Shower draining very slow

[conj]

I have been reading some threads on a similar issue with Galley sinks but appreciate an opinion on my issue.
We have a Shower midship which drains down into a Sump lower down in the bilge area which has an automatic submersible pump which then pumps it out to our grey water tank. The sink also drains into the same sump and tyhen pumped out.
problem is that it is very slow in draining from the shower tray into the sump and always leaves some water sitting in the shower.
I am thinking that maybe it needs some sort of breather to allow air into the line to help it drain.
the hose from the shower drain is about 22mm. The shower drain is below the waterline which i guess is not helping.
Any ideas would be appreciated.

[steve77]

I don’t see how an air vent will help. From your description, it sounds like at least two drain hoses are connected to the sump box, one from the shower and one from the sink. If that is correct, then when water drains from the shower, the air should just vent out of the sink drain. Likewise, when water drains from the sink, the displaced air will come out the shower drain. If I’m misunderstanding your installation, then there will be some other path for the sump box to vent, otherwise the sink would drain slowly also.

Showers have a history of clogging drains from hair, soap scum, and gunk. Have you tried cleaning the drain hose? Perhaps removing it from the sump box and using a garden hose to back flush the hose?

It won’t be a fun job. Cheers!

Steve

[conj]

Thanks Steve,
Yes, looking further there should be plenty of venting.
The way it has been designed previously, there is not a lot of angle for gravity to assist and the drain pipe is only about 20mm. So it has been suggested to put a bigger diameter drain tube and try and get more gravity working.

[NYSail]

I would assume there is a filter screen prior to the hoses dumping into the sump. Otherwise you would be fouling the pump with hair and food debris…….

Greg

[Rumrace]

Hair of ice take your pick. They were the culprits in my boats shower drain problems.
Daughters hairspray now I’m ranting.
My current boat was stored without the water system being winterized. Shower pump was fractured.
To clean the drain it’s just outside the wall in the main cabin floor. I can’t locate a vent to clean. But I replaced most of the water system. Pumps still run long after the rubber has go ridged and looses pressure. There are not many marine pumps worth a hoot or built better than a fish tank air pump.