Shower and sink drain system

When I first installed the sink drain I kept thinking to myself how a vented loop would be a nice addition to the drain. In my head I was imagining a way to also be able to drain the shower out the sink drain thru-hull. After a month of letting my mind wander through all kinds of ideas, I considered two options; a shower sump pump system or a switch operated drain pump. The shower sump would have been nice as it simply switches on automatically when there is enough water in the sump box. Unfortunately I don’t have enough room anywhere below the shower to install this big box so I opted for plan B. Mind you plan B is much more complicated but I gain a switch-activated drain for both the shower and the sink, complete with a vented loop.

An inline strainer for the shower tub drain in the bilge
An inline strainer for the shower tub drain in the bilge

One of the problems I faced is controlling debris that could easily clog and damage the electric impeller pump so I remedied this by adding a few inline strainers. One strainer is right at the drain but easily accessible so I can clean them out whenever I need but also a secondary strainer right at the pump with a finer screen just for backup to protect the impeller. Once I came up with enough of a plan I went to Second Wave to find the strainers and a new-used shower pump. I then went to Fisheries Supply to pick up the hose, clamps, terminal block, wire, some hose fittings and a ‘Y’ valve. I thought it might take several days but the whole project only took a couple of evenings.

A 'Y' valve to select shower tub or sink for mechanically draining grey water
A ‘Y’ valve to select shower tub or sink for mechanically draining grey water

I first installed the shower drain to the ‘Y’ valve and then plumbed the sink drain to the ‘Y’ valve. Then the hose went up to the final strainer attached to the pump, through the pump,  the vented loop and finally out to sea.

Sink and shower drain pump with vented loop (top left)
Sink and shower drain pump with vented loop (top left)

Contrary to the head pump, when I first tested the pump to see if it worked I could only hear the pump impeller spinning but there was no suction. This was alarming as I had already installed virtually everything and carefully measured and cut hoses to fit perfectly. I remembered from somewhere on the internet that some pumps need to be primed in order to work correctly so I easily removed the four mounting screws so I had better access to the pump. Then I disconnected the strainer quick disconnect and poured some water into the strainer until it began seeping out. After reconnecting and starting the pump I was in business. A couple of tests to ensure both shower and drain were draining as expected and I just needed to install the rocker switch to turn the unit on and off as needed. Now all of the head thru-hulls have vented loops and the sink and shower drains are finished.

Simple rocker switch for turning on the drain pump
Simple rocker switch for turning on the drain pump

I also dropped off the stainless freshwater holding tanks with Ballard Sheet Metal. They are likely who initially fabricated the tanks back in the mid-seventies and I’d really like to get another 30 years of use from them. New vinyl tanks of the same size and dimensions will cost me $500 with shipping so I’m hoping I get a quote back that is equal or less than new vinyl tanks. The original ones fit inside the bilge perfectly and have a water capacity of 80 gallons total. I can also add another twenty-gallon soft-tank in the forward birth and carry a hundred gallons total, which is plenty of water for weeks worth of adventure.

Custom made stainless steel holding tank for a Westsail 32
Custom made stainless steel holding tank for a Westsail 32
Underside of the Westsail 32 freshwater holding tank
Underside of the Westsail 32 freshwater holding tank
Rust and debris inside of a stainless steel freshwater holding tank
Rust and debris inside of a stainless steel freshwater holding tank

With the drain system out of the way and the stainless steel tanks getting evaluated I can relax and have my holiday. Besides, I felt the winter blast on the way home and I can smell snow in the mountains and I am due to some more skiing.

2 Replies to “Shower and sink drain system”

  1. Hi we are recently the new owners of a westsail 32! My question is about the shower pan. In the bottom of the pan is a drain that goes directly into the bilge. Our plan is not unlike your own, we wish to tie it in with the sink drain. But I’m wondering if the drain is a fitting? It to me looks like a bung hole in which it unscrews. Am I correct? I’ve been carefully trying to unscrew it but it doesn’t want to come, is it glued or does it not unscrew at all?? Thank you for your time. Sail on sailor.

    1. Hi Millee, no it does not have threads. I believe it is glued into place. I even went as far as to add a groove so I could unscrew like a flathead screw, but no dice. Just cut the hose and attach a new one. Also I added a cheap drain screen to keep debris from entering the drain. The screen trap installed near the compression base is very important. Both have kept the drain flowing nicely. Happy refitting!

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