How do I make bathroom plumbing safer for kids?

Scald protection works in layers. The water heater sets the ceiling for the whole house. The valve at the tub or shower sets the ceiling at that fixture. Hand-testing the water is the last layer.

### Layer one: the water heater

The CPSC says "The majority of injuries and deaths involving tap water scalds are to the elderly and children under the age of five." It "urges all users to lower their water heaters to 120 degrees Fahrenheit." Its scald fact sheet gives the reason in burn times. It says most adults will suffer third-degree burns from 150 degree water in two seconds, and that "Even if the temperature is 120 degrees, a five minute exposure could result in third-degree burns."

To check your setting, the CPSC suggests holding a candy or meat thermometer under the faucet "first thing in the morning or at least two hours after water use." Adjust the heater using the maker's instructions, then check again. Our page on what temperature to set a water heater walks through the dial on gas and electric units, and why some homes store water hotter and mix it down.

### Layer two: the shower and tub valve

The plumbing code handles the fixture itself. The 2024 International Plumbing Code (IPC), in Section 412.3, says shower and tub-shower valves "shall be balanced-pressure, thermostatic or combination balanced-pressure/thermostatic valves" that meet ASSE 1016 or a matching standard. It also says those valves must have "a means to limit the maximum setting of the valve to 120°F (49°C)."

Here is what those words mean at home.

• A pressure-balance valve reacts when cold water pressure drops, such as when someone flushes a toilet, and cuts the hot side so the mix does not spike. Our page on why shower pressure drops when a toilet flushes explains that effect.
• A thermostatic valve mixes to a set temperature.
• The limit stop is a small part behind the handle that stops the handle from turning all the way to hot. It is what keeps a curious kid from cranking the shower to full hot.

Tubs that fill from their own spout get a separate rule. Section 412.5 says bathtub and whirlpool tub valves must have or be supplied by a water-temperature-limiting device that conforms to ASSE 1070, or by a water heater that meets ASSE 1082 or ASSE 1084. That device also has to be set so the hot water does "not to exceed 120°F (49°C)."

For a single sink or tub faucet, the code also allows temperature-actuated, flow-reduction devices under ASSE 1062. Section 412.7 says they "shall not be used alone as a substitute" for the required shower valves or tub temperature limiting devices. Treat them as an extra layer, not the main one.

These are rules for new work. A valve installed decades ago may not have a limit stop, or may not balance pressure at all. If your shower jumps hot when someone flushes, or the handle turns to full hot with nothing to stop it, that valve is worth a closer look. Our guide to which Moen shower valve you have helps you identify one common brand.

### Why Phoenix homes should recheck the limit stop in summer

This one surprises people. Moen's Posi-Temp instructions say "Due to seasonal temperature change of the cold water supply, the temperature limit must be readjusted accordingly to maintain the desired maximum discharge temperature." Phoenix's 2025 water quality report lists tap water temperatures from 47 to 92 degrees F. That's a big seasonal swing on the cold side of the mix.

Moen's steps for checking the limit are simple. Turn the handle to the hot stop, "let the water run for several minutes to purge cool water from the hot water supply line," then check the temperature. If it is too hot, the instructions say to remove the handle parts and rotate the stop "clockwise to decrease" the maximum hot water temperature. Other brands use different parts, so follow your valve's own sheet. A thermometer reading at the showerhead twice a year, once in winter and once in summer, tells you where you stand.

### Layer three: hands and habits

The CPSC's last word on scalds is about people, not parts. It says "Never take hot water temperature for granted. Always hand-test before using, especially when bathing infants and young children." It's a small habit, and it is the one layer that never wears out.

Water depth is the other bathroom hazard. The CPSC's in-home drowning sheet says "About two-thirds of the drowning deaths in the home, not including pools, occur in bathtubs." It also says "Toilets are often overlooked as a drowning hazard in the home. The typical scenario involves a child under 3-years-old falling headfirst into the toilet."

The CPSC's tips for the bathroom are direct:

1. 1"NEVER leave a baby alone, or with young siblings, in a bathtub even for a second."
2. 2"Keep the toilet lid down, and keep young children out of the bathroom when unsupervised."
3. 3"Consider placing a latch on the bathroom door out of reach of young children."
4. 4Empty buckets and other containers with liquids right after use. The CPSC calls 5-gallon buckets "a serious threat to toddlers."

Plumbing can back those habits up. Drain the tub as soon as bath time ends, and make sure it actually drains. A tub that takes a long time to empty leaves standing water behind for longer than you think. If yours is slow, why a bathtub won't drain covers the usual clogs and stopper problems. A toilet lid lock backs up the lid-down rule for the day a child is quicker than you.

Kids also flush things. If a toy goes down and the bowl starts to rise, don't flush again. Take the tank lid off and push the flapper closed, or turn the valve behind the toilet clockwise to shut off its water. Our page on a toilet that's overflowing has the full steps.

Two things live there: cleaning products and the shutoff valves.

Chemicals. The CPSC's poison prevention advice is to "Keep chemicals and cleaning supplies safely stored in a locked cabinet or box and out of the reach of children," and to "Keep household chemicals in their original child-resistant containers." If you keep drain cleaner or toilet bowl cleaner in the vanity, add a cabinet lock or move them up high. For clogs, a plunger or a hand snake avoids keeping harsh drain chemicals in the house at all. See safe alternatives to chemical drain cleaners.

Stop valves. Each sink and toilet usually has a small supply valve on the wall below it. Know where they are and make sure they turn. A stuck valve is no help when a toilet is overflowing or a supply line lets go. Our guide on how to shut off water to a fixture shows how to find and test them. If one won't budge or drips when you turn it, replace it before you need it.

Here's the deal. Get the water heater to 120, make sure every shower and tub valve limits the hot side, latch the toilet, keep the tub empty and the cleaners locked. Then check the shower's hottest setting again when the seasons change.

If your valves need a limit stop adjusted, a cartridge replaced or an older valve swapped for an anti-scald model, HQ Plumbing & Air is licensed and insured, and we give free estimates with upfront pricing.