Sump Pump Weep Hole Guide

Last Updated on by Anthony Brown

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    Installing a sump pump but not sure what a Weep Hole (aka a relief hole) is – or where to install it? Our team of basement waterproofing experts put together a guide to help you drill your Weep Hole and avoid air lock!

    A sump pump weep hole may not sound important thanks to their silly sounding name but air locked pumps can mean a flooded basement and costly repairs. Pumps air lock and think they are pumping water when really they are only pushing air out the discharge pipe.

    Weep Hole Installation Guide

    Installing a Weep Hole on your pump system may sound confusing but it is actually easier than it sounds. If you paid a professional installer to dig and install your system they should have drilled the relief hole but you should always double check.

    Black - Decker 20v Drill

    Drilling a weep hole is easy with the right equipment. Most piping can be drilled with a normal power drill like the BLACK+DECKER 20V Drill. Make sure to take your time and drill on a flat surface.

    Step by Step Installation

    1. Remove your pump from the pit – Start by taking your pump out of the pit and disconnecting it from the drain lines
    2. Prepare drill – Find a 3/16″ drill bit and power drill
    3. Drill a Hole – Drill a 3/16″ downward at a 45 degree angle between the discharge line and check valve
    4. Reinstall pump – Reinstall your pump and reattach the discharge lines and power cord
    5. Test system – Test your pump system and weep hole by filling your basin with a few buckets of water

    Preventing Air Lock

    You may be shocked to see water going back into the pit while the pump is running but it is a necessary evil! This small loss in pump efficiency extends the life of your pump and stops air locks.

    Where to Drill a Weep Hole

    Your Weep Hole should be drilled between the discharge and check valve. The hole should be drilled downward at a 45 degree angle, pointing away from your pump but inside your pump pit.

    Make sure to disconnect your pump from the lines and place it in a place that is easy to drill.

    Above or Below the Water Line?

    A Weep Hole should be installed below the water line. This will allow hole to prevent air bubbles from entering the impeller chamber and causing an air lock.

    How Large is a Weep Hole?

    Weep holes should be a 3/16” hole – any larger or smaller and the hole will not be effective. The best way to drill a hole is with a power drill so you can quickly (and safely) drill a straight hole.

    Why do Sump Pumps Need Weep Holes?

    Sump pumps need Weep Holes (relief holes) in order to prevent air locking the impeller chamber. This is important because it allows air to bleed out of the interior of the pump that would normally keep the next cycles from starting.

    As an added benefit drilling a relief hole extends the life of most pumps and is even recommended by manufactures like Zoeller. Are weep holes 100% necessary? No, but why shorten the life of your pump!

    Frequently Asked Questions

    Do you need a weep hole in sump pump?
    Some models of sump pumps do not require a weep hole but many of the most popular models need a weep hole to prevent air lock.

    Where should the weep hole be on a sump pump?
    Different water pumps need weep holes in different locations. The most common spots is below the water line but check your  owners manual.

    Why does a sump pump need a weep hole?
    Sump pumps need weep drilled into the drain pipe in order to prevent air lock.