brunnhilde's slimming program - waste water discharge pipe

Face it, Brunnhilde has gotten a bit porky since coming to USA. I am helping her on a slimming program to return to her natural self. Like Mr. Shaw's drama I would soon make a lady out of her when we are through.

Now the cassette toilet conversion project is complete and the sink and faucet deficiencies are sorted out, the next project is to ditch the honking 3" diameter waste water discharge pipe more like a phallic symbol.

The piping from the grey water tanks is 1.5 inch ID so the logical choice is to reduce it to that diameter pipe. To design a system compatible with US dump facilities and ideally can be used in EU countries and my design goals I list the following considerations:

• the waste water discharge pipe shall provide easy access and connection with a discharge hose
• a hose system that takes up amount of storage space with at least 10 feet length, it must be flexible and easy to keep clean
• the camper end of the hose must have a quick connect with secure water seal without the need of loose gasket or o-ring
• the hose end should be rigid enough to be crush resistant and shall be easy to keep in place at the dump tank input port which typically has a cast iron lid

I cam up with a preliminary rough plan which can be refined as I research suitable material and parts:

I will remove the 3" discharge pipe by cutting it at the 1.5-inch ABS pipe from the grey tank. I will then fabricate a 1.5 ID ABS pipe discharge pipe with 1.5-inch ABS household plumbing fittings. The smaller diameter discharge pipe will be supported by the two existing hangers but with smaller diameter clamps. The black color pipe just blend in with the dark color of the vehicle underside as well as the pavement.

For the discharge hose I selected the 1.5-inch or 1.25-inch hose used in swimming pool vacuum. They are flexible as well as designed to resist chemicals. They are also crush proof and compact to carry.

I did some search on ABS plumbing fittings and the joint that I like is the one used on p-traps. It requires no gasket or o-ring and forms a very secure seal with just hand tighten of the joint.

However with my search this joint is only used on p-traps. In a pinch I can make the p-trap work by keeping the bend horizontal.

I then search on unions to see what they use. Apparently some unions used for swimming pool system may have similar joint. I cannot tell by reading the description and there is no image depicting when the union is disassembled.


union used in swimming pool in white ABS

there is also one with the built in ball valve which i can eliminate the failure prone cable-operated gate valve - this is looking promising