Water Damage in Palo Alto: Eichlers, Radiant Slabs, and a City Utility

Closing the main does not always stop the water.

Radiant floor heating is a closed loop. It has its own supply, its own manifold, and in mid-century Palo Alto homes it is embedded in the slab in tubing that is now decades old. When that tubing fails, closing the house main does nothing, because the loop holds its own water and the boiler or heater keeps feeding it. What you need is the isolation valve at the manifold, usually in a utility closet or the garage, plus power off to the heating system.

The symptoms are also different from a plumbing leak. A radiant leak shows up as a warm strip of floor that does not correspond to a room being used, a heating system that runs constantly without reaching temperature, or a pressure gauge on the boiler that keeps dropping and needing topping up. If somebody has been adding water to the loop regularly, the leak has been running for a long time.

The other Palo Alto specific is the utility. Water, electricity, and gas here all come from the City of Palo Alto Utilities rather than from PG&E, so there is one municipal number for a street shutoff and one for the power, and that is genuinely simpler than the rest of the Peninsula. It also means the rebuild coordinates through the city on both trades, which our own C-10 crew handles rather than waiting on an outside electrician.