Why Does My Sump Pump Run Constantly?

411 plumb A sump pump constantly running can be a good thing or, a bad thing depending on whether it is pumping water. Of course even if it is pumping water, constantly running is an indicator that the pump capacity is very closely matched to the flow of the ground water, and that should be a cause for concern. A slight increase in ground water flowing into the pit may overwhelm the pump and flood your basement or, a pump failure will as well. There are a few things you should check when you find a sump pump running constantly just to be sure that you are not close to being flooded.

One of the first checks that should be made on a constantly running sump pump is if the pump is indeed pumping water and operating close to its full capacity. There are sometimes things that can happen which can affect the pumping ability of a sump pump and it should be checked for proper operation. Often sand and silt flows into a sump pit carried in by the water, which then erodes the impeller vanes as it is pumped out with the water causing the pump to become ineffective. Sometimes impellers are made out of a metal that may corrode, which results in an impeller that has no vanes left to pump the water. A discharge pipe or hose can become clogged, broken underground or, in cold areas if it doesn’t drain dry after each pump cycle can freeze. When the discharge is blocked the sump pump deadheads and runs constantly usually with the water in the pit becoming warm or, even hot. Another common cause is the discharge pipe or hose coming loose from the pump in this case you will see water circulating in the pit. One of the requirements for installing a sump pump with many pumps is a 3/16” hole to be drilled in the discharge pipe a short distance above the pump before the check valve. When a sump pump pit goes dry during a period of drought it may dry out. When the pit refills with water the hole is needed to allow the air to get out of the pump allowing the pump to prime. If the pump is air bound because of water above the check valve holding air in the pump, water cannot reach the impeller so the pump will run constantly without pumping. In any case if you can see the water discharging from the pump it is a good indicator that the pump is operating properly.

If your sump pump is constantly running and you have found that the pump is pumping correctly you next should consider the ground water level, the ground water volume, and the pumping capacity. Sometimes the best thing to do is add pumping capacity and or, back up pumps, while other times simply raising the pump a few inches can allow the ground water to reach its own level without constant pumping being needed. During the dry period of the year is a good time to play with the pump level if the pump is running constantly even then. Shut off the pump and see how high the water gets in the pit. Naturally if the water comes up and is going to overflow into the basement, you have a very high water level and the pump is needed. However, frequently the water will rise to a certain level in the pit without flooding the basement or even reaching the bottom of the concrete slab. If the water level stops rising you should consider raising the level at which the pump turns on and allow the water level to remain at that level in the pit with the pump only turning on when it gets higher. You can also stretch this check into wetter periods of the year to fine tune the point at which the pump turns on. Sometimes people find that the pump was just set too deep into the water table causing it to pump water that didn’t really need to be pumped and when the pump was raised the running became infrequent and almost never ran constantly.

If your pump is running constantly and any time the pump is shut off the pit overflows then additional capacity and backup is something that you should strongly consider. The volume of ground water is too closely matched to your pumping capacity and any increase in ground water volume or, a pump failure as virtually guaranteed to cause a flooded basement. Back up pumps and power is strongly recommended, and the capacity of the back up pumping should be high enough to meet your needs.

You may want to consider other basement water proofing options as well such as curtain drains, regrading your property to divert water away from your home and installing drains for gutters and storm water to carry the water away from your home. Passive measures are always better than relying on a pump to get rid of the water.

Damage from a flooded basement can be very costly especially when appliances such as boilers, furnaces, HVAC air handlers, and water heaters can be severely damaged and often require replacement from flooding. The costs of using the services of an expert are trivial when you consider the cost of damage from flooding.

Posted in plumbing questions, Sump Pumps & Sewage Ejectors Tagged with:
104 comments on “Why Does My Sump Pump Run Constantly?
  1. paul murray says:

    I wondered about the water softener discharge going into the pit. I had read that was not good for the sump pump. From what I can gather, most water softeners can pump 6 to 8′ upward. I’ll have a different plumber than the original to take a look at it. It is always worth it to get a second opinion.

    I like the idea of the variable switch. Would the Switch-mate work with the Big dog sump pump with battery back-up because the battery back up pump would go off and run off the battery. From previous posts I realize you’re not fond of that sump pump but it’s what I got and is only a year old. I live in relatively new development and the power has not gone off once in that past year. When I’ve asked neighbors how often do you lose power they give me a blank stare.

    • Redwood says:

      Hi Paul,
      The switch works as is on any pump that plugs directly into a 120-VAC power using a NEMA 5-15P configured plug.
      If the float switch is configured another way you would have to cut the plug off and wire in the 2 leads for the switch.
      As for the Big Dog Pump it’s what you have, it’s working, and it’s paid for.
      Upgrading can always be done when you need to replace it.
      My recommendation would be the Zoeller BN-53 with the Zoeller 10-0034 Switch-Mate Variable Level Float Switch sold above.

    • Redwood says:

      Hi Paul,
      Thanks for sending the e-mail with the pictures, I’ve included it below.


      I attached a few pictures of the pipe configuration. The Liberty pump pipe is to the right and the Big dog to the left. I have a 1/2 basement and 1/2 crawlspace so you are seeing the pipes come together and exit the crawlspace (they exit maybe 60′ from the house). Unfortunately much of it cannot be seen due to insulation. I think the gushing water sound is likely due to the configuration and fact that the insulation is not between the pipe and overlying floor. I might be able to move the insulation between the two or do something else to dampen the noise. I’ll have to look at it closer.

      Sump Pump Piping

      I failed to mention that they put the Liberty pump on about 5 inches of concrete block and the Big Dog on about 6 inches of concrete block so actually the Liberty has been the only one running (about every 3 minutes or so lately) without the Big Dog running at all. The liberty seems to come on at about 10.5 – 11 inches of water. About 4 hours ago I shut off the liberty pump and the water has stopped at around 12 inches in both pits with neither going off. The water is right at the bottom of the float cage of the Big Dog so I’m guessing it would have to come up an inch or so before activating. I’ve heard of people claiming that their pumps go off every 10 or 15 minutes or so. In my experience, mine have always went off in the 2.5 to 6-7 minute range or not at all. I think I’ll end up getting one of those variable float switches for the liberty pump so it is more in line with the Big Dog one.

      Liberty Sump Pump Installation

      I emailed my contractor about the water softener issue. The liberty pump is really looking corroded (you can probably see in the picture). I live in Pennsylvania. I really wonder if it passes code or not. Anyway, I’m going to see if the discharge can be sent to my septic tank/fields. I Googled the issue and it seems like that it shouldn’t be a problem to have the discharge go to the septic. Do you know of any reason why they would have wanted it sent to the sump pit?

      Thanks again for everything, especially bringing the softener discharge to my attention.

      Thanks, Paul

      The sump pump pipes look like they were correctly installed, in one of the other pictures that I didn’t include I saw the check valve was immediately above the pit in the proper location. The pipes drain by gravity from immediately above the pit where it turns and runs across the basement/crawlspace ceiling which is proper, so there is a lot of empty pipe which will fill creating noise when the pump kicks on. I suspect most of the noise is created at the point where the line turns downward then turns out through the wall. I believe the best option is probably to insulate the pipes with a pre-slit foam pipe insulation, which you can slide over the pipes and then tape closed. The insulation will help deaden the sound.

      Looking at the picture of the pump in the pit I see a lot of room for changing the height the pump turns on at to increase the run time when the pump is needed, and allowing the ground water in the area to rise slightly higher decreasing the times the pump the pump is needed. If you are able to set the run level above the 12″ level where the water doesn’t seem to rise the pump will probably run very seldom. The variable level float switch will accomplish this quite easily, not running at all will certainly deaden the noise.

      In years past softener discharge to septic systems wasn’t recommended because of a reaction to the concrete used in the tanks, however, today’s tanks should be constructed with a different mix that is resistant to the effects of the salt brine. There are two camps on the discharge with claims on each side that the brine discharge into the leaching fields are harmful or, beneficial. I’m not knowledgeable on the subject to stake a claim either way. In Connecticut where I live discharging the softener into a septic system is prohibited yet in other states it is allowed. I do not know the laws in your location so you would have to research that and comply with whatever they allow.

      Sounds like you are on track,

  2. Paul says:

    In follow-up:

    This Thanksgiving I cleaned out the sump pit and ended up lowering the 1/3 HP Liberty pump back to the bottom of the pit (it was on 3 blocks, see previous picture). I cable clamped the Liberty float like you suggested and added a tethered piggy back type float this Spring. That worked very well. I was able to pump out about 9″ of water per cycle instead of about 4″ before. Now that I have lowered the pump it is currently activating at about the 16″ level in the pit and running till about 3 1/2″. Tonight, I timed this and it takes about 30 seconds to displace that much water. From what I can gather it is usually a good thing to not have your sump pump “short cycle” and that you want a fairly long run time (less cycling, longer life, don’t have to hear it so much, etc.)

    Is this too much of a good thing? The water table is just reaching the 16″ level about now so I am starting the sump pump season (after 4 months of silence). Personally I would rather hear it less often. I did insulate the pipes which helped somewhat with the noise.

    • Redwood says:

      Hi Paul,
      It sounds like you have made some progress, I would have the pump at least on 1 thin block or piece of slate, so you don’t suck in any debris off the sump bottom into the pump. You could probably get even a little lower than 3 1/2″ on where the pump shuts off at the end of the cycle as well. Play it by ear and make sure it shuts off before drawing air. As far as the upper level where it kicks on as long as you are below where tiles come into the pit and at a level where water isn’t a problem in the basement or, crawlspace you are in good shape. Depending on how well the sump is sealed, with a fully sealed sump only draining ground water to a level where the tiles are, and a leaking sump pit draining the ground water in a cone shaped area surrounding the pit to the lowest leak in the pit you’ll have variations with how much ground water is under the basement or, crawlspace floor. The width and steepness of the cone depends on the drainage ability of the soil as well.

      The drainage cone extending towards a second sump pump adds to the mix that you’ll have to work towards synchronizing the water levels where they run so that both pumps are sharing the work load vs. one doing all the work. You are on track with what you are doing and the tethered float switch gives you the added control where you can observe the operation throughout several seasons tweaking the settings as you go until you become satisfied with them. The longer run time and longer off time is going to reward you with longer pump life.

      Nice Job So Far,

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