What's in your water?

Water in the environment naturally contains bacteria, most of which are beneficial or at least harmless. Untreated water may also contain potentially harmful micro-organisms which are removed or destroyed during the treatment process.

The final stage of water treatment is disinfection. This process uses chlorine to kill any remaining harmful bacteria. A small amount of chlorine remains in the water as it leaves the treatment works to ensure the water remains fresh as it passes through the mains network on its way to your tap.

At some of out treatment works chloramine is used as the extra disinfectant. Chloramine remains in the water longer than chlorine and is mostly used where water travels a long distance.

What about the taste and smell?

We understand that some people don't like the taste or smell of chlorine but we only use the amount necessary to achieve disinfection and only a small residual will reach your tap. An easy way to reduce the amount of chlorine in your drinking water is to pop a jug of tap water in your fridge for a couple of hours -not only will it be nicely chilled, it will also taste good too.

In some areas the taste of chlorine can be more noticeable. This is most often due to how close to the water treatment works you live. The closer you are, the more likely you are able to detect chlorine.

You may also notice that the taste and smell of chlorine is stronger in the morning and at tea time. This is because lots of people are using water at this time and the water is travelling faster through the pipes than at other times.

Some customers occassionally detect a taste in their water that is similar to chlorine and is most noticeable in hot drinks. There are a number of possible reasons for this which our factsheet explains in more detail.

Download Chlorine and chlorine-like taste and odour problems factsheet (310 kb)

The addition of fluoride to water supplies (known as fluoridation) is supported by some health professionals as a good way to protect our teeth from decay. We don't fluoridate any of our water supplies.

There's virtually no lead in our water supply but there may be traces in your tap water if you have a lead supply pipe which connects our mains to your property. Lead water supply pipes are more common in older properties, as is internal lead plumbing which can also be a cause.

Lead is also present in some types of solder used for joining copper pipes. The lead from these pipes and fittings can dissolve into the water and result in raised levels of lead in the water from your tap. Installation of lead plumbing and use of lead solders have been prohibited by Water Fittings Regulations (formerly known as Water Byelaws) for many years.

What are the standards?

Standards are set for lead in drinking water because it's recognised that the intake of lead from all sources should be minimised for health reasons. The UK water quality standard for lead, based on the European Union standard, was reduced in December 2003 from 50µg/l (parts per billion) to 25µg/l and will be reduced further to 10µg/l in 2013. This is in line with the World Health Organisation's guideline value of 10µg/l.

How do we perform?

Modification of the treatment process (known as plumbosolvency control) reduces the amount of lead dissolved from pipes. Since 1995 we've installed this treatment at almost all of our treatment works.

We're already very near to full compliance with the future standard of 10µg/l, with more than 98% of all samples taken at customers' taps complying with this strict standard.

How can we help?

Despite this great improvement in compliance, the removal of lead pipes and fittings is the best way of removing all risk of elevated levels of lead in your water. If you believe that you've got lead pipes or that solder containing lead may have been used in your plumbing and you're concerned about the possible health risks, you can contact us by phoning 0845 1 24 24 24 and request samples to be taken.

For further information regarding the replacement of your lead pipework, please click here to download the guide to lead replacement and the application form. Please contact us on 0845 1 20 84 82 if you require any further information or assistance filling in the application form.

We advise that if water has been standing in lead pipes for long periods (for example, overnight) you shouldn't use it for drinking, cooking or preparing babies' feeds. About 1 gallon/4.5 litres (or half a washing-up bowl) should be flushed from the kitchen cold tap before use, or less if water has been drawn recently from other taps or by flushing the toilet.

Some metals occur naturally in many water sources as they are present in the soil or rock which rainwater passes through. Aluminium and iron compounds are also used at some treatment works as "coagulants" to remove impurities, but these materials and the natural material present are effectively removed by the treatment processes.

Nitrate in water supplies arises from both natural sources and from the use of fertilisers in agriculture. Any nitrate not taken up by crops is likely to be dissolved in rainwater and either percolates down into groundwater or runs off into streams and rivers.

Pesticides covers a wide variety of different chemicals including insecticides, herbicides, fungicides and algicides. They are present in the environment mainly due to their use in agriculture, industry and by Local and Highway Authorities. If you use pesticides in your home or garden please be careful to dispose of any remains safely.