Information Leaflet
Water Hardness

1. What causes hard water?
2. What are the problems with hard water?
3. How can I find out if I have hard water?
4. Map of areas of hard and soft Water
5. Is there a standard for the hardness of drinking water?
6. Should I use a water softener?
7. Magnetic and Electrical conditioning devices
8. Where can I get more information about drinking water quality?

Drinking water in England and Wales is of a very high quality but some people are concerned about whether they have hard water. This leaflet answers the questions most often asked about hard water.

What causes hard water ?

Water that is hard contains calcium and magnesium compounds. Rain water is naturally soft - it does not contain any minerals, but as it seeps through the ground it can pick up minerals, such as calcium and magnesium compounds, from the soil and rocks it passes through. If rain water passes through soft rocks like chalk or limestone, it picks up these minerals. If it passes through hard rocks, such as granite or through peaty soils, it does not pick up these minerals and so remains soft.

What are the problems with hard water ?

Hard water causes pipes to fur up and scale to collect in kettles and in electric irons and washing machines. If the scale collects on heating elements it shortens their life and makes appliances less efficient. It is also more difficult to work up a lather from soap, washing up liquid and washing powders. It can also cause "tide marks" on basins, sinks, baths and toilets.

How can I find out if I have hard water ?

The map below/overleaf shows generally hard and soft water areas. The map is only an indication because even hard water areas can contain pockets of soft water and vice versa. You can get detailed information from your water company. Enquiry numbers are listed under WATER in your telephone directory.

Is there a standard for the hardness of drinking water ?

There is no maximum value for total hardness of water supplies. There are maximum values for two substances, calcium and magnesium, which cause hard water. In England and Wales all water supplies meet the value for calcium and six supplies exceed marginally the value for magnesium, but as there is no risk to health, a relaxation of the magnesium value has been granted by the Inspectorate for these supplies. Where water companies soften water before they put it into supply, there is a minimum value for total hardness which all the softened supplies meet.

Should I use a water softener ?

This is a matter of personal choice. A softener will improve the efficiency and increase the life of appliances using hot water. It will make lathering easier and reduce tide marks on sanitary ware. Some people with skin conditions, such as eczema, have fewer problems if they use soft water for washing. But if you do install a water softener you should make sure that you have a supply of unsoftened water for drinking and cooking.

This is because:

• there is evidence of less heart disease in hard water areas than in soft water areas, although not all studies find this link. If something in hard water protects against heart disease, water softeners might remove this protection along with the hardness
• many water softeners work by replacing the hardness with sodium. Too much sodium can be a problem for premature babies because their kidneys are not good at filtering it out of the blood, and for people who are on a low sodium (low salt) diet
• soft water may release lead from any lead pipes downstream from the softener
• a softener which has not been properly looked after may release germs into the water.

If you do decide to have a water softener we advise that you buy it from a reputable supplier, for example, one which is a member of British Water, and have it installed by a qualified plumber who is a member of a recognised Trade Association, such as the Institute of Plumbing. We also advise that you maintain it in accordance with the supplier's instructions.

Magnetic and Electrical conditioning devices

Some of these devices have been shown to be effective in reducing the amount of fur or scale that actually sticks to pipes or heating elements. They do not soften water. However, not all products on the market give satisfactory performance. You are advised not to buy one of these devices unless the supplier will agree to a sale or return, subject to satisfactory performance.

Where can I get more information about drinking water quality?

Your water company's public record

You can see the record at one of the company's offices. Customer services staff will explain the result of tests and tell you what is being done to rectify any failures. You are entitled to a free copy of the record for the area in which you live. Alternatively, you can write to the company for details.

Your local authority

Water companies are required to give local authorities information about the quality of water supply in their areas.

Our Annual Reports

These are lengthy reports containing a great deal of detailed information about the quality of drinking water in England and Wales. They can be bought from The Stationery Office. You may be able to see a copy at a main library or at your water company's offices.

Our leaflet "How Good is Your Drinking Water"

This is produced each year and is a brief summary of our Annual Report.