Water leaking out backwash line


New member
Nov 26, 2013
Hi all,

I have a salt water pool with a DE filter. Water is leaking into the backwash line in filter mode, and exiting at the wastewater pipe at the front of my house.

My pool guy's solution is to "clean the filter" and to install a "ball valve" at the front of the house, where the water is trickling out.

Filter is probably 10 yrs old, time to replace it?

Last edited:


TFP Expert
Mar 2, 2011
The filter is super old. That's why they don't want to work on it. Probably time for a new filter.

It's like working on a 40 year old car. You can make it work, but it's not worth it unless you really like the car.


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
It's not a simple spider gasket repair on that filter. The backwash valve is inside the base. I have the same kind of filter and mine developed a drip. For a while, just jiggling the lever would eventually stop it, but then it wouldn't. So I unscrewed the backwash hose barb and screwed a pipe plug in to dry up the leak while I researched things. It looks like a major undertaking -- cutting pipes to move the base for access for starters. And then there's the risk that once I've ordered the parts, cut the pipes, and disassembled it all, I'd discover some mating surface was chewed up beyond smoothing and the whole filter will need replacing. Your pool guy has probably reached the same conclusion

The temporary fix has been in place now for about a year and a half, if it's any help to you.

My pool is ripe for replastering and I figured I'd upgrade the filter and pump then. But then everything got all scrambled with shutdowns, so maybe next year.


Jan 3, 2019
Chula Vista
I have the same issue, dripping from the backwash outlet. I have a Pentair SMBW 4060 and I replaced a broken o-ring on the rotor value (Pentair 071426 Collar and Rotor Union O-Ring Replacement). This could work for you but did not stop the dripping for me. What should I try next? How about replacing 071720 Seal BW valve rotor tapered? Would it hurt the filter to use a winter plug to slow or stop the dripping?