Guest
Yes, Stephan; there should be a valve near the water meter to shut off water to the house. If a glass of water prevents air from enteriing an open tap upstairs, the water will be drawn in by suction as water leaves below the slab.
Copper tubes have been in slab houses since the 1940’s. Some of them are still working. The tubing in mine has been working for 26 years. Local damage can occur from shifting, corrosive ash in the cement mix, soldered connections inside the slab, or freezes. It may be time for new above-slab tubing to replace that in the slab.
