Burns and scalds Hot tap water

Hot tap water can seriously burn your child. Children are more at risk for tap water scalds because:

• A child’s skin is thinner and more sensitive than an adult’s skin. A child’s skin burns more quickly, so even a very short exposure to water that’s too hot can cause a serious burn. 
• Young children can’t move away from hot water quickly. Many tap water scalds happen when a child is in the bath or playing at the sink. Bath water temperature for younger children should be no hotter than 38 °C.

As well, older adults and people with certain disabilities or medical conditions (such as diabetes) are also at high risk for tap water scalds. This is because their skin may not be able to feel heat quickly or because they can’t move away from hot water quickly.

Tap water scalds can happen anywhere that the water is too hot – not just in the bath. Children have been scalded by hot tap water when playing at the sink, or by putting their hands or feet into a bucket filled with hot tap water for household cleaning.

How to check the water temperature in your home

• Use a thermometer that can show high temperatures, such as a meat or candy thermometer.
• Run the hot water tap for two minutes. Make sure the tap is turned to the hottest setting. If you have used a lot of hot water in the past hour, wait two hours before you do this test.
• Fill a cup with the hot water. Put the thermometer in the cup. Wait 30 seconds and look at the temperature. If it is higher than 49 °C (120 °F), you need to lower your water temperature.
• You can also use a special testing card for hot tap water. These are available from some public health offices.

How to lower the temperature of hot tap water

Lower the temperature of your water heater

The easiest way to prevent burns from hot tap water is to turn down the setting on your hot water heater to 49 °C (120 °F). Do this only if you can easily see the thermostat dial on the outside of the tank.

• Read the manual for your water heater before changing the setting on the thermostat dial. If you don’t have a manual, contact the company that made the water heater. Their number should be posted on the heater. If you rent your water heater, contact the rental company.
• Gas– and oil–fired water heaters have thermostat dials located on the outside of the tank. If the dial has numbers on it, turn the dial down to 49 °C or 120 °F. If the dial has words like Hot, Warm (or Medium) and Vacation, turn the dial to the Warm or Medium setting. That is approximately 49 °C (the water will still feel quite hot at your taps but will not cause a scald burn in seconds).
• Do not lower the temperature of your water heater below 49 °C or a Medium setting. A lower setting can lead to the growth of the bacteria that causes Legionnaires’ disease.
• After adjusting the temperature, wait 24 hours and then test the temperature of your tap water again using a thermometer. Sometimes a heater requires several adjustments before you get the right temperature.
• Water heaters may continue to pose scalding risks, even when turned down. Be sure to practise safe bathing and to supervise children closely.
• If you have an electric water heater, don’t lower the temperature setting below 60 °C. The bacteria that causes Legionnaires’ disease grows more easily in some electric water tanks because of the way they are designed. You can still lower your water temperature by installing safety valves. Talk to a qualified plumber, the company that made your heater or the rental company for your water heater. Any adjustments to electric water heaters should be done by a qualified professional.

Install mixing valves

Mixing valves or tempering valves can be installed in the plumbing pipes at various places. These valves control the temperature of the water before it leaves your taps. Inside your water heater, the temperature can be scalding hot, but the valve will mix in cooler water if needed to ensure that water at the tap is no hotter than 49 °C.

Talk to a qualified plumber or the rental company for your water heater for proper installation of mixing valves. The cost of installing mixing valves will depend on how many you install and whether there is other plumbing work or renovations going on at the same time. One valve may cost in the range of $100 to $150, not including labour.

There are three ways you can use mixing valves:

• You can install a master mixing valve right at your water heater. This will control the tap water temperature everywhere in your household.
• You can install mixing valves in the hot water pipes that go to separate areas of your household – for example, to the bathroom and kitchen.
• You can install mixing valves at individual taps – for example, at each sink and bathtub.

In apartments or multiunit buildings

• Turning down the thermostat of large water heaters in multi–unit buildings is not recommended. Harmful bacteria can grow in large water heaters set too low. Also, there may not be enough hot water for everyone in the building.
• Ask your landlord or property manager to make sure that the hot water at your taps is no hotter than 49 °C (120 °F).
• One option is to install mixing valve(s) in the hot water pipes so that the hot water is a safer temperature everywhere in your apartment. An alternative is to install a mixing valve at each of the taps in your kitchen and bathroom.
• If you can’t get mixing valves installed in your hot water pipes, you can use other devices to help protect from tap water scalds.

Other devices to prevent tap water scalds

Anti-scald or shut-off devices

• These products attach to the faucet or tap. Some models actually replace the faucet.
• If the water gets too hot, these devices slow down the water to a trickle. You can restart the water by mixing more cold water into the tap.
• Anti-scald devices are available in safety specialty shops, some hardware stores, and some children’s product stores. They cost about $10 to $50, depending on the type of product.
• Not all models fit on all kinds of taps, however, and although these products are promoted as “do it yourself” items, they may require adapters or the help of a plumber to install them.

Tap guards

A tap guard blocks your child’s access to the hot water tap. These can be found in many home improvement and child safety stores.

Health concerns from lower water temperatures

Risk of bacterial growth – particularly legionella

Legionella is the organism that causes Legionnaires’ disease, a form of severe pneumonia. These bacteria live naturally in ponds, streams and rivers, and also grow in indoor plumbing systems – mostly in hot water tanks.

Many things affect how much legionella will multiply and whether they create a health risk for people. These factors include:

• The temperature and mineral content of the water.
• The type or design of the water heater.
• Whether people in the household are healthy or sick.

Legionella does not pose a risk to drinking water. To make someone sick, the bacteria must be inhaled through water droplets. Many people have been exposed to legionella and do not get sick.

Don’t lower the thermostat of your household water heater below 49 °C as legionella grow best when the inside of the heater is less than that temperature. Note the exception for electric water heaters, which should be maintained at 60 °C.

If anyone living in your home has a long-term or serious illness, check with your doctor before turning down your water heater. 

Do not lower the thermostat setting of your water heater if anyone in your home has health conditions such as:

• A weak immune system (from disease, from taking medicine that suppresses the immune system or from being quite elderly)
• An organ transplant
• Cancer
• Chronic obstructive pulmonary disease
• HIV/AIDS

Controlling dust mites that cause allergic reactions

These mites commonly live in household textiles such as bed sheets, clothing and curtains. Asthma Canada recommends that clothing and bedding be washed in water at least 55 °C to kill dust mites and their allergens.

Instead of using very hot water throughout your home, there are several options.

• A dust mite control additive can be used in a low-temperature wash.
• Dust mites will also be killed by drying fabrics at a high setting for one hour.
• If you need to use very hot water for laundry in order to kill dust mites, you can still lower the hot water temperature in all other areas of your household. Mixing valves to control hot water temperature can be installed in the hot water pipes for all areas except the clothes washer. 

Effective dishwashing, cleaning and bathing

Washing dishes

Makers of dishwashers and detergents often recommend that hot water should be 60 °C for their products to work effectively. However, tests show that dishwashing detergents will perform with good to excellent cleaning results at temperatures as low as 38 °C.

When dishwashers operate with hot water at 49 °C, some water spotting on dishes may occur. Parachute suggests that preventing scald burns from too-hot tap water should have higher priority than the need for spotless glasses. You can wipe glasses with a clean dish towel to remove spots.

As an alternative, many newer models of dishwashers have internal temperature boosters. Incoming water is heated quickly to help clean the dishes. This feature adds about $45 to the price of a dishwasher.

Household cleaning and bathing do not need water temperatures hotter than 49 °C.

• Comfortable bath water is between 37 and 40 °C for adults, and no hotter than 38 °C for younger children.
• Although a lower temperature may have caused problems with washing clothes years ago, newer styles of washing machines and laundry detergents are effective with hot water at 49 °C or cooler.
• In the kitchen, you can kill germs on cutting boards and other surfaces with a mild bleach solution – 1 tsp (5 ml) of bleach in 750 ml (3 cups) of water. The Canadian Food Inspection Agency recommends this process, on top of regular cleaning with hot, soapy water.

Save on energy costs

According to Environment Canada, hot water tanks account for 14 per cent of home energy use. Only home heating uses more energy. Lowering the setting of your hot water heater from 60 °C to 49 °C will reduce your heating bill, but some of this saving may be offset by an increase in the amount of hot water you use. In the end, you will likely see modest savings, in the range of $30 to $40 per year, possibly higher if energy costs rise.

Insulating your hot water tank can also save up to 10 per cent on your energy use for heating water.

Provincial building regulations

As of Sept. 1, 2004, the Ontario building code requires that hot water at household taps be no hotter than 49 °C. The code change applies to new construction and substantial changes to existing plumbing, such as the replacement of water heaters or hot water faucets.

For Quebec, see Prevention of scalding and legionellosis associated with hot tap water in private homes.