Loud thumping sounds coming from radon pipe
Without seeing the details of your piping, can't say for sure where the water might be coming from.  But, the &quot;intake&quot; pipe for the radon exhaust, usually coming off of a sump pump well or pit, should not be going into any water.
Our previous house had a similar radon mitigation system, but we never had to use it.  The lower part of the pipe connected to a tight fitting lid on the sump well.  It did NOT go down into the well itself, and so was never near the water that was in the sump well.