How to Pipe Sump Pump Discharge

Tom Raley

If groundwater or storm water tends to collect in the space under your house or other unwanted areas, you may need to install a sump pump. These pumps are activated when the water reaches a certain depth in a sump pit.

From this point, the water must be removed from the pit in such a manner as to prevent it from easily flowing back into the area from which it was removed. You must keep several considerations in mind as you plan how to pipe the discharge line from your sump pump.


Use a one-inch PVC line for your drain, it will be easier to work with and less expensive than a larger pipe.


If your home is on a septic system, do not have the water drain toward your field lines. The excess water can cause a strain on the system.

Plumbing Your Sump Pump Discharge Line

  1. Check all local codes and regulations before beginning this project. In many areas it is illegal for you to tie the drain into your municipal sewer system. Municipalities like to control, as well as charge for, both the water that comes into your home from their water system and the water that leaves your home via drains to their sewer system. If your city does allow connection to your sewer drain line, this is by far the easiest and most efficient method of plumbing the sump pump discharge line.

  2. Secure a short section of PVC pipe to the discharge port of the sump pump. This piece of pipe should extend up and out of the sump pit. On the upper end of this install a check valve. Use PVC cement to secure the valve in place with a watertight seal. This valve will allow water to pass out of the sump pit but will prevent it from flowing back when the pump is turned off.

  3. Cut another section of PVC pipe long enough to reach from the top of the check valve to the center of an overhead floor joist. Use PVC cement to get a good seal, but be certain not to apply too much cement and cause the cement to overflow and flow back into the valve, rendering it useless. Atop this pipe, install a 90-degree elbow facing the exterior wall you plan to route the drain through.

  4. Take careful measurements of the location and height of the elbow. Transfer these measurements to the exterior wall where you plan to install the drain line. Double check all measurements before drilling a pilot hole using a 1/4-inch drill bit. With the pilot hole in place, use a larger bit to drill a hole large enough to fit the drain pipe. You want the hole to be just large enough for the pipe to fit through with as little excess room as possible.

  5. Cut a piece of PVC pipe long enough to travel from the elbow, through the exterior wall, and out of the house. Clean all ends of the pipe and secure them in place with PVC cement. Use standard caulk to seal around the drain pipe where it exits the house. Even the smallest opening can allow insects and other pests to enter your home.

  6. Secure a final fitting on the end of the drain line. This can be either a 30-degree elbow or a 90-degree elbow. This fitting should be directed toward the ground. Just below this fitting you can place a cement divert like used at the base of gutter down spouts, This will help disperse the water and prevent erosion. In some instances, the drain line may be continued on to an outer flower bed to act as an irrigation system. The longer the drain line the harder your pump has to work, so don't extend the drain too far and cause unneeded stress on your system.