Chlorine has been added to water for many years to provide microbiological disinfection. It is added as either a gas or a liquid at very low levels, typically less than 1 part per million (1mg/l). As chlorine is an oxidant it effectively burns the cell walls of bacteria which kill them. The impact of chlorinating public water supplies should not be underestimated; it stops people dying of medieval diseases. Globally, it has made a huge impact on improving public health.
Fluoride is added to public water supplies as evidence suggests it helps improve dental health in children, particularly in deprived areas. However, most of the UK public supplies are not fluoridated. Depending on geology, some private water supplies contain elevated fluoride. Excess fluoride can be associated with calcium uptake problems in the body.
Lead in drinking water is usually caused by either lead pipe work or lead solder in domestic plumbing; it is rarely found at significant levels in public or private supplies. Older properties may be served with a lead service pipe and in some situations, particularly local authority housing, several houses may be served by a single common lead pipe. Lead is a heavy metal, at high levels it is toxic and can be associated with neurological disorders. While it is undesirable to have lead in contact with your drinking water supply, if the pipe work is in good condition it should not leach lead into your water; however, if a lead pipe is poorly installed (shallow buried/un-insulated/subject to shock) or recently disturbed, it may release lead into the water in the form of particulate. When identified it is generally good practice to replace lead; this eliminates any doubt about adverse health effects (and also greatly reduces the risk of leaks/bursts).
Water that is described as hard has high levels of dissolved minerals such as calcium and magnesium. When heated, the minerals can form a solid residue and cause limescale deposits. This can cause problems in any system that heats the water, including kettles. The minerals and limescale are completely harmless to human health and in fact there is evidence to suggest that areas supplied with hard water have lower rates of heart disease. To help limit the problems associated with hard water, salt based softeners are sometimes used. It is generally considered poor practice however to soften water used for drinking and food preparation. Problems associated with hardness may also be managed by regular de-scaling of affected equipment and in some situations, reducing the operating temperature of water heating devices.
Mains Water Quality
Mains water quality in most countries is excellent and the UK is no exception. The water supplied has to comply with stringent regulations and the production of it is monitored and sampled around the clock. Products that claim to remove ‘harmful contaminants from mains water such as chlorine and lead’ are common and very misleading. In most situations the products themselves are not approved for use in contact with mains water and often reduce the quality of mains water.