TwinsUK research reveals how tap water habits, perceptions and chemistry shape health

13th January 2026 – by Aaruthy Suthahar

New research using data from TwinsUK has provided valuable insights into how our perceptions, behaviours and even genetics influence how much tap water we drink, and what that might mean for our health. 

In two complementary studies led by researchers at TwinsUK and King’s College London in collaboration with hydrogeologists scientists explored both how much tap water people consume and whether variations in water chemistry across the UK are linked to health outcomes. 

The first study, soon to be published in PLOS Water, focused on the factors that drive how much tap water people actually drink. Surveying almost 3,000 TwinsUK participants, the team found that those who liked the taste of their tap water or believed it had health benefits drank around half a litre more per day than those with negative perceptions. They also discovered that water consumption is moderately heritable, meaning that genetics play a role alongside lifestyle and environment. 

The second study, published in Science of the Total Environment, combined drinking water data from nearly 2,000 UK twins with local water quality information to create personalised estimates of exposure to minerals and solutes such as hardness, nitrate, chlorine and selenium. By linking these data with detailed questionnaire responses on drinking habits, the researchers were able to more accurately assess individual differences in water intake and potential health effects. 

They found limited evidence that tap water composition is associated with health outcomes, with only small or inconsistent signals across models. Importantly, these findings were interpreted as a positive public health message, suggesting that UK tap water is a safe and reliable source of hydration for most people. 

Dr Ruth Bowyer, who led the research, said: 

“By combining large-scale cohort data with detailed information on both water chemistry and personal behaviour, we were able to see that people’s drinking habits are shaped by a mix of perception, genetics and environment. It’s also reassuring that we found little evidence of negative health effects, which highlights the safety and quality of UK tap water, although more research is needed looking at more detailed measures of health.” 

Together, these studies demonstrate how personal behaviour, perception and environmental exposure interact to influence everyday health, and how large population studies like TwinsUK can help refine methods for assessing these links more accurately.