Hot water from the bathroom tap can burn skin much faster than most people expect. Young children and older people are at the greatest risk. The good news is that a few simple steps at home can lower that risk a great deal. A bathroom renovation is also an ideal time to look at how hot your water runs.
This guide explains how scalds happen, what tempering valves do and the daily habits that help. It draws on guidance from the Victorian Building Authority and The Children’s Hospital at Westmead. Plumbing rules and older systems vary across Australia. Always ask a licensed plumber about your own home.
How quickly hot water burns
A scald is a burn caused by hot liquid, steam or gas. The Children’s Hospital at Westmead says water at 65°C can cause a full thickness burn in under one second. At 60°C the same injury takes about five seconds. At 50°C it takes about five minutes.
Those few degrees make a huge difference. A child who slips in a bath or grabs the wrong tap has very little time to react. The VBA notes that elderly people and people with a disability are also at higher risk. Lowering the temperature at the tap buys precious time.
The hospital also notes that most scalds to children happen at home. Hot drinks, hot food and cooking are common causes, along with bathwater from the hot tap. The Victorian Building Authority hot water safety guide says over 90 per cent of hot water scalds happen in the bathroom. That makes the bathroom the best place to start.
Why stored hot water is kept so hot
It might seem simple to just turn the heater down. However, the VBA explains that hot water is stored above 60°C to prevent bacteria such as Legionella. That means the water in the tank needs to stay hot. The answer is to cool it on the way to the bathroom rather than in the tank.
This is where the choice of hot water system comes in. Some homes run on gas, others on electric or solar heating. Each type still stores or heats water to a high temperature. If you are weighing up energy sources, our article on solar energy vs fossil fuels for your home looks at the bigger picture.
What a tempering valve does
A tempering valve mixes hot and cold water before it reaches the tap. The VBA says it means water comes out of the tap at a lower temperature, while the stored water stays hot. It reduces bathroom temperatures but does not affect the kitchen. That way you still get very hot water for washing dishes.
Thermostatic mixing valves are another option. The VBA says these can be set to deliver hot water at a precise, safe temperature. Continuous flow systems often have electronic control pads. These can be set to a safe preset temperature.
The VBA states that plumbing rules require a maximum of 50°C at each shower head or tap outlet. Schools, early childhood centres and nursing homes have a lower limit of 45°C. These figures come from the Victorian regulator. Rules and their dates can differ between states, so check with a plumber where you live.
Older homes and renovations
Many older homes were built before tempering became standard. The VBA says hot water systems installed before 5 August 1998 are unlikely to have tempering. If your home has an older system, it may be delivering water much hotter than 50°C to the bathroom. A licensed or registered plumber can check this and fit a valve if needed.
A bathroom renovation is a natural moment to sort this out. The walls are open, the plumbing is being reworked and a plumber is already on site. Ask about the outlet temperature and whether a tempering valve or mixing valve suits your system. It is often easier to plan this now than to add it later.
Renovations often run through several rooms at once. If the kitchen is also on the list, our article on refacing or replacing kitchen cabinets weighs up the options. Remember that a bathroom tempering valve will not change the kitchen tap. Hot water at the kitchen sink still needs care around children.
People planning to stay in their home as they get older often think about safety in the bathroom. Lower water temperatures pair well with grab rails and step free showers. Some families also look at moving between floors more easily. Our guide on choosing a home lift installation company covers that side of things.
Everyday habits that lower the risk
A valve helps, but daily habits matter just as much. The Children’s Hospital at Westmead suggests several simple steps for families with young children. They are easy to build into the bath time routine. Most cost nothing at all.
- Never leave young children alone in the bathroom, or in the care of an older child.
- Run the cold water first, then add hot, and turn the hot tap off first.
- Check the water before a child gets in, ideally with a bath thermometer.
- Keep bathwater for small children at or below 40°C.
- Close the bathroom door when the room is not in use.
- Silence your phone before running a bath so you are not distracted.
The hospital says testing with your inner wrist or elbow is a useful guide. A bath thermometer is the most accurate method though. The VBA gives 37 to 38°C as a bathing temperature for young children. Child resistant taps can stop little hands turning the tap, but they do not lower the water temperature.
Bathroom floors also play a part, as wet surfaces can lead to slips near hot water. Outside the bathroom, softer floors suit play areas and bedrooms. Our article on carpet types and cleaning looks at flooring choices for the rest of the house. Keep hard, easy to dry surfaces for the wet areas.
First aid for a scald
The Children’s Hospital at Westmead fact sheet on hot water and scalds advises running cool water over the burn for 20 minutes. This stops the burning and cools the skin. It can still help if started within three hours of the injury. Call emergency services or seek medical help if you are unsure how serious the burn is.
Some old home remedies can make things worse. The hospital says not to apply ice, iced water, creams, toothpaste or butter. Burn creams do not cool the skin, so they should not replace cool running water. Keep this advice in mind and share it with anyone who looks after your children.
Frequently asked questions
What temperature should bathroom hot water be?
The VBA says plumbing rules in Victoria require a maximum of 50°C at each shower head or tap. Rules can differ between states. Ask a licensed plumber about your home.
Will a tempering valve make my kitchen water cooler?
No. The VBA says a tempering valve reduces bathroom temperatures but does not affect the kitchen. Water at the kitchen sink can still run very hot.
Can I just turn my hot water system down?
Stored hot water is kept above 60°C to prevent bacteria such as Legionella, according to the VBA. That is why it should stay hot in the tank. A tempering or mixing valve lowers the temperature at the tap instead.
Does my older home have tempering?
The VBA says systems installed before 5 August 1998 are unlikely to have tempering. A licensed or registered plumber can check yours. A renovation is a good time to ask.
This article is general information only and is not medical advice. Plumbing rules differ by state and change over time. For a burn or health concern, speak with a doctor or qualified health professional, and ask a licensed plumber about your hot water system.
