Clueless first time homeowner here. I purchased a home that has a sump with an attached radon mitigation system. The entire cover of the sump is sealed with caulk, so it's impossible to test if the pump is working by adding water. I do not know when the pump may have been tested last, the radon mitigation system was installed at the same time when the home was built in 2014. The entire sump is bone dry so I think the basement is very watertight, but I'd still like the peace of the mind of doing yearly testing to ensure the pump is working.

Is the white cap on the right side just a plug for an existing access port? Meaning I'd need to remove the caulk each time and recaulk?

If not, I've thought of drilling a 4" hole with a hole saw and capping it with a grommet/acrylic cap - something like this retrofit port.

Sump Full piping

2 Answers 2


Is there no union on the PVC pipe coming out of the lid?

How are you supposed to remove the lid and replace the pump?

To test the pump if there is no union I'd cut the pvc pipe and install a union. I imagine there is a check valve on the riser higher just out of frame? as long as you cut below the check valve you could, unplug the pump, fill the pit, put the pipe back together and test the pump.

  • I added a picture of the entire pipe. It looks like there is a union.
    – Dewitt83
    Nov 6, 2023 at 4:56
  • yeah you can just disconnect the furnco below the check and fill with water to test. Nov 6, 2023 at 5:01
  • This might be a silly question, but how much time do I have to reconnect the fernco after adding the water? Won't the pump start spilling it out of that pipe pretty quickly? Or do I need to unplug the pump first and just add enough water to ensure the float will trigger the pump once plugged back in and the ferno is added back?
    – Dewitt83
    Nov 6, 2023 at 5:58
  • if you are just testing that the pump will work then disconnect the pump, disconnect the furnco, fill, reconnect and plug in. Nov 6, 2023 at 6:49
  • actual pvc unions are a bit nicer as you don't need tools to disconnect and reconnect - if you decide to make any mods. Nov 6, 2023 at 6:50

The radon system is next to your sump, or in other words it is the 3 inch pipe that goes into the concrete. The 2 inch pipe coming out of sump is the sump discharge and the white cap does appear to be a test port to pour water into sump.

You can score the silicone around the sump cover so that you can gain access to the sump float and raise the float with your hand to test sump that way. Just be sure to reseal sump cover with clear silicone so that your radon system keeps working and so that the radon system does not pull conditioned air out of the home.

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