Making hot water safe water

Published:  03 July, 2008

About 500 children, the vast majority aged under five, are admitted annually to hospital in the UK with a severe scald caused by bath water

There is absolute no need for scalding accidents associated with domestic hot water, as Martin Strom explains.

The dangers of scalding hot water in bathrooms are widely recognised, and the solution appears, at first glance, to be simple — test the water temperature first. Yet we frequently hear of scalding accidents where care-home residents were severely or fatally scalded in a bath or shower. How can this happen?

Hot bath water is responsible for the highest number of fatal and severe scald injuries in the home. Every year around 20 people die as a result of scalds caused by hot bath water, and a further 570 suffer serious scald injuries.

The degree of scalding depends on the temperature and volume of hot water, and the length of time the body is exposed to it. It can take only seconds for a severe scald to occur.

As adults we have all pulled back from water that was too hot at some time, but children and the elderly are at particular risk of life-threatening scald burns.

The elderly are at increased risk because their skin tends to be less sensitive, and they are less agile. For both reasons, they might not be able to pull away from hot water quickly enough to avoid scalding. People with a reduced ability to perceive risk or react to hazardous situations, for example those with mental or physical disabilities, are also at greater risk of injury.

About 500 children, the vast majority aged under five, are admitted annually to hospital in the UK with a severe scald caused by bath water. Tragically, some die. A further 2000 suffer less severe scald injuries. A few seconds’ lapse can damage a child for life. Severe scalds can result in long-term disability and disfigurement, and can be among the most distressing and painful injuries a child can receive.

Those with mental or physical disabilities are also at greater risk as they are more likely to have a reduced ability to perceive risk, are unable to sense excessive temperatures or to react to hazardous situations.

Even if carers follow advice to test the water temperature first with their elbow, there is the possibility that the bather will then add more hot water — intentionally or accidentally — when the carer’s back is turned. Taking that a stage further, how can we therefore trust vulnerable people bathing alone to take the required amount of care while completely unsupervised?

In October last year the Health & Safety Executive (HSE) warned nursing care homes that should follow HSE guidelines to avoid scalding hot water in bathrooms. The warning followed the prosecution of care home managers whose staff placed an elderly resident in scalding hot water, causing fatal injuries.

Fail-safe

Simple technology to prevent scalding water is available. Many care homes and local authorities have voluntarily fitted thermostatic mixing valves (TMVs). These fail-safe devices blend the hot and cold water supplies to deliver it at a safe preset temperature. Unlike simple mixer taps, TMVs maintain the outlet water temperature irrespective of the incoming hot water temperature and flow rate. If the cold water supply should fail, the thermostatic mixing mechanism will automatically shut down the flow to prevent discharge of dangerously hot water.

Mary Creagh, the MP for Wakefield, has campaigned long and hard for laws requiring TMVs on all new baths to prevent scalding hot water from taps. Her campaigns have drawn much discussion on radio, TV and in the national press. Most authorities and members of the public agree that bathroom scalding is totally preventable.

TMVs make sense, but why is water stored and delivered in building at a scalding temperature anyway?

The problem of scalding water has become more acute in communal and public buildings in recent years because high temperature is the preferred method of controlling legionella bacteria. Hot water is stored at at least 60°C and distributed at a minimum of 50°C. This temperature is dangerously hot for bathers, so there must be fail-safe mixing control at the outlet to prevent scalding. In care homes, a TMV should be set to deliver hot water at 43°C.

TMV standards

For ease of installation, Honeywell thermostatic mixing valves can be supplied with tailpieces incorporating isolation, strainer and test points.

Legislation exists requiring thermostatic mixing valves certified to Buildcert TMV3, to be fitted to basins, baths and showers in NHS hospitals. TMV3 approval is granted if a TMV complies with the requirements of NHS specification D08.

However, their fitting is only recommended in NHS and private nursing care homes, and private hospitals.

A second class of TMV is the domestic TMV2 standard. These are acceptable for most premises that are neither medical nor caring establishments, but a risk assessment should be carried out to determine if facilities are used by vulnerable people, such as young children, the elderly or mentally or physically disabled. If so, TMV3 valves should be installed to provide the maximum safety level. As young people are also at greater risk of scalding, premises such as young persons’ care homes are required by law to fit valves to the TMV3 standard.

Suggested best practice is for TMVs to be installed in all buildings, even if there are no specific recommendations or requirements, unless a risk assessment has concluded that it is safe not to use TMV control. This assessment is based on the risk to the user and the capability, whether mental or physical, of the user to avoid being scalded. The relevant authority or controlling body should be consulted for the particular building.

Water Supply (Water Fittings) Regulations 1999 Guidance Document paragraph G18.5, issued by Defra, states: ‘Terminal fittings or communal showers in schools or public buildings, and in other facilities used by the public, should be supplied with water through thermostatic mixing valves so that the temperature of the water discharged at the outlets does not exceed 43°C.’

Making a selection

TRVs employ a temperature-sensitive element that controls the hot and cold water inlets to provide a safe uniform temperature. Choose valves that cut off the hot water inlet automatically if the cold supply fails and for WRAS approval for use with attended and unattended high pressure baths, as well as high and low pressure hand basins, bidets and showers.

Ensure the valve cap (which displays the temperature set point) is lockable to prevent unauthorised adjustment, as shown in the photos. Choose a valve designed for convenient installation under a bath or basin. To overcome any space restrictions there is a flexible connector and isolating filter valve for the valve. There are models with tailpieces that incorporate isolation, strainer and test points.

The devices illustrated in this article comply in these respects.

More information

BRE Information Paper IP14/03 includes a useful table showing, for various establishments and different types of appliance (bath, shower, or basin), whether a TMV is required by legislation or authoritative guidance, is a recommended option, or is suggested as ‘best practice’.

Free advice on selection and installation of TMVs is available from the Honeywell Technical Support Line during office hours on 08457 678999.

Martin Strom is business manager for water products with Honeywell Environmental Controls.

Access space for thermostatic mixing valves will often be restricted, a problem that can be overcome by devices such as Honeywell’s TM200VP with optional isolating filter valve and flexible connector.


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