On the off chance you meant where water could get into the TPS, see the (2) included pics.
When my 5th or 6th one failed, I carefully opened it with a hammer to look inside and I could easily see water had found its way in.
The only place I can see it getting in would be the parting-line in the plastic (particularly the bottom of it). This pic is of one of four spares and hasn't been sealed yet, but the parting line is where I smear a bit of clear silicone on them.
The sealed one on the truck has been quietly doing its job now for 11 years without an issue.
The 2nd or 3rd one that failed would only pass 70% throttle opening to the ECU (NO CODES) when the Throttle Body was wide-open; and it just about drove me nuts trying to figure out why my truck was down 100 (?) horsepower...
After I installed a new one, it still didn't help until I did the battery-cable trick as the ECU was still working with the older, bad info from the failed TPS. Fried the poor Pirellis all the way through 2nd gear (insert smile here) after that.