P-trap for the sewer line.

I was thinking today (and this is generally a very dangerous process) and thought about why or why not to have a P-trap on the sewer hose. In the last campground I had to use 20' feet of sewer hose to reach the hook-up that was about 15' away so the extra hose would "pop" out of our black expandable hose support and create a sort of P-trap on its own. Now I am using 10' of hose to go 9' so there is no real excess hose. Would it help or hurt anything to make a 3" P-trap with plastic pipe and the bayonet fittings. It could be a hassle to disconnect, but we only do that a few times a year. I think it could help to keep odors out of the gray tanks since the valves are open all the time, but not sure since we can't really vent the line after the P-trap, but how much back pressure can a RV park sewer/septic system have?

Allan:

I know I am pretty new at this stuff. But when I started, I had an older gentleman take me under his wing when it was apparent that I was not doing the right things with my holding tanks. He says to me "son, what ever you do don't leave your drain valves open all the time." He says "if you do, you will have the nicest brown mountian growing in your sewer tank, kind of like Pike's peak" He also said "there are two reasons not to leave your other holding tanks open, one is critters gettin in and the other is not having any cleaner water to rinse things out after the "big dump" Really, that is what he said

I SEE NO REASON TO MAKE A P-TRAP WITH THE SEWER HOSE. ANY ODORS FROM THE SEWER TANK YOU ARE DUMPING INTO, WILL BE CONTAINED IN YOUR RV HOLDING TANKS.

He says to me "son, what ever you do don't leave your drain valves open all the time." He says "if you do, you will have the nicest brown mountian growing in your sewer tank, kind of like Pike's peak" HE IS CORRECT ON THE BLACK WATER TANK, ALWAYS KEEP IT CLOSED UNTIL YOU ARE READY TO DUMP IT. YOU NEED THE WATER IN THE TANK TO HELP DRAIN ALL THE HEAVY STUFF.

He also said "there are two reasons not to leave your other holding tanks open, one is critters gettin in and the other is not having any cleaner water to rinse things out after the "big dump" I DON'T THINK ANY CRITTERS WILL BE LIVING IN THE SEPTIC SYSTEM TANK YOU ARE DUMPING IN. AS TO CLEANER WATER TO FLUSH YOUR BLACK WATER TANK, YOU NEED TO HOOK UP A RINSE SYSTEM TO FLUSH YOUR BLACK WATER TANK. YOU WILL HAVE PLENTY WATER FROM THE RV PARK WATER LINES, OR YOU CAN USE YOUR OWN WATER FROM YOUR RV HOLDING TANKS.

Kenny:

My reference to "critters" was in jest. However my reference to the flush of the sewer line with the grey water tanks was not. I did fail to mention the fresh water flush of the "dark, dirty and smelly" tank after it was dumped. Sorry for the confusion.

sewers stink

the other reason to keep your valves closed until you dump your tanks ,, the smell will teach you to close them

Been RVing for close to thirty years, and fulltiming for more than 4...have always kept the grey tanks open and NEVER have had any smell back up into the coach. All the places that could allow that to occur have a trap to hold water that eliminates that issue...just like your house.

Now you can get a smell from the vent that goes out the roof. Sometimes it's too short, etc....there are aftermarket vents like the Cyclone that work wonders on stopping odors from this type of issue, instantly!...

We have 2 gray tanks. I leave them closed, it only takes a couple of minutes to drain. The galley tank hardly ever fills up, so that seldom needs to be drained before we leave the campground.
Occasionally I will leave the bathroom/washer tank open. Typically if there will be a couple of showers in a row and we are using the washing machine,

I have at times left both tanks open but kept a gate on the discharge to allow the full capacity of the two holding tanks to be merged. We do a t least one trip a year with no sewer hook ups.

I also leave water in the tanks for the trip home. Figure this sloshing around will help keep things loose in the tank.

I put in a sewer connection at the house and use an electric pump to finish the tank clean-out at home.

A stick house kitchen sink drain ties directly into the (black) sewer. It has the same type of trap that a camper has. All sewer odors are contained at each trap. Having multiple traps isn't necessary. Besides, your gray tanks are actually pretty nasty as well.

John