Preventing sump pump discharge lines from freezing?

Post 5.

Why not just install some heat tape if freezing is a problem, its thermostatically controlled so it wont run all day either.


I have to say, I live in new england, and my sump line has never frozen, I have pitch on it and it runs a good 10' outdoors in 1 1/2" pipe.

When I lived in Bangor, ME we had a sump pump that needed to run periodically in the winter months. The key to keeping the line from freezing is to use a larger diameter, smooth, rigid pipe, such as PVC, and making sure it drains completely (properly pitched with no low spots). Don't use that ribbed, flexy discharge hose outside; water collects in the ribs and eventually freezes solid. Additionally, you need a siphon breaker at the highest point, preferably before the line exits the building.

With the siphon breaker installed you can omit the check valve to insure the hose completely drains to prevent freezing where it exits the building. With this configuration the water downstream of the siphon break will drain outside the building when the pump shuts off, so only a small amount of water is returned to the sump pit. If the pump still short cylces due to water returning to the pit from the discharge hose you need to either reduce hose volume between the pump and the siphon break or make your sump pit larger.

Ahhh The things us Yankees know about keeping sump pumps from freezing...
Perhaps the next suggestion from the south would be to add a little corn squeezings to the pit...

That would be a waste of good mash, yankee.

Redwood, I have a similar problem as I have a walk-in semi open basement in the back of my house in Mississippi and I am in the process of putting in a correct sump pump system as the one that is in there has just been kind of rigged to say the least. I have a vertical rise of about 8ft and will put in a check valve and protect that with heat tape and will angle the drain pipe ( 1 1/4 in. PVC) downward but want to make sure it drains properly so it doesn't freeze up, got to 14 degrees here lately. Could you please recommend a vacuum breaker. Thanks, Ben.

An air admittance valve would work fine...
But you'll need 1 1/2" to hook it up...

I could do 1 1/2 inch. It looks like that is an Oatey in-line vent, is that correct? And do you know of a good place to get one. Thanks, Ben.

Southern Man said:

Most New Englanders have a myopic view of the world, especially The South. Where I grew up in Massachusetts they taught us that the tallest mountain in the East was Washington in New Hampshire.

There's more than one way to plumb it apparently.

Click to expand...

Cadillac Mountain in ME is the first place on the East Coast that the sun reaches every AM....Just a little bit of usless trivia....

My folks have a real wet basement. They have two sump pumps one on each side of the basement (upstate NY). There are two outputs from the pump discharge. One is about 24" below ground level, and extends 20-30 feet out underground away from the house, then , about 3 ft above ground level there is another discharge that they use in the winter (controlled with a big ball valve above the pump) that discharges out on top of the ground outside. Don't know if its legit or whatnot, but it has worked for 15 years.

OK, I found them and the description said this. "Must be located at least 6" above trap arm top." Will I be able to screw this right into a tee where I will start my drop thus draining my line and keeping it from freezing or will I have to put a 6" riser on the tee then install this? Or is this 6 " rise for a different type of installtion?

Around here we route the 1-1/2" sump discharge out of the house a few inches and then turn 90 deg down into 4" PVC. The 4" is buried with proper pitch to drain the water away from the house out to daylight. Leaving an air gap between the 1-1/2" and the 4" prevents the airlock, allowing the pipe to drain.

Our temps stay below freezing for weeks at a time here. As long as the pipe is sized and pitched properly, it will not have a chance to freeze.

The problem I have is that this is an area that is under a raised house and is partially open and is also unheated. I sometimes don't get to go there for a few months at a time as well so I am trying to get all this straight and done as best I can to help from having problems. I appreciate the help and please feel free to do so, thanks Ben.

I see that a lot with trailer houses- good insulated skirting around the exterior keeps most from freezing. Metal pipe gets heat tape. If you can gravity drain at some point, it's possible to run a gutter heat cable through the inside of PVC. Don't use heat tape on plastic pipe- it melts!

This seems to work

This is 1.5" PVC joined to 3" PVC right as it comes out of the house. The basement is heated. There are 2 pumps and they both have been running this winter which is more than normal, but I'm working at home these days so maybe I just notice it more.

I keep waiting for these to freeze up. This is in Minnesota and it never got above freezing from Christmas Day through the last weeks of Feb. We had many days where it never got above zero. But the discharges do not seem to have frozen, incredible. This is also the north side of the house so the sun never helps out here.

The 3" PVC goes a couple feet into the ground then to a 90 deg elbow to about 10' of 3" PVC then joins to 3" slotted drain tile for the rest of the trip which is about 30 yards to the end. I wish I had used 4" PVC and drain tile to lessen the chance of freezing and clogging over time, but this has worked for over 6 years without incident.

I'm assuming the relatively warm water and air in the 1.5" pipe is just enough to keep it flowing down the cold 3" section and then the buried portion is deep enough to prevent freezing. I'm guessing our frost line is several feet deep, but some warmth may come from the basement to help and the lines pitch deeper and probably get below the frost line not far from the house.

The idea of making a small hole on the flapper of the back flow check valve is an excellent and economical idea. Most people disagree by making different assumptions. That is, the time that is needed to drain the water held in the riser pipe when it is busy pumping water, compared to the time needed to completely drain the pipe when it stops working. When the pump is busy pumping water such as in a heavy rain, it stops (when the sump is emptied) and resumes (the sump is refilled) pumping in fast cycles. So, when it temporarily stops while the sump is being refilled, only a small amount of water sink down into the sump through that small hole. This does not really reduce the pump efficiency. After the last cycle of pumping (rain stops), there will be long time to allow the water to completely sink down into the sump, emptying the pipe. If the pump works non-stop, then the issue becomes irrelevant. The only 2nd thing that is needed is to pitch the 'horizontal' segment of the discharge pipe after the riser to the exterior. So in the winter the entire pipe stays empty, eliminating the possibility of being frozen. The other ways of preventing discharge pipes freeze are more complicated, unnecessarily and cost more. - a non-professional opinion. Since my house had this issue, I thought about this way. But the local code is somewhat different (Minnesota). I wish this way be adopted as the code to make the job easy and less costly.