The other day I came out to find a small water puddle underneath the back of my RV. Well, to be honest, it wasn'.t really a puddle more like damp pavement. I figured it was from the fresh water overflow hose when I last filled my tank. No worries, I'd keep an eye on it. Several days go by and it remains damp each day. The damp area doesn't seem to change in size, so it must be a steady drip. Looking underneath the RV showed NO water leaking at all from any of the likely drain pipes nor water fittings that I could see. Hmmmm. I had a mystery on my hands that would have to be sorted out before it became worse.
Upon closer inspection(and in multiple awkward positions) I discovered the leak. (Really more of a "seep") For some reason the designers of my RV decided it would be a good idea to have the fresh water drain come out ON TOP OF my grey water tank! Huh? There is a small tube that comes from the water system directly on top of the grey water tank. While it does keep the top of the tank quite clean it's a bit silly. I've been thinking of running a rubber hose from the outlet to someplace better. Well... THAT WASN'T the problem! The leak was something else since the fresh water system is completely drained and "blown out" for the winter.
On my RV the sink drains all feed a common inlet to the grey water tank. There is a very short vertical PVC pipe that goes from the intersection through the flooring and sub-flooring, down to the grey water tank. It's almost impossible to see. I had to resort to using a camera with a flash to get a clear view. Anyway, when water is draining from the sinks the joints on this pipe seep a little water, very slowly. I can see someone tried to put several beads of silicone sealant around the pipe to stop the flow. This MAY have been working for a long time, but really isn't a proper repair.
To do this right, I will have to remove the retaining straps on the tank somehow and disconnect the pipe that's leaking. Problem is, I cannot see how it's threaded or attached. It may very well be PVC glued on...in that case a hacksaw and some fresh pipe is in order. I am trying to figure out how to get it all back in place. I do not believe I can get to the pipe joint while the tank is in place. This whole shebang may have to wait until the weather warms up. I am hoping I can access the leaky section without a complete disassembly of the tank and structure around it. Who knows, I may get lucky for a change! Not likely, but one can hope, right?
Next season (or right now, if you are blessed with warm weather!) you should go out and look at the TOPS of your tanks. It just might explain that mysterious slow leak that has plagued you for a long while. I was surprised.....never knew that there were fittings there.