is still the original which hasn't required repairs beyond switching from the original metal dump valve assembly to a new Thetford unit - - the Minuet on the other hand has had to have its tank repaired as it had multiple cracks along the top of the tank. My Airstream dealer handles virtually all of my maintenance work so I have only observed the repairs so don't know the precise materials used in the tank or in the repairs.
If the leakage isn't obviously black water, there are some other potential sources for leaks at the rear of the coach. The first that comes to mind as it has happened to me as well as several acquaintes is the failure of one of either the pressure regulator (built-in part of the plumbing on the incoming city water line) - - a small pipe or hose discharges the water under the coach when the valve fails or if its pressure rating is exceeded by the incoming city water; the second possibility is a leaking switch valve (your coach may not have one of these) that switches from city water to the demand system (the one on my Overlander was leaking when I purchased the coach in '95). Low point drain valves can leak or partially close allowing leakage to be present - - usually from a tube or pipe under the coach (this is an annual problem with my Minuet). Water heater may be leaking - - from drain valve, the tank itself, or plumbing around or near the tank.
Wherever the leak is coming from, it is advisable to find it and repair. If the leak should happen to be near any frame members or the floor, the resulting potential for rot isn't something to be taken lightly. In addition, the leak may have already saturated the insulation which may provide a breeding ground for mold, mildew as well as providing the potential of harboring insects.
Good luck with your search for the elusive leak!