Holding Tank Dilemma

david92076 · 04-23-2009, 12:46 PM

I'm new to all this trailer responsibilities as I am upgrading from a pop-up. Anyways, I went to dump the holding tanks and it seemed both the grey and the black came out from one valve (meaning the black tank valve). Is there any suggestions on what could be going on? Seems to be not a common thing and I got people scratching their heads on this one

MACK C-85 · 04-23-2009, 01:27 PM

What unit do you have?

Sounds strange that there would only be one valve. On our T-276-SR the gray valve handle is way up high next to the frame and is extremely easy to miss if you don't know where it is. It's about five inches above the black handle, is a pain to operate, and can result in some nasty scratches from the siding edges if you aren't very careful.

Also, the valves are actually located on the tank outlets and operated by long rods attached to the handles. This keeps the pipes dry to prevent freezing.

david92076 · 04-23-2009, 01:41 PM

I have a 1990 sunline TT 24'. someone else had mentioned the grey valve could be higher, but both valves are right by the main. The only logical explanation is because there were other changes from previous owner is they installed the bottom valve and didn't remove the top valve. when I get to the trailer, I'm going to open the grey valve and turn the water on to at least make sure its not clogged. also, the grey valve is the wider ones, could that be the black water? haha, from the advice my fellow campers are giving, they've confused me

Steve Collins · 04-23-2009, 02:23 PM

David,

If you have two separate holding tanks, gray and black, then the gray water drain line from the tank to the fitting for the dump connection is 1.5" ID plastic pipe. The black water drain line is 3" plastic pipe, same as in most homes. If they are black, they are likely ABS. If they are white, they should be PVC.

Anyway, trace them both from the dump fitting back to their respective tanks. Somewhere along the way there should be a slide valve for each. On some of the newer trailers, the dump valves are way under the TT and are operated by a long rod.

However on older units, the dump valves were usually fairly close to the final dump fitting where stinky slinky connects. On my '99 2453, the gray valve is just to the left and the black valve is just to the right of the dump fitting:

If the system has been modified, it is possible that they plumbed everything to a single valve. That is not good as there are times where you might want to leave the gray side open such as when you're in a full connection campsite for an extended period. Also, it is a very good idea to be able to dump just the black first and then the gray which acts as a bit of a rinse for your drain hose and ensures that all solids are moved out of the hose before you disconnect and rinse it.

It is also possible that the gray drain line is completely clogged. Fixing that is not difficult. But don't use draino or any other unclogging chemicals.

What would be best is if you could take some pics of what you have and post them here so that we can see exactly what you are describing.