Flushing and Strapping a Water Heater

How often should you flush a water heater?

Follow your heater's manual; the two A. O. Smith manuals read for this page differ. The February 2023 manual for its standard gas ultra-low-NOx models says drain and flush after the first six months of operation to see how much sediment forms, then at least annually, and more often "if there is a lot of sediment". The older manual 326940 recommends draining and flushing "every 6 months".

Rheem's lifespan article says flush annually and replace the anode rod every 3 to 4 years. The six-month first flush is the useful reading: what comes out tells you whether yearly is enough for your water.

Upkeep and strapping readings

• 6 monthsFirst drain and flush, then at least yearlyA. O. Smith manual 100283020 (2023)
• 2 strapsUpper third and lower third of the tank2025 California Plumbing Code 507.2
• 4 in.Minimum gap between the lower strap and the controls2025 California Plumbing Code 507.2
• 120 galLargest heater covered by the state strapping lawHealth and Safety Code 19211

How do you flush a tank water heater?

Cool the water, shut off the heat and the cold supply, then drain through a hose. The steps below follow A. O. Smith's 2023 manual for a gas model; electric and heat pump models switch off at the breaker instead, so use your own manual.

1. Turn the gas control to OFF and close the manual gas valve to the heater.
2. Open a hot water faucet and let it run until the water is cool. The manual says this may take 10 minutes or longer and warns about scalding.
3. Connect a garden hose to the drain valve and run it to a drain, outdoors or into buckets.
4. Turn the cold water supply valve OFF, open the drain valve, and open a hot faucet to help the tank empty.
5. If a lot of sediment came out, open the cold supply with the drain open and let water run until no more sediment drains.
6. Close the drain valve, refill the tank with a hot faucet open to let air out, then relight following the label.

The manual adds that sediment can clog the drain valve; if the tank will not drain, it says to contact a qualified person. It also pairs the flush with an anode check, since the rod corrodes to protect the tank and is a consumable part. Do not turn the heat back on until the tank is full.

Does flushing matter on soft Sacramento water?

It matters less on river water than on groundwater, but the six-month check still tells you. A. O. Smith says the amount of sediment depends on tap hardness, temperature settings and other variables. Reports print hardness in ppm, which equals mg/L.

City of Sacramento water averaged 83 mg/L (4.9 gpg) across the system in 2025, according to its 2025 water quality report (published June 2026), and its wells ranged from 15 to 154 mg/L; USGS calls 61 to 120 mg/L moderately hard. Folsom's 2025 report gives 26.5 mg/L, and Roseville's Folsom Lake water is 26 mg/L, rising when its wells are in use. On a groundwater system such as Rio Linda/Elverta, 100% wells at an average of 99 mg/L (5.8 gpg), or Sacramento Suburban's wells at 120 to 130 mg/L, expect more in the bucket.

If you use a softener, the sediment may drop but the anode works harder. A. O. Smith's 2023 manual says the rod depletes faster with a softener and should be inspected more often. Whether a softener makes sense at all is on the do you need a water softener page, and hardness for every supplier is on the hardness by district page.

What strapping does California require for water heaters?

Two straps: the code wants one within the top third of the tank's height and the other within its bottom third. Health and Safety Code 19211 says all new and replacement water heaters, and all existing residential ones, "shall be braced, anchored, or strapped to resist falling or horizontal displacement due to earthquake motion", at minimum as the California Plumbing Code sets out.

The 2025 California Plumbing Code, section 507.2, places the straps "within the upper one-third (1/3) and lower one-third (1/3)" of the heater's height, and at the lower point keeps them at least 4 inches above the controls. The law covers standard heaters of 120 gallons or less for which a pre-engineered strapping kit is readily available.

Two related points from the statute: a seller of a home with a water heater must certify in writing that it complies, and a building in violation is deemed a nuisance. The same code section family also requires a base at least 3 inches above the ground for a heater standing on earth (507.4) and a drain pan where a leak would cause damage, such as in an attic (507.5).

How do you check water heater strapping?

Measure the tank and look at where the straps sit. Divide the height into thirds: one strap must fall in the top third and one in the bottom third, and the lower one must clear the gas control or element cover by 4 inches or more.

• Count two straps. One strap around the middle does not meet 507.2.
• Check the anchors. Each strap should be fastened to the wall as the kit's instructions show, with no loose bolts.
• Look for a gap. A heater that can rock or slide away from the wall is not restrained.
• Check after any work. A replacement heater needs strapping under the same law, and a permitted install is inspected.

If the strapping looks wrong, a licensed plumber can correct it with a kit made for the tank's size. A. O. Smith's manual points California owners to the state's bracing instructions; the statute and code above are the binding text.

What else should a yearly check cover?

The relief valve, the anode, the pan and pressure. A. O. Smith's 2023 manual says to operate the temperature and pressure relief valve annually and inspect it every 2 to 4 years, following the label on the valve. Its older manual says to lift the lever several times and confirm the valve seats and operates freely, keeping clear of the discharge line.

Read house pressure with a gauge on a hose bib. The California Plumbing Code requires a regulator where static pressure exceeds 80 psi, and A. O. Smith suggests setting one to 50 to 60 psi; its manual also calls for a thermal expansion tank on a closed system. The water pressure and regulators page covers the test. If the heater is near the end of its life, the page on how long water heaters last sets out repair-or-replace signs.

Downstream questions

Further down the channel

• Folder: Water heaters in the Sacramento region
• Water heaters: Signs a heater is near the end
• Water heaters: Rebate for switching to a heat pump
• Start at the home page