I was awoken early this morning by my sump water level alarm going off. After some investigation, I believe that my sump discharge has frozen due to recent low temperatures.

I've verified that the pump is still functioning (Disconnecting the pump discharge in the house shows that it is moving water at high pressure. When connecting the pump discharge to the pipe that leads out of the house, water stops flowing.

My sump discharge is run under the basement foundation, then underground for about 300-400 feet, then pops out of a small mound on the side of a slope. When investigating the outlet this morning, I found it completely covered with snow, and no signs of water leaving the pipe.

I've tried running a snake from outside (Into the house, but it hits something hard (Assuming ice) about 1 - 2 feet in).

Specific Questions

  1. What is the typical way that a sump discharge is setup in freezing climates?
  2. What can I do in the short term (While ground is frozen) to fix this issue. (I currently have it running into my septic system, which I assume will mess that up in short order).
  3. What is the correct long term fix for this issue?

Sump discharge

Additional details if required

  1. Home was built in the last two years, and up until this point I would have said that I never have water in the sump.
  2. There are two pipes leaving the mound, the smaller of the two is the sump outlet, the larger is what I believe to be connected to the sump vent (Air vent out of the top of the sump pit) (But I have not verified this).
  3. Running electrical to this location (For heat tape or something similar) would be difficult (Especially with the frozen ground), due to the long distance from the house.
  • 2
    When you have a discharge like that, close to the surface, you need to ensure that the slope is high enough so that water doesn't sit in the pipe long enough to freeze.
    – jwh20
    Commented Dec 18, 2020 at 13:55
  • 1
    The drain snake is a good idea. Get one with a cutting bit. You can rent them from equipment rental yards. If that doesn't work, get a plumber with a water-jet to try clearing it that way. Careful not to let water back up into the sump pit while doing it. Also, try to identify your outside clean-out risers for this drain line. If you don't already have any (especially one near the house) plan on adding one as soon as weather permits. Commented Dec 18, 2020 at 14:08
  • Pouring a strong salt brine into the pipe might relieve the ice clog temporarily. A handful of water-softener salt into the sump periodically (depending on how often it runs) might also help short-term without killing your grass or pipe, but it might shorten the life of your pump a little. You should own a spare and keep it nearby anyway.
    – tgolisch
    Commented Dec 18, 2020 at 14:51

1 Answer 1


How is a sump discharge normally set up in freezing climates?

Short and wide, with plenty of slope, so that ice cannot build up in the bottom of the pipe. A 2" pipe to a 4" pipe with a fall to a gutter or ditch leading away from the house.

Alternatively, completely below frost line to a dry well.

What can I do in the short term

Buy 350-450 feet of garden hose (or enough more than you already own to get there) and run water in the far end of the sump pipe. You'll have to keep the water in the hose flowing so it does not freeze up on you, and get it back inside a warm area when you stop.

Depending upon your builder, you might also try complaining that the extravagant mess they built (a 300+ foot underground sump drain fully qualifies for that description, IMHO) isn't working right, and you'd appreciate some help from them correcting it. This might clear up which pipe is which, if nothing else - you don't want to waste a lot of effort on the wrong pipe.

Contact a plumber with a pipe-thawing rig - the modern ones involve a pump that drives heated water into a smaller pipe inserted in the frozen pipe, which can normally be done from inside the house where power is easy to come by. Given the absurd length of your setup a portable generator or large heavy-duty extension cord may be required to work from the other end as well.

The town I grew up in had a portable boiler for thawing frozen culverts by blowing steam into them, but I don't think such a thing is easily found for rental. If you get back to long, heavy extension cord or portable generator I guess you could try a wallpaper or cleaning steamer.

What is the correct long term fix for this issue?

Hard to be sure without knowing where the problem actually is. If it's just frozen at the outlet end, an immediate red flag is "the smaller pipe is the outlet" and I'd start with digging that up, going back in at least 10 feet and replacing the exposed end of the pipe with a larger diameter pipe, ensuring that it is sloped a minimum of 1/4" per foot. When burying that again, dig out 2 to 4 feet wide for 8-16 feet of pipe and lay a sheet or two of XPS insulation on top of the pipe, centered, which makes it act like it's buried deeper. Or apply more dirt and bury it deeper, which might mean building a retaining wall on the face where the pipe comes out. If the original pipe was not properly set, it may have lost slope with ground movement due to frost, causing water to pool and freeze.

If it's frozen in the middle of the run, that's a very expensive proposition to fix and is clearly your builder's fault for doing it wrong. Well, the whole mess is clearly your builder's fault for doing it wrong, it's only two years old.

There are electrical internal pipe thawing devices, usually intended for water supply lines, which can be placed and only powered as needed.

  • Unfortunately, I am not the one who had this house built (Bought it from some people that built it and never lived here), so I don't know who the builder is or how to contact them. Running a hose in the end is a great idea, and I'll be giving that a try right now (I think I've got just enough hose to reach it).
    – cyclops
    Commented Dec 18, 2020 at 14:58
  • 2
    Aside from making a large muddy mess, shoving a hose up the pipe and letting it run did the trick. After getting the hose lugged out there in freezing temps, it only took a few minutes before the ice had melted enough to break loose and out. Once spring rolls around, I'll likely get to digging to fix this correctly. Thanks!
    – cyclops
    Commented Dec 18, 2020 at 17:59

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