Is Your Sump Pump Weep Hole Spraying Water? Causes & Fix

Sump pumps are meant to keep your basement dry, but when the weep hole starts spraying water all over your basement, it’s function is quickly neutralised.

It’s annoying when this happens, but luckily it’s quite easy to resolve. In this article we’ll go over the causes of a spraying weep hole and we’ll instruct you in how you might fix the issue. Do keep in mind, though, that it is normal for some water to seep out of the weep hole and it shouldn’t cause any problems as long as it falls right back into the sump pit.

If it sprays water all over your basement floor, it is likely positioned too high.

The most common cause for a sump pump weep hole to spray water excessively, is that the hole is drilled at the wrong angle. Secondly, the weep hole may be sized too largely. Other causes for the weep hole to spray water may be due to it being drilled at a wrong distance to the check valve or the water line respectively.

When the weep hole never sprayed water before, and after a period of functioning properly suddenly starts behaving disorderly, other causes may be at play. We’ll cover all scenarios below and will also instruct you in how you can fix it.

Some sump pumps have a built in weep hole on the side. It is perfectly normal for those to spray water. When the discharge pipe sprays water excessively, however, you should fix the issue.

Other names for a weep hole are: bleed hole, vent hole and relief hole.

Function of the weep hole

Also known as a relief hole, the weep hole of your sump pump serves an important function. It prevents the sump pump from air-locking. When a sump pump’s discharge pipe is in air lock, the pump may pump all it wants, but the water can’t flow throughout the entirety of the pipe. What is interrupting the water flow, is that a gas has built up at a high point (right below the check valve) in the pipe, which interferes with the liquid continuum. 

To prevent the air from building up and to ensure that water can flow as is intended, it is crucial that air can escape. That’s why sump pumps should be installed with a weep hole. But it’s not supposed to spray water is large quantities.

Steps to find out what is causing the spraying

We’re going to test all the possible causes of water flowing out of the weep hole:

• Drilled in the wrong place
• Badly angled
• Too large diameter of the hole

Vertical position: where should the weep hole be located?

First of all, the weep hole should be above the water line. Otherwise water would get in where air should get out.

Secondly make sure that the weep hole is below the check valve. The ideal location is between the check valve and the sumps discharge. 

If you’ve made sure the vertical position is correct, it’s time to check the angle at which it was drilled.

How to check the angle of your weep hole

One of the most common mistakes during weep hole drilling, is that it is drilled at a horizontal angle, or even at an upwards angle into the pipe. This would naturally allow water to start spraying very easily.

The ideal angle of a weep hole is 45 degrees downwards. 

To check if your weep hole is in fact drilled at 45 degrees, simply stick a thin stick or ideally a straw inside the weep hole, aligning it with the surface of the hole. It will stick out enough so that you can measure / gauge the angle it makes with the pipe itself. Simply measure the angle with a drafting triangle or estimate it on sight. 

If it’s not at a 45 degree angle, chances are that it’s drilled too horizontally. Alternatively, weep holes that are drilled too vertically can also allow spraying, because the hole is too much in sync with the direction the water is flowing in.

How big should a weep hole be?

There’s two ways to answer this question. One involves a lot of maths so I’ll provide a math-free answer first. Feel free to skip to the next section after you’ve read the short answer in bold – just know that there’s no one ideal weep hole size for any situation.

Typically, weep holes for sump pumps are sized between ⅛’’ (3.2 mm) and 3/16’’ (4.78 mm).

But as I said, you’ll need a surprising amount of math to calculate it precisely. So much so, that I’ll lose 99.99% of my readers if I were to explain it here. I’ll argue that you don’t really need to know it precisely for the purpose of sizing a weeping hole for your sump pump discharge pipe. As long as your hole is sized anywhere between the two values I’ve given above, it’ll be safe to assume that the size of the hole is not the problem. The larger of the two values (3/16’’) is more appropriate for stronger sump pumps (1HP and above) while the smaller hole is appropriate for sump pumps that pack a smaller punch.