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Question DetailsAsked on 2/25/2018

Sump pump pit doesnt stop getting water for at least 1 week after it rains.

Sump pump, pumps into drain literally every minute or so. I thought it was the slope but my neighbor doesnt have this problem. Water doesn't stop entering, I tried redirecting the water to the ground away from the house but that just created a pool in the yard and the water still came in. I checked the sewer in the front of the house and I don't hear any water. Is there anything I can do to stop it from coming in?

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Unless pretty level geologic beds and pretty flat land (you mentioned a slope), one would not normally expect a neighbor's system to behave the same as yours - that would normally only be true in flat-lying geology and river floodplains and such.

And an important fact - since you say it drains frequently for about a week after a rain, but presumably tapers off to maybe once every 15-60 minutes after that, sounds like precipiation is the source - REGARDLESS of the other possibilities like leaking pipe I talked about below before I reread your questions and keyed in on the above fact. Sorry.

First, check that the sump pump water is actually getting out of the discharge pipe - not largely or totally just draining back down into the pit as soon as the pump turns off. Might be the backflow preventer flappear valve has stuck open and the pump is just pumping the water out of the pit into the discharge line, then the pump shuts off because the water in the pit is now below the switch setting level for the pump to be on, so then the water flows back out of the discharge line and the pump (be sure it is powered off if you stick your hand down in there to check for backflow out the bottom of it) into the pit again. You could also put some food coloring in the pit and immediately (before it has a chnce to diffuse into the underdrain pipes) turn the pump on and run it till the pit is down to the intake level of the pump, then see if the water coming back into the pit is the same brightly colored water you made or just very faintly colored from the bit left in the pit and what backed slightly into the underdrains.

Also - if you run the pump till it is going dry, you may (or maybe not depending on configuration) be able to see the outlets of the underdrain pipes into the sump. You may have to shut pump of and bail some by hand to get the ewater level below the pipe outlet levels. If you bail it out that far, see if water is continuously (after the initial standing water draining out of the pipes themselves) flowing from all of them or maybe mostly just one - that might tell you if it is a continuous inflow (as you keep bailing) and also if it is coming in primarily from one side of the house.

Another thing you can do, once you have ruled out the water just draining back out of the discharge piping back into the well, but do NOT let water level rise to the motor part of the sump pump (usully no problem - usually well above slab). Of course can't do this if you have anything on the concrete other than maybe a concrete paint - could wet wood or laminate or sheet flooring or carpet, for instance. But if plain concrete slab, try turning the power off to the sump pump after it has pumped the sump down once - then watch as it fills the sump up. If it fills quickly initially but then slows dramatically or basically comes to a stable level rather than continuing to nearly the top of slab (when you would power it up again), then case 1) below. If keeps filling the sump so it looks like it is going to overflow the sump at a fairly constant fill rate, then you may have a significant inflow and need to investigate that - because basically any power failure of more than a minute or few is going to cause an overflow event. This is case 2) below.

Case 1) if pumping the sump out results in rapid initial refill but then rapidly slowing after it comes up a bit (say a bit above the normal fill level where the pump kicks on), then it is likely your backflow preventer (sometimes in pump, sometimes put in the pipe shortly downflow from the pump) is letting water flow back into the sump from the discharge pipe.

For instance, if you have an 8' vertical 2" diameter discharge pipe from the pump and maybe 0-30' of pipe along the joists or such to the outdoors discharge point, that could hold as much as 1.5 to 7.5 gallons, roughly, depending on the length of run. The sump, if 8-10 diameter, would hold about 2.5-4 gallons per foot of depth not counting the volume taken up by the pump itself - and generally holds about 1 foot of water between turn-on and turn-off levels.

So - if a significant amount of backflow from the discharge pipe is occurring, the pump could be pumping out the same volume of maybe a few to 5 gallons of water each time, which then flows back into the sump and the connecting drain pipes and gravel under the slab - pumping much the same water every minute or so, with maybe very little new water coming in. A proper sump discharge line backflow preventer located right above the pump would stop all the backflow except what is in the pump itself. Actually, you can probably just listen at the pipe and hear if there is backflow occurring in the discharge pipe.

Case 2) if the sump refills and would fill the sump completely up quickly, then look, and listen around with stethoscope, for any water source. Surface water, groundwater, blocked french drain, overfilled septic tank or saturated leach field if you have them. Of course, whether this varies depending on precipitation or snowmelt would also give you a clue as to the source - in rereading I see you relate this to rainfall, so if it tapers off to a very low pumping frequency during rain-free periods or the dry season, that tells you it is not a leaking pipe situation or backflow preventer failure.

if psossibly NOT rain-related, you can also turn off all water in the house (including any circulating pumps, furnace, A/C, fans, etc) and listen at the pipes for any rushing or hissing sound which might be indicative of a leak. Also, if you have a water meter, see if it is recording use with all water usage points turned off. May be a simple as a leaking pipe outside or a frozen and broken outside faucet, for example.

Another thing you can do, though would probably take several hours of water shutoff, is (you or plumber or utility) shut off the water supply to the house entirely - at outside shutoff near street- then see if the inflow reduces and the sump pump activity slows down. If so, that would be a pretty good indication of a water pipe leak or a pipe running continuously.


Two other possibilities - the outlet is mostly blocked by debris or ice, so only a little water is actually escaping the discharge pipe each cycle. Or the discharge pipe is going down into a drain which is full becaue of blockage or improper slope or whatever, and does not have an air break where it enter the drain s it should - so it pumps the water out, then because ofthe height of the water column between pump and discharge line (normally hung from overhead joists) siphons it right back in again and back to the sump - largely refilling it. Backflow preventer will also prevent this.

Though the drain line should go to maximum height immediately (say to ceiling), then slope downhill from there to the outlet so it drain clean every time - reducing chance of algae buildup or freezing of the discharge line.

One other thought - you do not want the pump down in the bottom 3-4 inches of the sump or it will pick up silt and such (which should be bailed out by hand every few years to extend pump life) - but if it is set too high it is not signficantly drawing down the water level under the salb when it pumps out, so it might be short-cycling for that reason - only pumping out a small amount of water but not draining out the drain lines under the slab and a lot of the water around them under the slab, so it does not take much time for that volume to refill with water and kick the pump on again.

Now - after rereading the part about being rainfall related, it could be you have roof runoff and/or surface water, and/or possibly groundwater, basically making a swimming pool of your house excavation and backfill. Proper gutters with downspouts and low-permeability drainage surfaces away from the house can handle roof runoff. Proper low-permeability soil or asphalt or concrete or such around the house, sloping away from the house at least 1/4" or two per foot (preferably if compacted soil surface more like 1/2" per foot slope or more for at least 3-6 feet from the house depending on native soil permeability (3-4 feet OK in clays or impermeable silts, more like 6-10 feet in sands and gravels and talus slopes and such) can keep the roof runoff from filling in around the foundation and coming out your basement underslab drain pipes into the sump.

If you have a perimeter french drain around the outside of the foundation (or you may need one if surface water control will not solve the problem), check if it is free-draining. it may beplugged or backed up or outlet frozen, preventing it from intercepting the underground seepage feeding the sump.

One other possibility, much harder to fix in many cases - someone, somewhere got the bright idea, which has spread widely, that it was a good idea ot connect exterior french drains with the interior underslab system. Sometimes this was done with weep holes through the base of the foundation at the top of the strip footer (so appearing inside the basement at just above slab level), sometimes through or underneath the strip footer where it is hard to get at. This is just simply a dumb idea - letting outside water get inside, and can overwhelm an underslab and sump pump system, not to mention filling the basement up much quicker during power losses or failulres at the sump pump. If these weep holes are visible, AND you have a functioning french drain buried near foundation base level outside, they can be blocked with hydraulic cement to cut off that inflow. If the slab was cut to installthem and a perim,eter drain pipe, that may have to be cut up and redone without them - might take a run with a sewear camera into the french drain and the underslab drain pipes to see if that is the case.

If blocking them off, and there is NOT a french drain outside, a Structural or Geotechnical Engineer would have to be involved, to determine if the foundation can take the extra load of a higher wter level outside. Also, without a function french drain outside, blocking those off will cause leaks through the foundation wall if it is not truly waterproof with waterproofing on the outside - a pretty substantial job to be done after the fact because they have to dig down to the bottom of the foundation (assuming it is intact enough to allow that) to do the waterproofing - at which time it makes sense to put in a french drain there at the same time. LOTS of previous questions with answers on french drain and underdrain systems can be found in the Home > Basement Waterproofing link, under Browse Projects, at lower left.

If unable to handle this investigation and/or any repairs yourself - Plumber can handle backflow preventer installation and any modification of setting height or line slope. Otherwise, a Basement Waterproofing contractor would probably be your best bet. But as you describe it, and as many of the answers in the Home > Basement Waterproofing link at lower left say, I would start with finding any accumulation points around the foundation for roof runoff or surface runoff, get drainage established to get and keep that water away from the foundation so the fill around the foundation does not become a bathtub full or water, and make sure any outside-the-foundation french drain is working and draining to a free surface well away from the house. Then if that does not solve it, you may need to move on to other measures like a french drain outside the foundation or blocking off any weepholes that were put in the foundation.

Possible inflow sources - aside from any recent rains or snowmelt events:

1) water pipe leak

2) water from neighbor's runoff, septic, or a pipe leak

3) some modification has been made to surface drainage so you are getting water to the house which did not used to

4) you have a french drain around the foundation or out in the yard which is clogged or the outlet (or entire pipe if colder than usual winter) is frozen up

5) you have an interconnection, as detailed above, between outside the foundation and the underdrain system

6) you have a septic system overfilling the tank, or oversaturtating the leach field (due to rain, freezing, or system is getting old and not draining right) causing backflow to the house through the soil. (Usually the sump and discharge water would be pretty ripe and blackish or grayish if this werew the case over a long period).

Here is a similar question with answer which might help too -

Answered 8 months ago by LCD

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