What's in your water?

Interested in what's in your tap water and how it gets there?

You'll also find details below about what affects the hardness of the water in your home, the presence of things like calcium and fluoride, and the processes that are in place to make sure your drinking water is kept safe and clean.

Although it's our job to get the water from its natural source and safely into your home, there are things you can do to ensure that the water you drink, cook with and wash in is of the very best quality. This easy-to-read guide from the Water Regulations Advisory Scheme (PDF 5,574 KB opens in a new window) will help, too - it tells you how you can have control over the condition of your own tap water.

Water hardness

The hardness of water is due to the presence of calcium and magnesium minerals that are naturally present in the water. The usual signs of a hard water supply are scaling inside kettles, poor lathering of soaps, and scum.

The majority of raw water in the North West comes from upland surface water reservoirs which are soft or very soft. We do use water from a number of boreholes in the south of the region that are reasonably hard, but these tend to be blended with softer sources to meet demand.

If you are interested in hardness for your dishwasher or washing machine, visit our water quality page where you can get this information quickly and easily. The factsheet on water hardness, which you can access below, can be used get the conversion tables you might need for your appliance.

Hard water can be softened by the installation of a water softener or the use of ‘jug type’ filters. Medical experts recommend that a non-softened supply is maintained for drinking purposes because softened water may contain high levels of sodium. Softeners should be fitted after the drinking water tap and comply with the requirements of the Water Supply (Water Fittings) Regulations 1999. They should be maintained in accordance with manufacturers’ instructions. Further information and advice about water softeners can be found on the Water Regulations Advisory Service website.

For more information, please take a look at our factsheet on water hardness (PDF 45 KB opens in a new window)


Fluoride occurs naturally in most water supplies, though the actual amount present varies depending on the source. Some water supplies can contain fluoride if they originate from sources underground where there are rocks that contain fluoride-rich minerals.

Water supplies in the North West are naturally low in fluoride - and normally contain less than 0.2mg fluoride per litre.

Some water supplies have fluoride added to raise the concentration to 1.0mg per litre. This figure includes the fluoride that was already there naturally.

Why is fluoride added to water?

Fluoride is added to the water supply at the request of a health authority because a small amount of fluoride in the diet strengthens the enamel on teeth, especially in children.

Who decides where fluoridation takes place?

A health authority can direct a water company to fluoridate the water supply in an area if it is technically possible, but they must consult the public first before introducing any new schemes. The water company acts as a contractor and cannot refuse to fluoridate the supply if directed to do so.

On April 1 2013, the Secretary of State for Health became responsible for existing fluoridation schemes via Public Health England, and local authorities became responsible for proposing and carrying out consultation on new schemes and extensions to existing schemes.

Questions about existing fluoridation schemes can be addressed via the Public Health England area on the GOV.UK website. Any questions on possible future fluoridation schemes in your area should be addressed to your local authority.

Where does it happen now?

Agreements are in place between Public Health England and United Utilities which require artificial fluoridation at three of our water treatment works. Two of these works are in West Cumbria, at Cornhow and Ennerdale. The third is at Hurleston, in Cheshire. The agreements for fluoridating these supplies date back to the early 1970s.

Cornhow's works supplies water to Workington, Seaton, High Harrington, Great Clifton, Silloth, Maryport, Flimby and Cockermouth. Ennerdale's works supplies water to Whitehaven, Arlecdon, St Bees, Frizington, Salterbeck, Egremont, Cleator Moor, Beckermet, Ravenglass and Bootle in West Cumbria. Hurleston Water Treatment Works supplies water to Crewe, Alsager and Nantwich.

The population served from these water treatment works is a very small fraction of the total population supplied by United Utilities.

What is the process for introducing new fluoridation schemes?

The Water Act 2003 was given Royal Assent in November 2003. This legislation states that a health authority can direct a water company to fluoridate the water supply in an area, if it is technically possible. The authority must consult with the local community and businesses in the affected area. The water company will act as a contractor in any new schemes and cannot refuse to fluoridate the supply.

On April 1 2013, the Secretary of State for Health became responsible for existing fluoridation schemes and local authorities became responsible for proposing and carrying out consultation on new schemes or extensions to existing schemes. Any questions on possible future fluoridation schemes in your area should be addressed to the local authority where you live.

Who pays for fluoridation?

The health authority meets all costs associated with fluoridation of the water supply. This includes the cost of the chemical, maintenance of the equipment, monitoring and any additional sundry costs. The fluoridation of water does not have any impact on customers' bills in the region.

For more information, please contact us on us on 0345 672 3723. Dial 18001 first if you have hearing or speech problems.

How is fluoridation carried out?

There are currently two chemicals approved for the artificial fluoridation of water: these are disodium hexafluorosilicate (Na2SiF6) and hexafluorosilicic acid (H2SiF6). United Utilities uses hexafluorosilicic acid for its existing schemes. All products and processes that come into contact with drinking water must be approved. A list of all approved products and processes can be found on the Drinking Water Inspectorate (DWI) website. The chemicals are generally added at the water treatment works. We must follow strict guidelines laid down by the Government detailing how water should be fluoridated artificially.

The fluoride concentration is continuously monitored as the water leaves the water treatment works. The maximum permitted concentration of fluoride in drinking water is 1.5mg per litre (1.5 parts per million).


Lead is a metal commonly found in the environment. In the past, it was used widely in paint, as a petrol additive, and for plumbing materials. Lead is not used for water pipes anymore but properties built before 1970 may have lead pipes somewhere between the tap in the kitchen and the main in the street outside. Water that leaves our treatment plants contains virtually no lead. However, it may pick up lead as it passes through lead pipes.

Lead can be harmful to health if you are exposed to it over time. Children under six and babies are particularly at risk because of the possible effect on mental development. Lead can also be passed to the unborn child so pregnant women are at risk. The Government advises that people should minimise their exposure to lead from all sources, including drinking water.

The most effective way to reduce your exposure to lead from drinking water is to replace the lead pipework between the external stop tap and the kitchen tap. If you do this, we will replace the length of lead pipe that is our responsibility, free of charge.

Here are some simple short-term measures you can take to reduce the amount of lead in the water used for cooking and drinking:

  • ­use only cold water – boiling will not remove lead
  • if your tap has not been used for some time e.g. overnight, run the tap to flush out water that has been standing in the pipes. In most circumstances, you only need to fill a washing-up bowl. Don't waste this water – it can be used for other things, like watering plants. Please note, you will need to flush the tap for longer if your property is more than 50 metres from the main. As a guide, 10 metres of pipe holds 1.2 litres of water. It is not possible to completely flush out very long supply pipes (pipes greater than about 50 metres) and in these circumstances you should give serious consideration to having the lead pipework replaced
  • if you decide to give infants bottled water, or use it for preparing infant formula, ensure that it contains less than 200mg per litre of sodium, sometimes written as ‘Na’. Check the bottle label for details
  • filters are available to remove particulate lead, which are useful if your water contains lead-rich particles. However, to be effective, filter devices must be used according to manufacturers’ instructions
  • when installing new plumbing or repairing or modifying existing plumbing, always use lead-free solder­
  • avoid disturbing or knocking lead pipes. Such mechanical action can generate particulate lead
  • do not lay hot water pipes alongside or close to cold water pipes


pH is a measure of acidity or alkalinity. The water quality regulations specify that the pH of tap water should be between 6.5 and 9.5. Water leaving our treatment works typically has a pH between 7 and 8, but this can change as it passes through the network of reservoirs and water mains.

If the pH of your water has changed, and yours is the only property affected, the source will be your internal pipework and plumbing. Possible sources include plumbed-in water filters or softeners, incorrectly installed washing machines or dishwashers, incorrect fittings and taps supplied from storage tanks. If you have had any recent work carried out on your plumbing then excessive use of solder or flux could be the cause. In this case the problem may improve over time, or you might want to consider changing the pipework or joints.

There are no health risks associated with consuming water that is slightly acidic or alkaline. After all, we can eat lemons and drink soft drinks. However, when the pH of the water is much lower than the standard it can lead to metals from plumbing and fixtures in properties to be released. This could cause a health problem. In these circumstances the water may have a slightly bitter or metallic taste. If the pH of your water is too high, it will have a taste similar to baking soda and have a slippery feel to it. It will also begin to leave scale deposits on plumbing and fixtures.

For more information, please take a look at our factsheet on pH (PDF 47 KB opens in a new window) .