No fall in my plumbing drains. Need a pumping solution

Here’s the situation, my plumbing drains (shower and sink) exit my bus at the same height (possibly a little lower) than where my greywater tank inlet is. The problem is unless we park on a significant hill creating ‘fall’ in the system… our drains back up.

I imagine the soltion to be adding some sort of inline pump to our drains to essentially pump the grey water uphill to our grey water tank. But im stumped. Any advice would be great thanks.

Greetings & Welcome!

Geez… Is your sink on the floor too?

I have seen builds that utilize a portable tank under the vehicle. Maybe that would be the easiest solution…


"Failures are merely a learning oportunity." ~ Rubber Tramp

Lol. No my sink is not on the floor. But I have one 1 1/2" inlet to my grey water tank so I’d like to ultimately run both appliances through the same drain this the reason for joining them upstream.

Unfortunately to he portable tank deal just won’t work for my situation.

Thanks for your response.

:airplane: :seat: :jeans:

On the boats where the shower and sink drains are below the waterline, we use a system that utilities a bilge pump in a box which is activated with a float switch. For research purposes, it is called a shower sump and you can likely find examples of them in boat owner forums.

The float level of the switch is higher than the suction base of the pump so as to ensure that only water is pumped and not air.

When the shower is on the drain water enters the box and the level increases which in turn raises the float switch and closes the circuit and the pump discharges the grey water overboard.

The box is completely sealed and access to the pump for cleaning etc (this will need to be done fairly often because of hair and soap scum build up etc) and is usually by means of a screw on lid made of plexiglass with a rubber gasket.

I hope this helps.

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