Forum Discussion

tred0956's avatar
tred0956
Explorer
Jan 17, 2014

Plumbing questions: Moving P-Trap

I have a small Class C that is great for us except the kitchen area lacks storage, particularly drawers. Under the sink is a cupboard, but I want to install 3 sliding drawers in the cupboard. The p-trap for the sink drain is in the way for the top drawer, so:

1. Can I move the p-trap closer to the outside wall by putting a 90 degree elbow on the sink drain to run a drain pipe horizontally about 6 inches, then install the p-trap? I would like the horizontal drain pipe to be as close to the bottom of the sink as possible, to allow for clearance for the drawer. In other words, does the p-trap need to be directly under the sink drain?

2. The p-traps in my house use a slip joint to adjust for height, but the class C has everything glued. Any problem using a slip joint? I was thinking vibration might be the reason the RV is glued?

Thanks
  • Had about the same problem; just made the top drawer shorter. Used GOOD full extension ball bearing hardware, works great.

    Doug
  • I have seen a type of check valve being used in new RV construction instead of a P trap. I have no idea how well they work but it might be something to take a look at.
  • I agree with Scott... Our previous coach (Safari Simba DP) had slip joints in kitchen and bath... Never a problem. In fact, came in handy a couple of times when DW dropped an ear ring down the bath drain (not sure why she took out the screen).

    I too, will be moving my kitchen plumbing to the back was and then install a p-trap there, and... will be using slip joints.

    Ron
  • 1 Yes.
    2 No, every RV I've had used the appropriate slip joints and worked fine. Vibration is not an issue.
  • Yes you can move the "P" Trap, our 5er uses slip joint on all drain lines and we have never had a problem. I checked them a couple of times and they were all still tight. :)
  • My antique Class A has all household P trap plumbing. I have had to take it apart for other reasons, but it has never come apart on its own. The galley sinks have their trap out at the skin and it has never been a problem.

    We have a small coach too, so we fight for all the storage volume we can get.

    Matt
  • I have dual sinks in kitchen........both connect to one line that runs about 2' before there is a 'P' trap and then after the 'P' trap is a short stub pipe with an 'air admittance valve' on it before the drain line turns 90* and goes to waste tank.

    'P' trap doesn't need to be right at sink.
    Screw on fittings to sink drains and then glued joints on other fittings.....screwed joints on 'P' trap.
    Slip joints not good idea due to vibration/bouncing going on.
  • yes you can move it and use a slip joint. would recommend gluing though...due to vibration

About DIY Maintenance

RV projects you can tackle on your own with a few friendly pointers.4,352 PostsLatest Activity: Jan 23, 2025