Bilge pump

[GeorgeTay]

My boat has a manual bilge pump permanently installed. I am planning to install an automatic electric pump in addition to the manual one. Can I tie into the drain hose of the manual pump without worrying about the water draining back into the bilge?

[pirateofcapeann]

You shouldn’t get any water back through the manual pump but the manual will pump back through the automatic, if it''s a centrifugal type like a Rule. You could put in a check valve close to the automatic pump but for the sake of safety it really should have its own through hull fitting and be a completely separate entity from the manual.

Pi

[kimberlite]

you shouldn''t put a check valve in the line of a bilge pump.
eric

[hamiam]

Eric is correct; you shouldn''t put a check valve in the line for the bilge pump as it increases the resistance and diminishes the flow rate. That being said, in many applications, if you dont have a check valve the water will backflow into the bilge as soon as the pump shuts off resulting in a pump that cycles continuously.

[kimberlite]

the reason you shouldn''t put a check valve in the line is that if the valve gets plugged your boat sinks. we have no check valves in any of the primary bilge pump lines. To eliminate the back flow i installes a small fully automatic rule pump (500 gph) with a check valve and its own through hull. this keeps the bilge dry.
eric