Water UK

Water UK

Water UK represents all UK water and wastewater service suppliers at national and European level. We provide a positive framework for the water industry to engage with government, regulators, stakeholder organisations and the public.

Company details

3rd Floor, 36 Broadway , Westminster , London SW1H 0BH United Kingdom

Locations Served

Business Type:
Professional association
Industry Type:
Water and Wastewater
Market Focus:
Nationally (across the country)

Water UK brings people together to create better policies for the future of water.

We represent all major statutory water and wastewater service supply organisations in England, Wales, Scotland and Northern Ireland. We work at national and European level for a strong water industry on behalf of our members and the interests of all our stakeholders.

Our prime focus is on high-level policy - instigating and facilitating the development of sustainable water policy that ensures lasting economic, social and environmental benefits for the UK.

Our aims are to promote the highest levels of drinking water quality, an environmentally sustainable industry and a stable regulatory regime able to attract the investment which the industry needs.

Who we work with

On behalf of our members, we engage with Defra and with other government departments and with the principal UK regulatory bodies - including Ofwat, the Environment Agency, the Drinking Water Inspectorate and their equivalents in Scotland, Wales and Northern Ireland.

The ever-increasing importance of European law is reflected by our policy work at EU level, and we are active participants in Eureau, the European Federation of National Associations of Water and Wastewater Services. This provides a powerful platform for the industry within the European institutions.

Our structure

Within Water UK, overall policy is set by our member companies, working through a Board and a Council of Members. Detailed policy work is carried out by our staff team, led by our Chief Executive.

The four main areas of work are:

This work is supported by advisers for:

Water UK also provides a wide range of specialist networks and forums allowing our members to exchange best practice and to carry out research on issues of common concern.

Membership of Water UK is open to all businesses authorised to supply water and wastewater services in the United Kingdom, and to the equivalent government or statutory authorities providing these services in Scotland and Northern Ireland. We seek to maintain our ability to represent the whole sector by broadening the membership to include market entrants competing with the established suppliers.

Our partners

Our broader stakeholder engagement programme of industry events and forums is supported by a number of partners, and we continue to develop opportunities for new partners.

It's easy to forget about water after you flush or drain your sink, but wastewater companies put a lot of effort into treating our sewage and ensuring it is returned to the environment responsibly.


Wastewater companies in the UK have an important duty to take away and treat our sewage. At the sewage works, wastewater passes through a set of treatment stages before being safely returned into the environment. Some companies are able to collect energy or other useful materials from the wastewater treatment process. The steps that wastewater companies take when treating our sewage are outlined below.

1. Taking sewage away

When you flush the toilet or empty the sink, the wastewater goes down the drain and into a pipe which takes it to a larger sewer pipe under the road. The sewer then joins a network of other sewers and takes the wastewater to a sewage treatment works.

2. What is the screening process?

The first stage of cleaning the wastewater is to remove objects that should never have been put down the drain in the first place - such as nappies, face wipes, sanitary items and cotton buds - but often can be things like bricks, bottles and rags!

The wastewater often contains a lot of grit that gets washed into the sewer, so companies have special equipment to remove this as well.

3. What is the primary treatment stage?

The wastewater still contains organic solid matter, namely human waste. The next stage is to separate this from the water, and to do this, companies put the wastewater into large settlement tanks, which causes the solids to sink to the bottom of the tank. This is called settled solids or sludge.

In a circular tank, large arms or scrapers, slowly move around the tank and push the sludge towards the centre where it is then pumped away for further treatment.

The water passes over a wall near the top of the tank and is taken to the next stage of the treatment process.

4. What happens at the secondary treatment stage?

Although the visible bits of sludge have been removed, companies have to ensure that the smaller and sometimes invisible nasty bugs are also taken out.

At larger sewage treatment works, the wastewater is put into rectangular tanks called aeration lanes, where air is pumped into the wastewater. This encourages the good bacteria to break down the nasty bugs by eating them. The more they eat, the more they grow and multiply until all the nasty bugs have gone.

5. What occurs in the final treatment stage?

The treated wastewater is passed through a final settlement tank, where the good bacteria sink to the bottom. This forms more sludge - some of it is recycled back to the 'secondary treatment' stage, and the rest goes to sludge treatment. The now clean water passes over a wall near the top of the tank.

Sometimes additional treatment is needed if the river that the treated wastewater will be returned to is particularly sensitive. The treated wastewater is slowly filtered through a bed of sand, which acts as a filter and catches any remaining particles.

6. What is sludge and what treatment process is it put through?

The materials remaining from the wastewater treatment are known as sludge. The sludge collected during the process is treated and put to good use. Most of it is recycled to agricultural land for farmers to use as fertiliser, but companies also use it as a bioresource to generate energy in a variety of different ways, including the provision of heat, electricity and gas.

7. Where does the treated water go?

Once the wastewater is clean, it can be returned to local rivers and streams, or discharged to sea. In some areas, the water put back into the environment can improve water quality in rivers and streams, helping to keep them healthy.

The quality of the cleaned wastewater is strictly regulated by the Environment Agency and Natural Resources Wales, and companies thoroughly test it to make sure that it meets high quality standards.

Discover Water

If you are interested in learning more about the water cycle, or drinking water quality, take a look at DiscoverWater, the industry dashboard.

Water companies consistently provide us all with high quality drinking water. Water goes through a set of treatment stages before coming through to our taps.

Water companies in the UK work hard throughout the year to ensure that high quality drinking water is delivered to our taps at all times. The natural availability of water varies across the UK, so the approaches taken by companies can vary. However, the usual key steps within the delivery of water are outlined below.

1. How is water collected?

The water that comes out of our taps starts off as rain. This rainwater is collected in reservoirs via rivers and streams or filters through the earth to form 'groundwater'. Water companies then pump this water to their water treatment works where it goes through various treatment processes.

2. How is water stored?

The use of reservoirs is useful to ensure that companies have reserves of water so if it hasn't rained over a prolonged period of time, there is still enough water to put through the treatment process. Storing the water in reservoirs also starts the cleaning process, as heavier particles settle to the bottom, meaning companies don't have to take them out during the treatment process.

3. What is screening?

Water companies put collected water through a screen to ensure any large objects, such as branches or leaves are removed. Objects such as these could cause disruption to the treatment process.

4. How are particles removed?

At some treatment works, companies add a solution to the water to make the particles bigger and easier to remove. This is called flocculation. To make sure they produce the purest water possible for customers, the water is then put through two more filters to remove tiny particles:

  • Rapid gravity filters which means the water is passed through a tank full of coarse sand. The sand traps particles as the water passes through.
  • Slow sand filters whereby the water is slowly filtered through large beds of much finer sand.

At some water treatment works companies also use additional methods, such as ozone, carbon and ion exchange, to remove microscopic and dissolved particles from the water.

5. How do companies ensure that tap water is at the highest standards?

Throughout the treatment process, water companies carry out multiple tests to ensure each step is working correctly. Once the water has been treated, the last thing water companies do is add a very small amount (less than one milligram per litre) of chlorine to it. This kills any remaining organisms or bacteria and keeps the water safe throughout the remainder of the system.

6. How does my water get to me?

Following final treatment, the water leaves the treatment works and is stored in covered reservoirs. It is then pumped to properties through a network of pipes and pumping stations. This distribution network is made up of 420,000km of mains - enough to go round the world 10 times!