Why does water back up into the bathtub?

[Elektra]

We have a 44 ft, 1980 Gulfstar power cruiser and every day we have to turn on the pump in the head because of water in the bath tub. What causes this?

[ranger58sb]

Uhhhh....

Is it fresh water, gray water, salt water, or.... er... black water?

What kind of "pump in the head" are you turning on? Sump? Macerator? Or...?

-Chris

[Elektra]

Fresh water......pump has to be turned on when taking a shower..... Sink drain- bath and kitchen- backs up into tub....... Overboard discharge fitting appears to be higher than tub

[sailorboy1]

Sounds like it is just water draining back down the discharge line, is it a centrifugal pump or a diaphragm pump? If centrifugal replace it with a diaphragm and if it already is a diaphragm pump the valves are leaking (rebuilt or replace it).

[ranger58sb]

Maybe all those sources are draining into a sump that has a non-functional sump (bilge) pump inside? Perhaps the tub is the lowest receptacle that water can overflow into from a non-functioning sump?

-Chris

[Elektra]

Thks for your thoughts. Maybe faulty reasoning on my part, but I would expect salt water, not fresh, if the pump were leaking by. Drains are connected on the suction side of the pump.I traced the lines by hand, there is no sump between tub drain and hull discharge. Maybe there should be, and that is the problem.

[sailorboy1]

Originally Posted by Elektra

Thks for your thoughts. Maybe faulty reasoning on my part, but I would expect salt water, not fresh, if the pump were leaking by. Drains are connected on the suction side of the pump.I traced the lines by hand, there is no sump between tub drain and hull discharge. Maybe there should be, and that is the problem.

No, it's the fresh water in the line between the pump and the outlet flowing back down

[ranger58sb]

Originally Posted by Elektra

Thks for your thoughts. Maybe faulty reasoning on my part, but I would expect salt water, not fresh, if the pump were leaking by. Drains are connected on the suction side of the pump.I traced the lines by hand, there is no sump between tub drain and hull discharge. Maybe there should be, and that is the problem.

I was thinking of a situation where freshwater from the tub drain, shower drain, and both bath and kitchen sink drains, is routed to a sump. The sump pump (bilge pump) would then normally pump that fresh water overboard through a discharge hose.

You did say it's fresh water backing up into the tub... I don't see a source for salt water anywhere in a scenario like that.

If you traced the tub discharge hose directly to an overboard outlet... I'd think the only way you'd get back-up (and it would be raw water in this case), is if that outlet is submerged. And that'd be a bad thing

When you were tracing that line, is there anyway you could have made some kind of unseen jump from tub drain hose to overboard discharge hose? Perhaps in a space you couldn't see well? Feeling your way by hand?

-Chris

[Kenomac]

From your description, it sounds like there's a common grey water sump or gulper pumps servicing the shower and sink drains that should be turned on whenever you use any of those utilities. If you don't turn on the sink gulper pump, then it probably would just back up into the lowest point which is the shower.