Informational Guide

Sump Pump Weep Hole (What Is It & Do You Need One)

by Ian Haynes

Several houses have recurring issues with flooded basements due to lousy weather or leaking pipes, damaging items, and the house's foundation.  

If you too have this issue, you need to install a sump pump in your basement with a sump pump weep hole. Read on as we get you started: 

Sump pump discharge pipes can often get air locked. Due to this, the line does not pump out the water and can end up flooding your basement.  

To prevent this, weep holes are installed. In the simplest way possible, a weep hole is drilled into the discharge pipe to allow the trapped air to escape.  

Remember, not every sump pump needs a weep hole, but this is more of a preventive measure than a fix. However, it is advised to have a weep hole in your discharge pipe. 

sump pump hole

Why Do You Need A Sump Pump Weep Hole? 

A sump pump can get air locked due to a large amount of water discharge in the sump pit. When the motor starts, the water tends to get stuck on the pump, trapping air inside it.  

This prevents the pump from pushing the water out of the discharge pipe due to the extra air. This means your pump will sound like it is working, but no water will get pumped out due to the air pocket. 

Trapped air can cause your pump to overflow and flood your basement. To let some of this air escape, a weep hole is drilled into the discharge pipe to keep the water flowing out of the discharge pipe.  

Therefore, installing a weep hole can save you from serious issues resulting from airlocks. 

Sump Pump Weep Hole Installation  

Although not all sump pumps require a weep hole, it is advised to get one installed. Making a weep hole in a sump pump is not as easy just drilling a random-sized hole. Certain specifications go into the installation process.  

Here are the steps you can take to drill a weep hole for your sump pump discharge pipe yourself. 

  1. 1
    You will first need to remove your pump from the put after disconnecting the discharge pipe. This is because you will need to drill a hole, and doing it while in the pit is impossible. 
  2. 2
    Next, you will need to find a power drill with a 3/16″ drill bit. This is the specific size that the hole for the weep hole needs to be. 
  3. 3
    Next, measure the distance between the discharge line and the check valve. The hole needs to be drilled at a downward angle of 45 degrees angle between the check valve and discharge valve. 
  4. 4
    Ensure that the hole is no bigger than 3/16″. Anything bigger or smaller than this size will leave the weep hole ineffective. 
  5. 5
    Once you have drilled the hole, reinstall the sump pump in the pit and attach the discharge pipe. 
  6. 6
    Finally, when the sump pump is reinstalled, empty a bucket of water into the pit to test whether your system is working. 

And if you're wondering where to drill the weep hole in a sump pump, remember, it needs to be drilled below the waterline. This will allow the air bubbles to escape and prevent the pipe from creating air pockets. 

Here is a diagram to give you a better idea of where the weep hole needs to be installed. 

Weep Holes And Popular Sump Pump Brands 

There are several famous brands in the market for a sump pump. The top two that come to mind are Zoeller and Wayne. They offer high-quality sump pumps that can easily be installed. But, according to the brand, these brands also require a weep hole.  


Zoeller suggests making a weep hole between the pump and check valve of 3/16-inch. This prevents air bubbles and keeps the pump from air locking. 

Therefore, a Zoeller sump pump weep hole is tight, offering security and efficiency. 

Zoeller Sump Pump


Wayne sump pump weep hole is unique and displays a different design. Therefore, it requires a weep hole in the discharge pipe. This allows trapped air to escape. This is suggested to keep the discharge water from flooding your basement. 


Why does the weep hole on my sump pump spray water? 

A weep hole s installed to release the air in the sump pump, but there are often when the weep hole sprays water all over your basement floor. There are several reasons why this occurs. It could be because the hole was drilled too high, or maybe the angle of the hole is not at a 45-degree angle, or even if the gap is wider than 3/16-inch in diameter. All these play a part in the water spraying from the weep hole. 

How do you fix the weep hole that is leaking? 

Once you drill a weep hole and it starts leaking, there are two options that you can take. You can either replace the entire pipe with the weep hole and install a new pipe or fill the weep hole and drill a new one. It is easier to fill the gap with plastic repair epoxy and drill a new hole than replace the whole pipe. 

Does A sealed sump pump pit need to be vented? 

If your pit is sealed correctly, there is no need to be vented. That being said, if it is not packed perfectly, there is a possibility that dangerous gases can seep into your basement, not to mention the humidity due to the water at the bottom of the pit. 

What happens if the sump pump weep hole is blocked? 

If the weep hole is blocked, you risk trapping air in the sump pump, which will result in the pump not being able to pump the water out the discharge pipe. If there is a clog in the weep hole, try using a plumber snake to unclog the blockage. 


A weep hole is an essential addition to your sump pump. Air locking is standard in most sump pumps, and installing a weep hole can help release the air.  

However, air locking can cause several complications, such as your basement flooding due to the discharge water being unable to escape.  

Installing a weep hole is a preventive measure, and it is advised to install one in your sump pump. Make sure you follow the instructions down to the T. 

Ian Haynes is an expert writer who has successfully deployed over 500 plumbing pages and other related content. He has an excellent understanding of home plumbing issues and translates his experiences via Plumbing Lab so readers can have a better understanding of common household problems. Outside of his work, Ian likes exploring Brooklyn with his Labrador.