Hi plumbing pros. A very wet Seattleite here, very stumped by my sump pump.

I have an 1920s home with a fully finished basement and an interior perimeter drain system, including a covered submersible sump pump system tucked away under tile/slab and behind my clothes dryer. All done by previous owners about 15 years ago.

Here’s what the sump pit looked like when opened after some heavy-ish around Christmas. Note that there wasn’t a check valve installed. Also note the short discharge pipe. I assume the discharge pipe ties into the combined sewer drain along with my bathroom fixtures since it doesn’t appear to discharge anywhere outside.

Sump pit with old pump: [imgur.com]

We’ve had more rain here in Seattle over the last couple weeks with more in the forecast, so I had a plumber replace the old (10+ years) Zoeller pump (unknown model) with a new Zoeller 1/2 horsepower model plus a check valve (new pump and check valve not pictured).

Well the rains kept coming on cue and the new pump has been cycling often (every few minutes during and right after heavy rain) and a few times per hour (even days after heavy rain). It cycles for only about 5-6 seconds at a time, which I assume is at least partly a function of the small-ish pit.

After the quick pump cycle, I hear what sounds like a slight “whoosh” of the check valve closing followed by a loud, long, and two-parter “pouring” noise, where it sounds like a substantial amount of water is falling back into the pit.

Loud pouring noise video taken above the closed pit (sound on): [youtu.be]

I unfortunately don’t have the ability to re-open the covered pit at this time to get a better video. Sorry about that.

My questions:

1) is this pouring back sound normal? Especially since I now have a check valve and since the water doesn’t have much vertical distance to travel to the discharge pipe anyway? I can’t seem to find any videos online that show this and it’s crazy loud. Improper install? Airlock? Blocked drainpipe?

2) Why would the pit be filling up with water so quickly/the sump cycling so much if I don’t hear water flowing in from the white inlet pipes? Wouldn’t I hear the same pouring water noise? Is it common to also drill holes in the bottom of a sump pit for ground water to seep upwards into? I think I see some holes in the side of the pit in the photo above, for example. Or perhaps the pump is simply not be clearing and cycling the same water over and over again?

The best part is this pump is one floor below where my head rests on my pillow at night. And this sucker us been hard at work, humming and pouring for several days. I’ll need to break into the good scotch to get some sleep tonight...

Any ideas?



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If the sump isn't vented(it unofficially was before the check valve installation) the pump might be creating a vacuum and sucking water in. You need to remove the lid and observe what's happening. If it doesn't do it with the lid removed, a vacuum is being created and the sump needs a vent.

Thanks. It’s not perfectly sealed like a sewage pump. Just the lid, which is itself loosely screwed on/without a perfectly straight seal or rubber gasket or anything.

Plus, there’s the small hole for power cord, which also isn’t airtight.

Think that’s enough of a seal to cause what you’re describing? And would a nuclear option be to revert to having no check valve? If a weep hole was drilled in the pipe, I assume that would need to be plugged?

Appreciate the response! Total newb here trying to keep my house from floating away.

put a wedge or block under the lid to keep it open about 1"

if the noise goes away then you know it was a 'vacuum lock' and you need a vent


since it is a sump (NOT an ejector) and if there is no smell you 'could' merely drill a 2" hole in the lid for a vent

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Thanks - I’ll give this a try and report back.

I also sent this video to Zoeller to see if they respond and comment on whether or not they think it’s normal.

Update: the plot thickens!

Opened up the pit. Here’s what it looks like:

[imgur.com]

The brand new 1/2 pump is working well, albeit short cycling more than is ideal at the moment. The check valve (vertical, green) seems to be doing its job.

The pit is filling up with water fast after the record rains we just experienced here in Seattle, the vast majority of which is coming from the small holes drilled in the basin (a couple are circled in blue, but they are scattered throughout and there are several below the water line). Draining the pit completely reveals water rushing in fast from the lowest drilled holes, which are well below my 100 year old, thin slab, complete with zero gravel layer or vapor barrier, or anything resembling a building code.

Right now the pump is going off about every two minutes. The ground is saturated far above normal levels and the water table is simply very high. I know there is some debate around the concept drilling holes in the basin altogether. My setup may be a bit aggressive and capturing more water than is really needed. A much smaller amount of water is trickling in from one of the white inlet pipes (the one that is not circled).

I confirmed that this discharge is tied into the combined sewer. I unscrewed the cleanout in my backyard, which is on the other side of the wall from the sump pit in my laundry room, at ground level, not 10 feet away. I put my ear to it and could hear some water gurgling down below when the pump cycled. The side sewer has been cleared and lined recently.

Here’s the catch — and the source of the pouring noise!

The OTHER white inlet pipe (circled in red) is the culprit. Unlike inlet pipe #1, I’m not seeing a trickle of water coming from this pipe as the pit fills up, at least at the current flow rate. But, as soon as the pump cycles, a small amount of water (maybe 1/2 to 3/4 cups or so) pours out of this inlet pipe and into the pit immediately after.

Huh?

This is makes me worried that there must be a break in the 1.5 inch discharge line (which also happens to buried under concrete, tile, and drywall). My current hypothesis is that there is a fitting that is loose somewhere despite it being only about 15 years old. And when the pump cycles, sending water through the discharge line, some amount escapes only to be caught immediately by the nearby perforated white inlet pipe. My hope is that 90% or more of the water is making it all the way from my sump basin to the sewer and only a small amount is escaping. However I can imagine some water is lost in the process and going exactly where it shouldn’t be going.

I think I will need to call someone with a specialty, very small scope camera, peek in the discharge line, and see what we can see. Any sort of fix is going to be very destructive (expensive) to the finished basement. I assume you can’t just line a little 1.5 inch pipe. It may ultimately not be worth it if we can also confirm that most water is going to the sewer (will require a proper scope of that too) and if I’m not experiencing major symptoms of the lost water.

What do you all think of this hypothesis? Could there be another explanation that I’m not thinking of?

(As an aside, hundreds of thousands of people in Western Washington lost power in the combined record winds and rains last night. My own power was flickering all night. Power went out two blocks away. I was on pins and needles wondering if my sump pump, which was cycling every two minutes, was about to stop at any moment and flood my newly refinished basement. Time to look into back up options, even though I am working with very little space behind a clothes dryer!)

You could put food coloring in the sump, capture the inrushing water and to see if it has coloring in it. Is abandoning the 1 1/2" and running a new pipe, up and out the wall, an option?

I can give that a shot! Although I can’t imagine what other water this would be.

Abandoning isn’t a practical option. I’d have to break through a chunk of house.

Is there any world in which they would’ve also tied the inlet pipe into the sewer directly VS funneling to the pit? I can’t imagine why/I might be grasping at straws here.

If it is a leak or busted fitting, I don’t suppose you could line a small little pipe like this a la my side sewer VS breaking into the wall/concrete/tile of the finished bathroom to replace the discharge pipe where it’s currently located?

I think that pipe should have a camera inspection to find the exact cause and location of the leak. There are small diameter lining services/equipment available. Once the cause is located, next would be finding the most cost efficient repair method, lining vs digging vs rerouting.
[www.nuflowtechnologies.com]

Thank you!



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