Plumbing in San Francisco is old pipe in a tight building, often on a hill. Galvanized supply lines narrow until a shower is a disappointment and then pit until they stain a plaster wall. Pressure is frequently low, and it gets worse at the top floor. Water heaters hide in closets that were not built for a modern tank, with no pan and no easy way out if the base lets go. Sewer laterals on hills can run a long distance to the main, and they fail under a sidewalk or a garden long before the kitchen sink looks guilty. A backup in a lower-level bath is a classic clue.
Drains and vents are fussy in these remodels of the past. A toilet that gurgles when the tub empties, a kitchen line that burps, or a smell from a dry trap on a rarely used fixture usually means a vent or a partial blockage, not a need for every new faucet in the house. Cast iron bells and old steel drains scale. Mixing new copper onto a corroded galvanized branch without a plan just moves the leak to the joint. Angle stops seize. When someone finally turns a buried shutoff, it may not reopen. Know where the water can be stopped before the wall is open.
Fog does not freeze pipes often, so the failures are age, corrosion, roots, and settlement on hillsides. A slab is not the usual story here. Raised floors and finished basements are. A leak can travel along a joist and stain a ceiling far from the pipe. Shared stacks mean you confirm which line is yours before you open a chase that serves another floor. Describe the symptom by fixture and by level. A top-floor pressure complaint and a basement backup are not the same trade conversation.
Call and say what the water is doing. Weak hot water, a stain, a backup, or a heater in a closet are enough detail to start. Mention a hill lot if the lateral is the suspect. The work has to fit old San Francisco piping, not a slab-leak script from a southern ranch.
Call the number on this page.