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Hot Water Scalds

Have you ever wondered why some washrooms in restaurants and pubs keep the water temperature so hot that scalding water pours from the taps? In some cases they have notices warning you that you the water is extremely hot. 

So, what is the reason for having such hot water in the first place? The answer is, by raising the temperature of the water stored to 60oC or over, bacteria such as Legionella are killed off. This type of bacteria grows in conditions where the water temperature is between 20o to 45oC degrees. If it is inhaled in the form of water droplets, or vapour, it could develop into Legionnaires’ disease, which is a potentially fatal type of pneumonia. That said, it is extremely rare to contract Legionnaires’ disease through just washing your hands, so don’t be alarmed. 

However, this does show that there is a conflict when it comes to hot water storage. It may be ideal to have water heated and stored at high temperatures to control and kill bacteria, but it can cause severe scalding injuries in a matter of seconds. Likewise, water that is heated and stored at safe non-scalding temperatures provides the ideal medium and temperatures for bacteria growth. It’s a bit of a ‘Catch-22’ situation. 

Scalding injuries are preventable 

In the home, hot water will also be stored at around 60oC, the temperature at the tap is normally around 55oC. If you were to run a bath at that temperature, without adding any cold water, it would only take seconds to get a serious deep tissue burn. The Department of Health recommends the temperature for bathing should be no higher than 43oC and showering at no higher than 41oC. For babies, the temperature should be no higher than 37oC. When running a bath always put the cold water in first and then bring it up to the required temperature. 

When it comes to showering, a thermostatically controlled shower is the best option. Basically, the thermostatic mixing valve (TMV) in the shower takes a hot and cold supply and blends the water to a ‘safe’, controlled temperature at the outlet. Most TMVs also have a failsafe mechanism so if there is a failure with either the hot or cold water supplies the valve will close off. This allows virtually no water to pass through and hence protects the user and at the same time highlights the fact that there is a problem with the plumbing system. 

Lots of homes have manual mixing valves at sinks, washbasins and baths, which are helpful in controlling temperatures, but it must be remembered that temperatures can still fluctuate, especially if there is a drop in water pressure. Always carefully test the water temperature before you get into the bath or before you place your child in the bath. 

The use of TMVs 

In April 2010, revisions to Part G of the Building Regulations (Hot water supply and systems) for England and Wales, included the requirement that baths (subject to Building Regulations) in new build properties are fitted with a protective device (i.e. a thermostatic mixing valve) to limit the temperature of hot water. Similar regulations have been in force in Scotland since 2006. 

This was very widely welcomed by organisations such as The Royal Society for the Prevention of Accidents (RoSPA), who in fact campaigned for the change. If you have an older property and are caring for young children, elderly or vulnerable people who may have mobility problems or other difficulties, it may be worth considering having a TMV fitted for the bath.

However, you should be advised that these devices should be maintained. Always use a professional plumber as he or she will make sure the TMV is fitted so that it can be easily accessed for servicing. 

Hospitals and care homes have to be especially vigilant when it comes to controlling water temperature, as they are caring for young children and vulnerable people. These establishments have to have a different type of thermostatic mixing valve fitted, which are more suitable for their needs. 

Raising awareness 

If more people are aware of the issues surrounding hot water scalds it will help to reduce the amount of terrible injuries suffered at present. The CIPHE supports the ‘Hot Water Burns Like Fire’ campaign and further information on this can be found at 

To see how much you know about the affect of hot water temperatures, why not take part in our short survey

To find a CIPHE registered plumber in your area, please follow this link.