Water heater earthquake straps: what the code says and how to install them

Why water heaters get strapped

A 50-gallon tank holds more than 400 pounds of water alone (water weighs about 8.3 pounds a gallon), sitting high on a narrow base. Washington's Department of Health says experts changed how water heaters are strapped after the 1989 Loma Prieta and 1994 Northridge earthquakes, because so many tanks burst through the single strap of plumber's tape that was common before.

There's a second reason: a standing water heater is an emergency water supply. The department notes that after a disaster you can draw fresh water from the drain valve with a garden hose and an open faucet, provided the tank stays upright, and that the electricity or gas should be off before you open the drain.

What the code requires

A. O. Smith's manuals say that if your area is prone to earthquakes, use special straps as required by local building codes, and that other locations may have requirements similar to California's, so check with local and state authorities. Whether your house falls in one depends on its location and the code edition your jurisdiction adopted; your building department can tell you.

How many straps, and where

• Two. The code wording, upper one-third and lower one-third, means one strap near the top of the tank and one near the bottom. Washington's Department of Health likewise says to secure both the top and the bottom, rather than just the top or the middle.
• Clear of the controls. Position the lower strap so it doesn't cover the gas control or the electric access panels, so the heater can still be serviced.
• Tight to the wall. The department says there should be very little space between the tank and the wall so it can't tip backwards; if the gap is more than 1 or 2 inches, attach a wooden block to the wall with long lag screws.

How to install water heater straps

These steps follow Washington's Department of Health guidance. A commercial strapping kit, sold in hardware stores near the water heaters, includes the strapping, lag screws, washers, spacers and tension bolts.

1. Find the studs behind the heater, or add a wood block if the tank sits more than an inch or two from the wall.
2. Use heavy-gauge metal strapping, not plumber's tape.
3. Wrap each strap 1½ times around the tank. Start at the back, bring it to the front, then take it back to the wall.
4. Fasten to the studs or block with several 1/4-inch by 3-inch or longer lag screws and oversized washers. Into concrete, use 1/4-inch expansion bolts instead.
5. Repeat for the second strap in the lower third, then tension both so the tank can't move.

If your kit's instructions differ, follow them, since the code also allows strapping per the appliance manufacturer's recommendations.

Don't forget the connections

Washington's Department of Health also recommends replacing rigid copper and metal piping at the heater with flexible gas and water connectors, so the lines can move a little without breaking. A. O. Smith's gas manual calls for a new CSA-approved gas supply line. Gas connections are a job for a qualified installer (see water heater shut-off valve for where to shut things off in an emergency).

Strapping when you replace a heater

A replacement is the easiest time to add or upgrade straps, and in places that require them the new install has to meet the code. Ask your installer whether straps are included. Replacing a water heater may also need a permit and inspection where you live (see do you need a permit to replace a water heater). A heater in a garage may need other protections too, such as a drain pan in some locations (see water heater drain pan) and an expansion tank if your system needs one (see water heater expansion tank).

Utah homes

Because Utah's amendment applies to all water heaters, homes in Salt Lake City and the other Utah towns we serve should have two straps on every tank. If yours has none, one strap, or plumber's tape, it's worth fixing.

Local pages mentioned

• Salt Lake City, UT