LIMESCALE, the flaky greeny-brown bits that fur up the inside of kettles in hard-water areas, has never really bothered me. It looks a bit of a mess on taps and it impedes the flow of water through my shower-head. But it is a small price to pay for water that "feels" right. Perhaps I have just lived in a city for too long and don't appreciate the more natural things in life.

But hard water can be a real headache for many people. So much so that a reader in Shrewsbury wrote to me asking for help in the "battle" against it. Hard water is rich in calcium carbonate and magnesium sulphate. In themselves they are not harmful or a nuisance.The problem occurs because when water is heated (hot-water tanks, kettles, coffee machines, etc) to above 60 degrees C. Calcium carbonate "precipitates" as a hard crystal - or marble. Other minerals dissolve in hot water but calcium carbonate behaves in an inverse way and turn into limescale.

This can lead to itchy skin through excessive use of soap and detregents, and blocked pipes and damaged heating elements; heating elements become inefficient and energy costs rise. In Yorkshire, where the water is noticeably softer, tea and coffee are delicious and the beer is fuller and sweeter with a creamy head on it that remains all the way to the bottom. Washing takes longer than usual (because the soap takes forever to rinse off) but there is not a trace of limescale around the taps.

There are four basic cures for hard water.
The first involves suspending scale-inhibiting crystals in the cold-water tank. They need changing every six months and are far from satisfactory because they don't treat the problem at source. The second and by far the most expensive is the mechanical water-softener. The devices cost in the region of £500, plus another £50 or so to be fitted professionally, and they require topping up regularly with fresh supplies of salt - about once a month for the average family of four. The disadvantages are that unless the softener is installed at a point beyond the kitchen drinking-water outlet it can be unpleasant to drink. And any run-off of the saline solution that circumvents the main drains could play havoc with garden plants.

Magnetic and electromagnetic water-conditioners can be installed for somewhere in the region of £175. These, also, alter the ionic structure of the water, this time by passing it through a magnetic field. They also use a filter that needs changing a couple of times a year. The laws of nature have a knack of reasserting themselves and in time the system can develop a sort of immunity.

The latest and easiest system to install and maintain is something called the Water-King 1, produced by Lifescience Products Ltd, in Oxfordshire, at a cost of £129.75 ($299cdn). Instead of chemicals or magnetism, the Water-King 1 (also available are models 2 and 3 for larger premises) uses low-frequency radio waves to change the chemical structure of water - and softens it.

The Water-King 1 consists of a small plastic box that contains a microchip and two wire "aerials" that are wrapped around the mains inlet. It is then plugged into a 12-volt power supply and left alone. It is child's play to install and takes about 10 minutes. Running costs are about £2.00 a year.

Gavin Beaumont, of Lifescience Products Ltd, said: "The whole ethos of the company is to treat the probelms in life with low frequencies and radio waves instead of the more invasive things like salts."

It may sound a bit New Age - but I like the idea of the stuff I drink and wash with not coming into contact with any additional salt or chemicals or with some kind of filtration system. Each Water King 1 is sold with a five-year warranty.

I have fitted one to the water supply entering my cellar. It is too early to see any real effect yet, but apparently the low-frequency radio waves are altering the ionic structure of the water. They are actually making it ionically "impure" and therby halting the precipitation of limescale. Instead, the crystals form into white, chalky, translucent dust, which is easily swept along with the flow of water.

"The existing limescale or marble, the hard deposits on anything warm or hot, start to break down and take this new amorphous form of crystal. It loosens up and after a few weeks it can easily be picked off," claims Beaumont.

Jonathan Futrell writing in the Daily Telegraph 1/01/94