Should bilge pump line have a backflow valve?

[butchrobbins]

My bilge pump is a good ways away from the lines exit point on the boat-about 15 ft. When the pump operates, its pulls out the water, then when it quits a good bit returns to the bilge. Any ideas?

 

[Roger Long]

No, A check valve will slow down the back flow back but all the water in the hose will end up back in the bilge within a few hours. They are never 100% tight. Meanwhile, the check valve increase the chance of the line clogging. There is no good answer except to relocate the pump or thru hull to shorten the line.

I do have a check valve on my manual pump but it's right at the bottom in a fitting I can pull out of the hose to clear it if necessary. I can also stick my finger in. It's purpose is to make getting initial suction on the pump easier and as back up to the "must disassemble pump and other stuff to reach" inlet valve on the diaphram pump. It holds the water for a few hours but it eventually ends up back in the sump.

If your pump is located where you could get a short straight hose run up to just under the deck, you could put an anti siphon loop in which is good to have anyway. That would only cut your backflow about in half though.

 

[catsailor]

Check valves also increase the risk of freezing; even where you are the air temperature can drop below freezing, while the temperature of the bilge water never will.

Well, maybe not where you are, but it is a point to remember.

I'm jealous.

 

[Don S/V ILLusion]

Why can't you put a loop in the line closer to the pump?

In addition to minimizing backflow, it will preclude reverse siphoning.

 

[Maine Sail]

Simple

Simple answer, no. Also, second what Roger said...