Shutoffs and straps: gas, water and power in a San Francisco home

Most people meet their water main for the first time holding a towel, while water runs through the ceiling of the flat below. A quiet Saturday morning is a better introduction. Walk the house once, find the three places where water, gas and electricity can be stopped, test the one shutoff you're allowed to test, and leave a label and the right tool at each. It takes well under an hour.

#Where the three shutoffs are in a San Francisco house

In a row house with the garage at sidewalk level, all three usually sit within a few steps of each other, often behind years of storage. Flats and apartment buildings scatter them: gas meters in a row in a shared garage, the panel in a hall closet, the water valve behind the owner's locked door.

#Water: find the main, test it, label it

This is the one shutoff worth testing, because a valve that hasn't moved in thirty years may not move when you need it. Start with the SFPUC's own description of the valve: usually a round-handled gate valve built to shut off and turn on slowly, or a ball valve with a blue lever, and typically the largest valve coming out of the wall.

1. Follow the line in from the sidewalk

   Start at the meter box and walk the path the pipe would take into the house: the front wall, the garage, a crawlspace door. A tag from an earlier owner, or a valve someone painted red, is a good sign.

2. Tell a gate valve from a ball valve

   A wheel means a gate valve: turn it clockwise until it stops, which can take several turns. A lever means a ball valve: a quarter turn, until the handle sits crosswise to the pipe.

3. Test it on a dry day

   Close it, open a faucet on the top floor to confirm the water stops, then reopen the valve slowly. If the wheel won't budge, or water weeps from the stem, stop and leave it open. Forcing an old gate valve is how a test becomes a repair.

4. Label it, and tell someone

   Hang a tag on the valve and write its location inside the panel door. Show the person who feeds your cat; a valve only you can find helps only when you're home.

5. Keep the floor in front of it clear

   Boxes and bikes migrate toward valves. Leave room to kneel, and keep a flashlight within reach.

#Gas: find it, read it, leave it on

The gas valve is the shutoff you never test. PG&E's earthquake advice is to avoid turning off your gas without a clear sign that it is leaking, because once it's off, it stays off until PG&E turns it back on, which can take a long time when many customers are waiting. Your job now is to know where the valve is and what closed looks like.

1. Find the meter and its valve

   PG&E installs a shutoff valve at every gas meter. Meters are usually on the front or side of a building, or in a cabinet inside or outside it. In an apartment building they often stand in a row, one per unit; find the one marked with yours.

2. Read the valve without touching it

   The valve has a flat tab, the tang, that a wrench grips. Lined up with the pipe, it's open. PG&E says it is closed when the tang sits crosswise to the pipe, a quarter turn away.

3. Hang the wrench beside it

   PG&E suggests keeping a 12- to 15-inch adjustable pipe or crescent wrench near the valve. A hook by the meter beats a toolbox upstairs.

4. Label it for the household

   Mark which meter serves your home and show whoever else lives there. Renters: the city's ReadySF earthquake guide says to ask your landlord where the building's gas shutoff is.

5. Learn the three signs

   PG&E lists smell (the rotten-egg odor it adds so leaks get noticed), sound (hissing, whistling or roaring) and sight (dirt spraying, steady bubbling in water, dead plants over a buried line). After a quake, those signs, a visibly broken line or a leak you suspect are the reasons to close the valve. Shaking alone isn't.

#Automatic earthquake valves: who has to have one

The state's part is certification. The Division of the State Architect certifies two kinds of automatic gas shutoff valves for homes: an earthquake-sensitive valve that closes when shaking passes a design level, and an excess-flow valve that chokes off gas rushing out of a broken line. Installation falls to local building departments, and PG&E notes that some cities and counties require these devices, generally for new construction and significant alterations or additions.

Milpitas is a Bay Area example. Its building office requires an excess-flow device at the appliance whenever a gas appliance is installed or replaced, and an earthquake or excess-flow valve after the meter when the gas line is altered or extended, under a permit, by a licensed contractor. Research for this guide found no such San Francisco requirement; ask the Department of Building Inspection before assuming either way.

Either automatic valve goes on the house piping past PG&E's valve, regulator and meter, and the CSLB's C-36 plumbing class names gas earthquake valves among the safety devices a plumbing contractor maintains and replaces. If one trips, treat it like a closed meter valve: no reset until a qualified professional has checked the lines.

#Power: the main breaker and a panel you can read

1. Find the panel

   In houses here it is often in the garage, on a back porch or in a hall closet, and it may be nowhere near the meter outside. Open the panel's door. The cover behind that door, the one held on with screws, stays on.

2. Find the main

   In many panels the main breaker sits apart at the top, bigger than the rest and stamped with its amp rating. Some older panels have no single main, and some houses still have a fuse box; if yours is either, ask an electrician to show you what shuts everything off.

3. Make the labels true

   Pencil labels from a long-gone owner are often wrong. Map the circuits with two people and a phone: one switches breakers off one at a time, the other reports what went dark. Then write a new directory.

4. Know PG&E's two rules

   After an earthquake, shut off the power at the main if you suspect damage to the wiring, and stay well away from any downed line outside. Day to day, a breaker that trips again with everything on its circuit unplugged is a call to an electrician.

#The water heater strap California requires

A full tank is heavy, top-heavy and tied to a gas line and two water lines, which is the whole case for strapping it. Health and Safety Code Section 19211 requires all new and replacement water heaters, and every existing residential one, to be braced, anchored or strapped against falling or sliding in an earthquake. It covers standard heaters up to 120 gallons for which a pre-engineered strapping kit is readily available, and it sets the California Plumbing Code as the minimum.

The current edition, the 2025 California Plumbing Code, carries the rule in Section 507.2, and Bay Area building departments such as Dublin's summarize it this way: straps within the upper third and the lower third of the tank, with the lower strap at least 4 inches above the controls. The State Architect's bracing guidelines fill in the rest: two sets of straps for a tank of 52 gallons or less, a third set at mid-height up to 75 gallons, and local approval for anything bigger.

Selling? Section 19211 makes the seller certify in writing that the heater complies, which the standard transaction documents can carry; the selling guide covers the rest. Renting? The same section bars an owner from evicting anyone in order to comply and treats a building in violation as a nuisance. That is general information, not legal advice. If the tank is near the end of its life, read about the Bay Area gas water heater rule first.

#After the shaking stops: an order of checks

1. First minute

   People, then your nose

   Check that everyone is unhurt. Then use your nose and ears before your hands: if you think gas is leaking, PG&E says to use nothing electric, not even a light switch.

2. If you smell gas or hear hissing

   Out, then call

   Everyone outside and upwind. Call 911 away from the building, then PG&E. Close the meter valve only if you can reach it safely.

3. Next few minutes

   Water

   Check under sinks, around the water heater and along exposed pipe. Spraying or pooling water that a fixture stop won't control means closing the main; the first 48 hours guide takes it from there. A leak on the SFPUC's side of the meter goes to 311.

4. Then

   Power

   Sparks, a burning smell or wiring pulled loose: switch off the main breaker if you can reach it without standing in water. Treat any downed line outside as live.

5. If the power is out

   Unplug the big appliances

   PG&E suggests switching off and unplugging major appliances so they aren't hit when power returns. With no sign of a leak, leave the gas on.

6. Over the following days

   Aftershocks

   ReadySF warns they can feel as strong as the main shock. Recheck the straps and connectors, hang the wrench back up, and finish the furniture in the room-by-room earthquake guide.

#Apartments, flats and the building's shutoffs

A San Francisco building with three or more units is an apartment house under the Housing Code's definitions, and there the owner carries much of this. Section 712 requires existing apartment houses to post directions to the utility shutoffs, with operating instructions, in a public area. Tools needed for a shutoff must be kept near the valve, reachable by tenants but secured against tampering.

So look for that notice by the mailboxes or in the garage, find your unit's gas meter in the row, and ask which valve shuts off your water. If nothing is posted, or the wrench has wandered off, point the owner to Section 712. The strap rule covers the building's heaters too, and the owner's alarm duties are in the smoke and CO alarm guide.