re: Located a termite nest, how best to destroy

My first attempt would be to dig around the slab like you would to saturate the area with some type pesticide for termites and saturate the ground with boiling hot water.

I know they are different species, but I got rid of a large red ant infestation in my compost pile doing just that a few years ago.

I would think the pipe supplying your water is well below the surface and would not be affected if you used some type termite baits or even saturated the ground with termite pesticide.