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