Sump Pump Installation: How to Drill a Weep Hole

Installing a sump pump can be tricky, but it’s a crucial part of keeping your home dry. One of the most important steps in installing a sump pump is drilling a weep hole. But what is a weep hole, and why do you need one? A weep hole is a small hole that allows water to drain out of the sump pit. This prevents the pit from filling up with water and causing the pump to work overtime. Weep holes are especially important if you live in an area with high water tables or if your sump pit is prone to flooding. This article will teach you what the weep hole is and what it is used for along with how to install it properly!


What is a Sump Pump Weep Hole?

A sump pump weep hole is a small hole that is drilled into the sump pump. This hole serves two purposes. The first purpose is to allow water to drain from the sump pit when the pump is not in use. This prevents the sump pit from becoming full of water and overflowing. The second purpose of the weep hole is to allow air to enter the sump pit. This is necessary because the sump pump needs air to function properly. Air in your pit, or basin, is necessary because the system uses a float switch to turn on and off. The float switch is a device that is used to sense the water level in the sump pit. When the water level rises, it activates the sump pump. If there is no air in the sump pit, the float switch will not be able to sense the water level and either never turn on or always stay on. Most sump pumps will benefit from a hole drilled into the PVC discharge pipe below the check valve to prevent an air lock from happening, which can reduce the life of your pump.

When Should a Pump Weep Hole be Drilled?

A weep hole should be drilled when the sump pump is installed. This ensures that the pump will work properly and that your home will be protected from flooding. Just about every sump pump would benefit from having a weep hole (otherwise known as relief hole) but it’s not always necessary. Having a sump pump weep hole will extend the life of your pump and is recommended to have by the most well known manufacturers including Zoeller.

It is especially important to drill a sump pump weep hole if you have an airtight cover or seal on your pit, like the ones that can be siliconed down to the concrete so to prevent radon from entering your home. Sump pumps that are covered this way can create an air lock inside the pit that could reduce your pumps life and may even make it not function at all if the float switch has trouble detecting the water level. You can prevent air locks by putting a weep hole in your discharge pipe because after the sump pump finishes its cycle it will let the water fall back into your basin and then air will shortly follow through your newly made sump pump weep hole.

How to Drill a Weep Hole

Drilling a pump weep hole is a simple process. First, you will need to find the spot where you want to drill the hole, usually in the PVC plumbing pipe that makes up your discharge pipe. It’s best to pick a spot on the pump discharge that is below the top of the basin so any water that flows out goes right back into the pit. You may even chose to drill the hole below your check valve but above the sump pump discharge, so that any water that is still trapped in the pipe can flow out and into the pit, which also allows air to enter through the discharge pipe.

Some people like to put a 45 degree angle in the hole they drill (drilled upwards from the outside of the pipe) so that the water that comes out will be directed downwards and straight into the bottom of the basin, instead of upwards towards your check valve.

It is important to make sure that the new weep hole is not too close to any electrical wires or pipes. Once you have found the perfect spot, you will need to drill a hole that is large enough for water to pass through. A good rule of thumb is to drill a hole that is about ΒΌ inch in diameter. After the weep hole has been drilled, you can place the sump pump in the pit and begin using it!

Frequently Asked Questions

Can I drill more than one weep hole?

Yes, you can drill multiple weep holes if you would like. However, it is not necessary. One weep hole is typically sufficient for one pump.

Do I need to drill a weep hole if I have an airtight sump pit?

It’s not always necessary to have weep holes on your discharge line, but if you do have an air tight sump pump you will want to have one to prevent an air lock. It is generally a good idea to drill one anyways so your float switch can function properly.

What should I do if my sump pump doesn’t have a weep hole?

If your sump pump does not have a weep hole, you can drill one yourself. However, it is important to make sure that you do not drill the hole too close to any electrical wires or pipes.

Should I drill the weep hole above or below the water line?

It is best to drill the hole below the water line. This ensures that any water that flows out goes right back into the sump pit.


Weep holes are an essential part of sump pump installation. By following the steps in this article, you can be sure that your sump pump will work properly and that your home will be protected from flooding. If you have any questions or concerns, please feel free to contact a professional sump pump installer. They will be able to help you with anything you need and ensure that your sump pump is installed correctly. Thanks for reading and good luck!


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Bill is a DIY plumber, handyman, and homeowner with more than a decade of experience. He has replaced and repaired sump pumps, backup pumps, float switches, check valves, and many other things around his family home. An engineer and tinkerer at heart, he is always looking to see how things work and taking on new home projects that help him grow his skillsets. He is a husband and father of two boys, has a bachelors degree in Computer Engineer and minor in Mathematics and likes to make homebrew beer in his free time.

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