Men sit back cause here it comes. My sister and I, yep 2 females puchased a 2005 Keystone Montana 5th wheeler for 80 year old mom. After connecting the city water and 2 weeks later after many experiences (various stories) we have a major leak that comes out underneeth trailer. We unscrewed 2 bolts from black cover underneath by front tires and water is now draining from that point- shut water off. It seems that when the water hose is on and the kitchen sink is on, is when the problem begins. Not toilet water and havent used shower yet. Yes we emptied the gray and black tanks (another leason learned hardway. We paid to move the trailer here which is not full for fulltime use and we dont know where to go from here. Is there another tank that we are not aware of and perhaps its full? do you think a hose detached? Whats the best access besides taking all the bolts off and exposing the entire underside of the trailer? I appreciate all advise! Thank you in advance for your time.

Some (not saying yours does) 5th wheels have three tanks....1 black, 1 grey (shower/bathroom sink) and 1 'galley' (kitchen sink). Each has their own dump valves. Sometimes the galley one is not with others and is back behind tires.But if tank was full it would back up into kitchen sink.The drain line from sink to tank could be cracked/broken.The undercover is plastic. Look under kitchen sink and see where drain line runs.Then with a mental picture of that location go outside and under rig.You can cut a three sided window in the plastic cover (the non-cut side should be towards front-----2 parallel cuts lengthwise front to back with a rear cut across then pull flap down). This will give you a visual on the source of leak.Got to find it before you can fix.......plus you need to get the water out of there and give it a chance to dry out (mold/mildew-----food debris if from kitchen sink)The three sided flap can be taped back shut after repairs. Lots of flaps out there cause of needs to repair with enclosed/covered underbellies.

Thank you for your quick reply. We will take a look!

We have 3 tanks on our 5'er. We have 2 valves under the bathroom area (black and gray from shower and bathroom sink) and one valve that is a PITA to get to - it's under the slide (gray from kitchen). That is probably your problem, also. Hope you can find it quickly. If you can't, are you in a campground with other campers. Do you know any of them and could ask? Is there anyone that walks around the campground that seems to be friendly? Is there a camphost? Those would be my suggestions.

Did your rv come with manuals. If it did I would start by reading the manuals front to back. These units can be fairly complex. Between your manual and the forums, you should be a veteran in no time. Make sure if you live in an area that freezes that you understand the importance of draining your water systems and how to do it. good luck and enjoy the new rv.

With or without a galley tank under your trailer your leak is much more likely to be coming from a pressure water line. You say it leaks most with the kitchen sink water running so it could also be the drain from the sink to the tank (whether it's a galley tank or all in one gray tank).Good luck / Skip

Major water leak coming out underneath trailers black cover

13 Replies

Merrykalia
Explorer II
Feb 11, 2014
We have 3 tanks on our 5'er. We have 2 valves under the bathroom area (black and gray from shower and bathroom sink) and one valve that is a PITA to get to - it's under the slide (gray from kitchen). That is probably your problem, also. Hope you can find it quickly.

If you can't, are you in a campground with other campers. Do you know any of them and could ask? Is there anyone that walks around the campground that seems to be friendly? Is there a camphost? Those would be my suggestions.
dhsmontana
Explorer
Feb 11, 2014
Thank you for your quick reply. We will take a look!
Old-Biscuit
Explorer III
Feb 11, 2014
Some (not saying yours does) 5th wheels have three tanks....1 black, 1 grey (shower/bathroom sink) and 1 'galley' (kitchen sink). Each has their own dump valves. Sometimes the galley one is not with others and is back behind tires.

But if tank was full it would back up into kitchen sink.
The drain line from sink to tank could be cracked/broken.

The undercover is plastic. Look under kitchen sink and see where drain line runs.
Then with a mental picture of that location go outside and under rig.
You can cut a three sided window in the plastic cover (the non-cut side should be towards front-----2 parallel cuts lengthwise front to back with a rear cut across then pull flap down). This will give you a visual on the source of leak.

Got to find it before you can fix.......plus you need to get the water out of there and give it a chance to dry out (mold/mildew-----food debris if from kitchen sink)

The three sided flap can be taped back shut after repairs. Lots of flaps out there cause of needs to repair with enclosed/covered underbellies.

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Major water leak coming out underneath trailers black cover

13 Replies

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