Can tap water raise blood pressure?

According to the World Health Organization, as many as one in three people over the age of 30 struggle with hypertension. Scientists say that, besides a salty diet and an unhealthy lifestyle, a high concentration of sodium in drinking water may also increase the risk of developing the condition. Where is the situation the most serious?

Salt, water and hypertension

An international team of scientists led by Rajat Das Gupta from Vanderbilt University Medical Center analyzed data collected from studies conducted in countries across North America, Asia, Europe, Africa and Australia up to 2025. The researchers found a link between the prevalence of hypertension and the chemical composition of drinking water in particular regions.

It turned out that in areas where tap water contains more sodium, residents have systolic blood pressure higher by an average of 3.22 mm Hg and diastolic blood pressure higher by 2.82 mm Hg. Salinity in drinking water also translates into a 26 percent increase in the risk of developing hypertension.

Which European countries have overly salty tap water?

The maximum permissible sodium concentration in drinking water established by the World Health Organization and accepted throughout Europe is 200 mg/l. In reality, in most countries on the continent, the value is much lower and does not exceed 20 mg/l.

A synthetic review prepared on the basis of public health documentation and national and regional reports on drinking water salinity shows that concentrations above 30 mg/l are observed in coastal areas of the Netherlands and in British locations with more mineralized, harder water. The problem is most noticeable in areas located within 10 km of the coastline and in towns using natural mineral water sources, such as Oligocene water drawn from deep aquifers.

The highest risk of excessive sodium consumption is observed in dry coastal areas of Spain, on the Greek islands, and above all in Malta and Cyprus, where a significant portion of drinking water is produced through desalination. If tap water contains 150 mg/l of sodium and someone drinks 2–3 liters of it per day, they may develop hypertension over time, according to Rajiv Chowdhury from Florida International University.

Water salinity will become an increasingly serious problem

More than half of the world’s drinking water resources come from underground sources, including groundwater, which is particularly vulnerable to changes in mineral composition. These changes are influenced by factors such as heavy rainfall and surface water occurring in a given area. Unfortunately, climate change is increasing the risk of salinization of aquifers as sea levels continue to rise.

This threat particularly affects coastal areas with relatively flat terrain. Seawater will increasingly penetrate larger inland areas, bringing with it sodium that is harmful to the heart. Intense storms, also associated with climate change, intensify this negative phenomenon, leading to increasing soil salinity and, consequently, greater salinity in groundwater as well.

How can people protect themselves from sodium in drinking water? Researchers suggest that regular monitoring of tap water quality and softening technologies such as reverse osmosis and distillation will become increasingly important.

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While writing the article, I used:

Gupta RD, Kunutsor SK, Lopez-Salamanca DE, Mercy FT, Nawal N, Tejada CE, et al. Association of drinking water salinity with elevated blood pressure and risk of hypertension among coastal and other populations: a systematic review and meta-analysis of observational studies. BMJ Global Health. 2025;10:e018543. https://doi.org/10.1136/bmjgh-2024-018543