How to Design and Install
Radon Sump Systems

Radon sump systems are very desirable because of the potential for great air movement across the foot print of the basement. This is due to drain-tile or french drains placed in a bed of gravel often along the entire footing of the foundation. These drainage pipes are perforated and laid in a bed of gravel so rising water levels can enter the tubes and flow to the sump for discharge from the building. So the french drain pipes double as a great way for the radon fan to gather radon gas to the vent pipe and send it out above the building.

Sump System Configurations

Please view the diagram and table below to decide if a radon mitigation will work with your sump system.

radon sump diagram
Sump System Configurations and Radon Mitigation
Sump Set Up Probable Situation Will it work?
2 pipies (A+B) entering basin
parallel to foundation
Likely an interior drain-tile loop. Excellent results can be expected.
1 pipe (C) entering basin perpendicular to foundation Usually means an exterior loop. Can be tied into an interior loop also. Exterior systems can produce excellent results. Walkout basements may have only partial loops and daylight drains which can reduce effectiveness.
1 pipe entering a sump centrally  located in the basement Likely an interior drain-tile loop Excellent results can be expected.
3 pipes (A,B,+C) A combination interior and exterior loop. Excellent results can be expected.
No pipes with weep holes and or an open bottom to the soil. No drainage pipes or gravel can be expected. Not a good location for a radon vent pipe.

Interior French Drain/Drain Tile Example

Taking a look down the pipe with a flashlight or using a tape measure will verify the actually configuration of the system. Some times things aren't always what they seem to be, it's worth a look.

Radon Sump Pipe Location

The vent pipe can either be located directly on top of the sump cover or into a hole made in the floor. If you have a sump pump in your pit that needs attention, placing a hole over the drain tile will allow for easier access to the sump when required. Or if your vent pipe's exit point from the basement is not near the sump, why not locate it there instead. Shorter pipe runs are always better. Just be sure that you can tap into the drain-tile or if you have gravel under the floor you can place the pipe just about anywhere.

The radon vent is placed right over the drain tile in this photo. This is worthwhile if you ever anticipate going back into your sump to change the pump out. NOTE: Cut a hole in the top of the tile to allow for good air flow.

radon suction point

If the pipe is installed in a sump with a pump, plan ahead for an emergency. I use a coupling so the pipe can be moved out of the way when the sump pump needs maintenance.

radon mitigation sump

Note with high air flows from drain-tile and gravel beds, 4" pipe is always the best bet.

Radon Mitigation Sump Cover

For any radon mitigation sealing is very important. You don't want to draw the conditioned air out of your home and blow it out the roof.
So the sump requires a cover that can be sealed and clear is preferable to view water levels.

Here are some other considerations for sealing a sump for radon mitigation:

  • If you have a pump it needs to be a submersible type for proper sealing.
  • Do you have water that flows into the basin when it rains or if you have other appliances draining into the sump? You will want a special sump cover drain. These allow water down but stops air draw from the house.
  • If you have any untrapped drains using the sump these will have to be retrofitted.
  • A good design will allow for easy access to the sump basin by using an inspection plug. Otherwise the whole cover will have to be removed.

For more detailed info about radon mitigation sump covers and to view radon sump supplies please view them here....


Radon Fan Selection for Sumps

  • Smaller well sealed basements <1000 sq/ft can often be mitigated with the RP140 or XP201.
  • For basements up to 1500 sq/ft the RP145 and the XP151 will usually produce good results.
  • For larger basements the RP260 and RP265 fans are a good choice. I use the XR261 for outside installs because of their slim design. These fans are only beneficial with 4" pipe as these are 6" fans. 6" pipe is rarely required in residential radon mitigations.

Return from Radon Sump Page to Radon Mitigation Page

Return from Radon Sump Page to Indoor Air Pollution Page

New! Comments

Have your say about what you just read! Leave me a comment in the box below.
Site Search


Shopping Cart Total








Radon Mitigation
Design Pages


radon store
Please see our Healthy Air Solutions Store for all your radon mitigation supplies...

radon fan couplings
Mitigation Design Help

radon fan cap
Radon Pipe Guide

radon pump
Radon Fan Guide

Airchek radon kit
Radon and Sumps

radon crawlspace
Radon and Crawlspaces

Need some more advice?
Please fill out the form at the bottom of this page...