This doesn't look like a great candidate for this type of repair.I would seal the sides with some more concrete or an exterior type of caulk.  

Well, if the concrete block wall is not sealed, then the water would come in that way.

Then I sealed it with 2 coats of high performance sealer from Sherwin Williams (very strong and durable).

@Wilson Churchill,You could try using the fitting that's a slightly too small, use your tube cutter to crimp it down, then soft-solder it to seal the joint.

The sprayfoam is mold proof and vapor impermeable, thus sealing it off. 

Are the p-traps sealing up properly?

After 2 weeks of dealing with several different forms of water damage (leaking water heaters, refrigerator lines cracking, toilet tank seal cracking, etc), I'm going on the offensive.  

Milind,Yes, your solution will work and is the right way to do the repair, just make sure you seal all the threads real good and test the joints with spray to make sure no gas is leaking out of them. you may want to test as many of the old joints that you can as well, just to make sure no gas is leaking out of them.

Cats mark, so usually something that bad means taking out the bottom 4 feet of drywall (as in a flood) and putting new drywall up there - and maybe sealing the studs underneath before doing it, and/or changing out the insulation depending on how much saturation the drywall received.

Valid point, I think just by doing some minor things like keeping the bedrooms carpet and sealing the electrical boxes is a enough.