View Full Version : Order from sewer line coming into RV

05-28-2013, 12:31 PM
I recently bought a 2005 Doubletree Mobile Suite. I believe I am the 3rd owner and know the second owner lived in the RV for nearly 2 yrs while building his home. This problem seems to have developed since I purchased the unit. I can't leave the lines open because the sewer odor comes back into the RV, especially in the PM when the outside temps rise. The toilet seems to seal OK but where else is there a valve that may be open and allowing odor to come inside? I could really use a schematic for the entire systems as I am also having trouble with the fresh water supply from the park water source, no water pressure. Any help will be greatly appreciated.

Oh, Doubletree says it could be calcium or rust build up in the city supply line at the check valve. Where is that valve and how hard is it to clean or replace? Again, thanks for any help you can give.

05-28-2013, 03:40 PM
I think the check valve should be located in the connection where the fresh water hose is connected. You can reach it by going in behind the sliding door in the basement--it will help somewhat to be a contortionist.
Others have said it isn't too bad a job, just hard to reach it.
Water flows in logical directions--follow the inlet line to an accessible connection with a hose clamp, if there is one. Take the clamp loose and pull the hose off--turn on the water--if no flow, it it blocked.
Do you not have ANY water pressure ANYwhere in the trailer?

05-28-2013, 06:04 PM
There is a small fine screen where the hose attaches to the trailer, look to see if that might be plugged or restricted with crud. Just to make sure that the park does have decent water pressure before blaming the trailer. The sewer odor could be loose connections at the black tank to toilet seal. Could be the valve that is connected to the handle you pull to open and close is leaking into the basement underbelly. If you decide to cut an opening under the plastic bottom to have a look, let me know and I will explain how I did it so you can reseal the opening without having any issues.

05-28-2013, 10:53 PM
By the way, the black tank is easily visible behind the sliding basement doors, as is the control valve that drains the tank. While you are looking for the check valve in the water line, the black plastic line with the square fitting in front of you is the black tank drain line. Follow it upwards to the black tank.

05-28-2013, 11:11 PM
Re: Odour....check under the sinks for the odour. I've had a bunch of vacuum breakers go bad and they are located under the sinks and allow tank odours. They are high up on the 1.5" black drain pipes and screw in, hand tight. If you don't know, they are cheap ($2) black plastic plug type fittings that dead end a pipe. If like you say the odour only occurs when your dump valves are open, my advise won't help.

Cheif 2
05-29-2013, 06:03 AM
I hope you are not leaving the black tank valve open all the time. That will cause you considerable headaches soon when the waste material hardens in the tank. Something to check is the drain for the washer. If you have no water in the p-trap you will get odors. As mentioned before the vacuum breaks going bad could be a cause. When I purchased my first 5'r I thought I was doing a great job of flushing the black tank until I purchased a clear elbow and found out how poorly I was doing it. If you do not flush the black tank sufficiently you will have odor problems. If you do not use sufficient water when flushing the bowl after using it you will have odor problems. Another possibility is that with leaving the grey water valve open you are not getting a good "flush" of food particles from the tank. If the previous owner did the same you may have "rotting" food odor coming up into the unit. Try some of the commercial tank cleaner they have for the grey tank and allow the tank to fill up a few times so it can get a good flush when it drains. Hope this helps!

06-05-2013, 10:13 AM
Thank you all for your ideas. We fixed the pressure problem by removing the elbow faucet and cleaning screen at RV wall. I will explore the suggestions about the odor. I know we have a broken valve cable on the black water and cannot keep the grey water line open because they share the main cleanout line. I flush out the black water first, then let the grey water out. It would be nice to be able to leave the grey water line open and only allow a build up every few days to aid flushing the black water, but until we get the valve fixed, we will make emptying the tanks a regular job. More later-got to go shopping for a truck, the old one cashed in its chips this week. :(

06-05-2013, 11:20 AM
One other possibility. Your black tank vent tube might be blocked or dropped down into the tank. That tube is supposed to vent the tank and stop buildup of gasses to prevent the odor from entering the trailer.

As to the grey line, you can leave it open. You can create a natural gas block by simply putting a hump in the sewer hose. That then is a "P" trap like the one under the sinks and shower. Those already should be blocking the entry of gasses into the rig as well.