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Best Tap Water Quality in the UK – Study


15 February 2021

Ever wondered what’s in your water? Or how your water differs from others? We’ve taken a look into the water quality of counties across England and parts of Wales, specifically, the most hazardous elements and which parts of the nation have higher levels than others.

Using government and water company data, we’ve taken a look into 5 of the leading heavy metals and impurities that we drink, eat, bathe in, and clean with from our taps.

Key Takeaways:

  • South London and the surrounds of East Surrey and West Kent have the highest average rate of impurities and elements in their water
  • Flintshire and Denbighshire have the lowest average readings of impurities and elements in their water
  • South London’s tap water quality has the highest readings of lead of any part of England and Wales
  • People in Luton, Thames Valley and North Wiltshire are exposed to the most nitrates in their water
  • Traces of aluminium in water are highest in the South West of England, with Dorset, Somerset and Wiltshire recording the highest levels
  • Turbidity (cloudiness) of water in the UK is incredibly low, however, Hertfordshire have the highest turbidity in water quality tests
  • Almost half of England and Wales has hard or very hard water, with the majority of hard water counties towards the East Anglia and the South East


What’s In The Water Where You Are?

In the charts below, you can see how your county scores for its levels of nitrates, aluminium, and lead in the water; as well as the turbidity, and water hardness, which are often associated with the quality and taste.

Chart depicting the UKs water quality test reading for England and parts of Wales

Which counties have the highest levels of lead in water quality tests?

Lead is rarely found in water at source (natural springs etc), however, amounts of the dangerous metal can be often be found in areas that still use or have concentrations of lead piping and connectors in their system; both at the main and within people’s own houses.

The UK counties with the highest levels of lead in water quality tests?

Our research found South London and West Sussex to have the highest concentrations of lead, followed by much of the North West.

South London’s water quality was found to have the highest levels of lead in England, with 2.6 micrograms of lead per litre (ug/l). Though well below the 10 micrograms (ug/l) legal limit, South London’s results are far higher than the 1.6 micrograms (ug/l) average found in West Sussex, the second highest result in the tests analysed.

At the other end of the scale, Northumberland, Tyne and Wear, and Durham were found to have the lowest levels of lead in England, with just 0.03 micrograms of lead per litre (ug/l).

If you are concerned about whether you have lead pipes please view a guide to checking your pipes for lead.

Counties with the highest levels of nitrates in water quality samples?

A natural compound of nitrogen and oxygen, nitrates are often found in foodstuffs and are part of normal diets. They’re presence due to their use in intensive farming efforts, as part of natural and manufactured fertilisers. However, these nitrates often percolate into groundwater systems or ‘run-off’ into rivers and other water sources, which we then use to drink or bathe in.

Linked to various health issues, nitrates high levels of nitrates can pose problems for children under 6 months old, leading to conditions such as blue baby syndrome and health defects in later life.

Counties in the UK with the highest levels of nitrates in water test samples

All the counties analysed were below the legal limit of 50 parts per million (50 mg/l) of nitrates in water tests. However, our research did find some counties to have as much 32.1 mg/l in their water tests. These areas being Luton, Thames Valley and North Wiltshire.

At the other end of the scale, much of the North West, including Cumbria, Greater Manchester, Lancashire, and Merseyside, were found to have the lowest nitrate level in England and parts of Wales, at just 1.94 mg/l.

Which counties have the highest levels of aluminium in their water?

Aluminium salts are used by water companies and authorities to help purify and treat water. The salts aiding in the removal of potentially harmful particles, including bacteria and other microorganisms that could cause health issues.

To avoid discolouration and impacting taste, the UK government has set an aluminium ceiling of 200 parts per billion (ug/l). Under these current levels, aluminium is not officially linked to any health concerns. However, some tentative reports have suggested links between Alzheimers and high levels of aluminium in tap and drinking water.

Counties that have the highest levels of aluminium in their tap water

As our chart show’s, the highest figures of aluminium in the tests analysed are well below the legal limits.

That said, Dorset, Somerset and Wiltshire were found to have the highest levels of aluminium in their water. The three South West counties each recording 63 ug/l of aluminium reported in their test results. At the other end of the results, Berkshire and Hertfordshire tests were found to have just 5 ug/l of aluminium.

Note: Current studies concerning the link of aluminium in water and Alzheimers are yet to be dismissed or confirmed. For more information please visit here.

Which counties have the highest levels of turbidity in water samples?

Turbidity relates to clarity of liquid, highlighting the cloudiness and an opaqueness often caused by particulates present in the water.

Not only is high turbidity aesthetically unappealing, it can also pose a health concern as well. This is due to the turbidity causing particulates providing food and shelter for pathogens in the water.

Map showing which UK counties highest levels of turbidity in  water samples

Legally, domestic drinking water in the UK is not allowed to have a turbidity level of over 4 Nephelometric Turbidity Units (NTU). Our research of water quality test results found Hertfordshire to have the highest turbidity score, at 0.33 NTU. Far below the legal NTU limit.

Staffordshire, Warwickshire, and the West Midlands are the counties with the lowest turbidity scores, with just 0.01 NTU.

Which counties have the hardest and softest water England and Wales?

Calcium and Magnesium are the main components of hard water and though not a health risk, can be a nuisance. This is because of mineral buildup in, on and around fixtures, as well as poor soap and detergent performance.

Map showing which UK counties have the hardest and softest water?

Our research found that 11 of the counties’ data we analysed had ‘very hard water’, with 15 described as hard. The vast majority of these hard water regions being found towards East Anglia and the East Midlands.

Whilst the East of England has a high concentration of hard water areas, the West is far softer. The North West and South Western regions see the softest water in England and part of Wales.

Which areas have the most impurities in their water?

When we analysed water quality data against legal limits, we found South London and the surrounding East Surrey and West Kent to have the highest average rate of impurities and elements against legal limits. 

According to our analysis, water in the three areas has an average rate of impurities and elements of 21.8%. Meaning, that readings of impurities and elements were on average 21.8% of legal limits.

Conversely, our analysis of UK water quality readings found Flintshire and Denbighshire to have the lowest average rate of impurities and elements against legal limits (4.55%), followed by Shropshire and Powys (5.5%). 

The UK’s Water Quality

Overall, our research shows how water companies in the UK have managed to keep our tap water within safe limits. This is despite the various geographical challenges and man-made consequences, that could have detrimental impacts on our health, appearance or even the very utensils we use, if they weren’t dealt with.

Lee Devlin, Founder, at Homecure Plumbers comments:

“Ensuring water is safe, treated and clean of potential contaminants is no easy feat, with many variables based on geography, land usage and even the actions and infrastructure of our ancestors having an impact on how our water reaches us today.”

“Our research highlights just how different the water compositions across much of England and parts of Wales are, with one of the biggest surprises being the relatively high (although safe) levels of lead in South London and West Sussex.”


Measurements were taken from the most recent 2020 water quality reports from each water authority. Where counties and water authorities cross over, an average (central postcode) is used to provide an estimation for that county.

Measurements have been selected across a wide range of microbiological, metal, mineral and other measurements that are considered important to water quality, including water hardness.

The percentage of impurities and element was calculated by working out a percentage of readings against legal limits for each element and averaging the scores together to provide and overall average percentage.

Data Sources:

  • Water quality postcode search (

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