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uk water treatment

How Is Water Treated In The UK and Can Water Recycling Help?

How Is Water Treated In The UK?

uk water treatment

As much as us Brits complain about the amount of rain we get, without it, we wouldn’t be able to supply the 16.6 billion litres of water to the nearly 70 million people that live here with clean drinking quality water.

The 416,175 km of water mains delivers some of the highest quality water on the planet to 98% of urban and rural households.

Water is a highly valuable resource, particularly in such an unpredictable climate. But it can contain lots of different contaminants like lead and even microplastics. This is why treatment is so important, particularly now when pollution is at an all-time high. Here is how our water is treated in the UK and how grey water recycling and rainwater harvesting can help.

Water treatment process steps

Rain collection

Pure water falls as rain which runs into rivers or lakes, or soaks into the ground and forms ‘groundwater’. Your water provider pumps this water out and takes it to the treatment site where it is stored. The amount of water that can be taken is restricted, as taking too much water from one place can damage the ecosystem that it’s part of. This is why conserving water is vital and why we all have a role to play.

Rainwater Storage

It is important to be able to store as much water as possible in case we have periods of very little or no rain. We must safeguard our supply so that in these drier periods, we still have a supply to keep day-to-day life running normally, for as long as the dry spell lasts. The rainwater that is stored has likely come from different sources, so there is a slightly different process for each source. However, the rest of the process is standard.

Storing the water also begins a natural cleaning process, as naturally heavier particles sink to the bottom and can be easily filtered out.

Rainwater Screening

Rainwater screening is the removal of large contaminants from the water. This generally includes leaves, branches and even litter. It will remove anything that could block or clog the rest of the treatment process.

Removing particles

There are two main components to removing particles: Flocculation and filtering.


Flocculation is the name of the process by which a solution is added to the water to make the small particles bigger and easier to remove.


Filtering is done to remove the invisible particles. The first filter is a Rapid Gravity Filter (RGF). This involves the water being passed through a large tank full of very coarse sand which traps these invisible particles as the water passes through. The second filter is a Slow Sand Filter which is a large bed of very fine sand. This traps even smaller particles that have passed through the RGF. This is the last part of the process before the final treatment.

Final treatment

Once all the particles are removed, even the ones too small to see, we can add the final treatment to make it safe to drink. The final treatment is chlorine, which acts as a disinfectant, killing any remaining bacteria and sterilising the water. It keeps the water clean all the way through from the treatment site to your tap. And don’t worry, it’s a tiny amount, less than one milligram per litre of water. Other ways of sterilisation include adding ozone (oxygen) and using an Ultraviolet light.

Getting it to you

Once the water is treated and ready to go, it makes its way to you through the mains water supply and out your tap.

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How does this compare to water recycling?

A rapidly increasing population, combined with an unpredictable climate is putting pressure on local water supplies which may cause interruptions to local mains water supplies in the near future. Without interventions and innovations, water demand in England and Wales is forecast to rise from 16.6 billion litres of water per day to 24.8 billion by 2050.

Harvesting your own rainwater or recycling grey water are both fantastic environmentally friendly options that allow you to reduce the impact your household has on local water suppliers.

You can think of our water recycling systems as small-scale water treatment sites. You can harvest your own rainwater, store it, treat it and then use it for irrigation, laundry, vehicle washing or flushing your toilets. Or you can recycle grey water which is collected from baths, showers and hand-wash sinks and is used for toilet flushing. By doing this, you are not only reducing your mains demand, but the amount of water that is going into the sewer system too. The only difference is the water you use is not to a potable (drinking) standard.

Another hugely important aspect of water recycling is the ability to attenuate storm water. If you live in an area that is particularly prone to flooding, you might want to consider using a rainwater harvesting system.

The UK has a wealth of skills, techniques, and resources to reduce the impact of human and environmental harm from floods. We are considered a world leader in flood management and defence as for every £1 spent on flood protection in the UK saves £8 in repairs. But as many people will know, sometimes this is not enough.

We sometimes take our access to clean, safe water for granted. But it’s important to remember that currently, between 1.1 and 1.8 billion people globally lack access to safe water. And by 2025, 66% of the world’s inhabitants could live in water-stressed conditions.

We should all be taking action to conserve water so if you want to do your part and want more information on how Aquaco can help you take action, please get in touch with a member of the team.

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