Yes, the tap water in London is absolutely safe to drink. In fact, the UK’s drinking water is ranked joint-first in the Environmental Performance Index’s global water safety rankings, and the safety of the capital’s water is a big reason for that.
But what exactly is in London’s tap water, and where does it come from? Also, how is London’s tap water treated, and how does it compare to the tap water in other parts of the UK?
In this guide, we’ll answer all of these questions and more.
London Water Quality Report: What Is in the Water?
Municipal water in London consistently adheres to UK standards for safe drinking water. It doesn’t cause bacterial illnesses that are a problem in many other parts of the world, and locals and tourists can feel confident about drinking it.
London’s water system contains fewer contaminants than those in other major global cities. However, engineers note that lead pipes are still in use in parts of the city, particularly in buildings constructed before 1970, when the UK government outlawed this metal in plumbing.
People who own and live in older buildings should be aware of the possibility of contamination and take steps to replace the pipes with safer alternatives.
Environmentalists also draw attention to the presence of microplastics in the London municipal water supply. These poorly understood contaminants come from many consumer items and industrial sources.
Other substances in the water include chlorine derivatives to safeguard the public from dangerous bacteria. While not every resident or visitor enjoys the taste of chlorine in their drinking water, its presence in small amounts is safe, and there are only very small amounts of it present in London’s tap water.
In fact, according to a 2023 Thames Water Water Quality Report (Thames Water supplies most of Greater London’s drinking water) there were 0.58 milligrams of chlorine per liter in the water samples they tested. This is below the safety standard set by the World Health Organization (WHO) of 5 milligrams per liter.
As of summer 2024, London water suppliers have yet to add fluoride to the city’s drinking water. A nationwide push is underway in the UK to put a small amount of fluoride in tap water to protect children against tooth decay.
Is London’s Tap Water Hard or Soft?
London water is generally hard, though hardness varies significantly by location within the metropolitan area. Chalk and limestone are the most common underground materials that cause hard water in London.
Water filtered through limestone and other mineral deposits contains magnesium, calcium carbonates, sulfates, and bicarbonates.
Hard water is safe to drink, but some London residents and visitors do not like its taste and appearance. In extreme cases, hard water can cause visible white flakes of minerals in beverages and ice cubes.
It can clog coffee makers and cause buildup in electric kettles. Hard water can also cause dry skin when used for bathing.
Many residents use charcoal filter pitchers and other types of water softener systems to reduce the taste and properties of hard water and make it more pleasant to drink.
Where London Gets Its Water From
70% of London’s tap water comes from reservoirs upstream of the Thames River. Water also comes from the Thames and Lee Rivers and local underground sources in the water table.
The 320 water reservoirs serving London are located in suburban areas and underground. Local regulations protect these reservoirs from recreational uses like swimming, though fishing is allowed in many areas.
Several municipal water companies serve the London metropolitan area. Some of the larger companies include:
- Affinity Water
- Essex and Suffolk Water
- Sutton and East Surrey Water
- Thames Water
Affinity Water covers the outer parts of the London suburbs on the north, east, and west sides. Essex and Suffolk Water is responsible for the named counties.
Sutton and East Surrey Water serve the suburbs north of the city center. Thames Water is the largest water treatment company in the area, covering 76% of the London population in urban areas.
How Tap Water Is Treated in London
London treatment plants remove dangerous contaminants from groundwater and water reservoirs before distributing the water to homes and businesses. The city has 18 treatment plants run by the four regional water authorities.
Notable water treatment plants include the Thames Water Desalination Plant, which opened in 2010. It pulls salty water from the estuary and processes it into fresh water.
The plant also runs on renewable energy sources, which gives it an advantage in terms of costs and environmental impact.
Other London-area water treatment plants use chlorine and unique filtration methods to produce safe, clean water. For example, the Walton Water Treatment Works uses a combination of ozonation, sand filtration, activated carbon filtration, the addition of chlorine, and other methods to produce clean water.
Wastewater is processed by separate treatment plants in the London metro area, removing as much chemical and bacterial contamination as possible before allowing the water to return to the rivers and eventually to the ocean.
Does London Have the Cleanest Tap Water?
All of the UK’s tap water is very clean, and there are no safety issues associated with drinking municipal water in any region. The UK’s water quality is consistent across the country, so it’s not accurate to say that the water in one area is cleaner than in others.
However, while the water in London is clean, residents and visitors often prefer the taste of tap water in regions such as Scotland, as it has fewer minerals and contaminants.
Final Thoughts
While London’s public tap water is clean, safe, and well-regarded, many people dislike its taste because it’s hard. Personal or home filtration may be necessary to produce water that is on par with bottled water in terms of taste.
If you choose to drink London tap water, there are no risks to your health. As London improves its water filtration systems, its rankings will continue to rise compared to Europe and the rest of the world.
World travelers and residents should feel confident they can drink tap water in London without it negatively affecting their health.
