Teardrops n Tiny Travel Trailers

I've got a question or two about how to rig my grey water tank in a cargo trailer conversion.

Currently the shower drain goes directly through the floor of the trailer into empty space. I intend to mount a grey water tank under the trailer for the shower. Nothing else will go into the tank. I think I can go with a tank of up to 8" deep based on the ground clearance and axle depth.

My original thought was to install a Hepvo trap with the 90 degree elbow connector under the shower, then PVC that to the grey water tank inlet.

My concern is that the hepvo drain with the elbow is about 3.5" tall. Thus whenever an 8" deep tank is half full, that water is going to slosh back up the pip into the hepvo trap. I guess I could put a check valve downstream of the hepvo (between the hepvo and the tank).

Am I overthinking this? Will the shower --> elbow --> hepvo --> check valve --> grey tank work ok?

My other option is to have the grey tank directly under the shower and drain directly into it through the top of the tank. In this setup I would not be able to have a p-trap between the shower and the tank, nor could I have a checkvalve to prevent backsplash. I guess I could have a trap between the tank and the campground sewer but it seems like this has the potential to get smelly. I could have a larger tank in this scenario but I don't think its worth it.

Thanks!

Are you building the shower up off the floor and a raised up base where the plumbing is inside above trailer floor, or are you putting the shower directly on the floor where drain comes out below floor?

If not on a base above floor , then best rout may be to use a Sump Pump to pump it back up to the tank.

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I built the shower directly on the floor of the trailer, not on its own raised base. Probably should have thought through the piping more carefully before starting...

ETA: I dry fit the hepvo under the trailer and it looks like the bottom of the hepvo fitting is only about 3" below the shower drain. Not quite as bad. I'm thinking of just plumbing the hepvo to a ball valve to the grey tank. To prevent sloshing back up stream if I have to drive anywhere with the tank full, just crawl under the trailer and close the ball valve.

It looks like a check valve needs more pressure on it to work reliably and would be prone to failure/clogging.

Bit late here but I picked my shower up a few inches so I could dump into the top of the tank. I guess it’s to late for you to do that…


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Can you rise the out flow side of the P trap up higher with a short piece of pipe?

Can you rise the out flow side of the P trap up higher with a short piece of pipe?

Ok I just got it all in.

I was able to lower the grey tank by 1/2" by sandwiching I foam board insulation above it.

I was able to get a 1.5" pipe gasket for my no caulk drain. This let me go direct to a 1.5" male threaded adapter to the 90 degree hepvo connector. The good ol hacksaw let me cut some excess threads off the pvc mpt so it's pretty much immediately doing a 90 degree turn.

The hepvo then goes to a 1.5" pipe that heads into the grey tank. I drilled the hole as high up as possible. I left the 1.5" pipe long (sticking into the tank) to reduce backflow a bit. No check valve at the moment.

The 1.5" pipe runs basically flat or slightly uphill. It seems to drain ok but does pool some water at the 90 degree elbow. I could have lowered the inlet hole to get better drainage but that would cost me grey water tank capacity I think.

Hopefully it works out... Will have to readdress if the water pooling in the elbow causes any issues.

If I could do this again it would have been nice to have the shower up a few inches. Oops!