Here's a riddle I would appreciate feedback on.

We have a 31 year old slab foundation we have to reuse do to DemoRat tax laws and we are getting ready to erect SIP walls and replumb with PEX. Meanwhile our gas bill has doubled, the floor is very warm in several spots and we hear an running sound inside several drains.

Typically any lay person would think "slab' leave, but here's the kicker:

Increased gas bill (double)
Hot floors (in 3 locations)
No ("NO") increase in our water bill

How can that be unless there is somehow a steam (vs water) leak or we're on top of a natural geothermal old faithful?

While waiting for the good old boys to approve our SIP plans at the city we are taking caution to turn off the water main frequently... Any thoughts?

John