Community Forums

richard1 · 02-28-2012, 09:07 AM

A while back, I posted a question concerning a bad odor smell coming from my kitchen sink. It seemed to be the worst when the sink was drained. Thanks to my engineer minded wife, the problem has been discovered! When the sink drains, the air that is displaced from the holding tank escapes through the tank vent which must located somewhere under the kitchen sink area. This foul smelling air is entering the living area from under the sink through the hole where hoses and wires enter.
Fix: Leave the drain valve open all the time! This prevents any air from being expelled up through the vent and therefore, into the living area.
Next I'm going to put her to work on...!

Davdeb1 · 02-28-2012, 09:12 AM

Sounds like you need to sanitize and flush that grey tank. I like to leave the grey tank with liquid in it so I can drain it through the sewer hose hose when I drain the back tank

LVJ58 · 02-28-2012, 09:16 AM

Interesting, the holding tanks on our coach are vented on the roof. I found the most common cause of grey holding tank odors getting into the coach result from dry p-traps for the sinks and/or shower drains. You shouldn't have to leave your drain valve open as a cure for the problem.

Turn Key · 03-03-2012, 08:13 AM

Sounds like there is something wrong there. Vent stack should run all the way up and out on the roof. If it's exiting anywhere else, there is leak in the vent stack or the vent stack is clogged and venting where it shouldn't.

Most people who get into trailers are surprised to find that their "grey" water smells much worse then the "black". This is because we tend to "treat" the "black" water while leaving the "grey" tank to fend for itself. This allows for a good bit of pent up stink. It is a good idea to rinse the "grey" tank often and treat it with chemicals (different one then the ones used for "black" tank). K-Z recommends rinsing the "grey" tank with a mix of clean water and Dawn dish detergent. I like to do this at the end of a long trip and at the end of a season. I fill the "grey" tank about 1/3 full and add a couple of real good squirts of Dawn. I then just pull the rig room and put it in the drive. When I have the time, I drain the tank, add my chems and go on.

Hope this helps and,

Happy Camping!

jherrin99 · 04-17-2012, 09:25 PM

All the sinks in my Class A have a drain vent under the sink. They work like a check valve and are only supposed to allow air to be sucked into the drain when it is draining. However if they are leaking they will allow the grey tank to vent back into the coach. They can be purchased at any home improvement store that stocks PVC plumbing supplies. I replaced mine for less than $6 each from Lowes. You can find them if you trace out the drain line after the P trap. There is a T and a piece of pipe sticking straight up and at the end of that pipe is a vent that screws into the drain pipe. Your drain has to be vented. If it is not vented up through the roof then more than likely it is vented under the sink. Most homes will have a drain vent through the roof at each drain. If it is not practical to vent each drain through the roof, they are usually vented this way.