Expanding foam

[yankee500]

i have a water supply in my garage (house only rented) the alcathene pipe comes up through what looks like a 4" pipe. but there is quite a hole ,
when it rains it comes up into the garage . so i thought i would fill it with foam. i have never used foam before so dont' know which to get.
can anyone help please.

 

[Tombstone]

there should be a metal cap around the pipe on the roof, when filling a big gap make sure you have something underneath as the foam will drop out before its fully cured.