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Britain is supplied tap water by about 30 different regional companies, and these supply us with about 20 billion litres every day.
A recent report from The Drinking Water Inspectorate (the government department enforcing quality) showed that 99.78% complied with legal standards.
Indeed, while we might grumble, a survey of London foreign visitors thought the tap water there was better than their own.
Since the early 1990"s there have been some dramatic improvements in some of the areas that gave concern at the time. Take pesticides, for example, a quarter of the supply zones in England and Wales then failed one of the two tests on this count - now failure rates are down to less than 2%.
However, throughout the country there have been wide discrepancies. York, has habitually suffered high levels of the pesticide Isoproturon; and the Sutton area of Surrey, where nitrites - linked with farm run-off and implicated in stomach cancer - exceeded limits in 20% of tests.
Most of the recently imposed European standards are tighter than our own - so things should improve further. For example, the outgoing UK standard for lead was 50 microgrammes per litre, this is being reduced to 10 microgrammes by the end of 2013.
Cryptosporidium - a bug that causes severe diarrhoeal illness, lasting two to three weeks, which in "immuno-compromised" groups, such as AIDS sufferers, can be fatal. Cryptosoridium can survive for long periods in pipes and reservoirs; and although it"s likely that it"s always been with us, we now have the capacity for detailed scientific scrutiny and there have been over 30 significant outbreaks linked to water since 1988.
Another area for concern comes in the form of host chemicals - some now known to be toxins, but previously thought of as harmless. Some of these have the potential to disrupt our endocrine processes (these control everything from our reproductive and immune systems to our personality). At least 50 such "gender-bending" chemicals, from sources such as plastics, food packaging, sewage and industrial effluent, have been identified. Activated carbon-filtration systems installed in water-treatment plants in the 1990"s (to strip out pesticides from river water) should also help to mop up endocrine disrupters - although nt enough is currently known.
Unfortunately, as taxpayers we have spent billions subsidising farmers to douse their fields in chemicals, then billions in our water bills to try to take them out.
Although chlorine has been useful since Victorian times, there are now also elements of doubt into its safety. Its by-products - trihalomethanes, for example - are known to cause an increased risk of cancers of the bladder, colon and rectum. It"s also ineffective against Cryptosporidium and Giardia lamblia - another parasitic bug that causes diarrhoea and nausea.
The Drinking Water Inspectorate aren"t keen on jugs with added filters, as unless these are changed regularly, the filters can serve as breeding grounds for bacteria. They recommend putting a covered jug of tap water in the fridge for half an hour to let the chlorine evaporate and claim it will taste as good as bottled water.
Viable alternatives to chlorine, such as ultraviolet light and ozone treatment, are now available, both for drinking water and swimming pools. Cities now disinfecting their drinking water without using chlorine include Amsterdam, Paris and Munich. See 'Water; Mineral'