Tap water consumption amongst a cohort of UK twins is linked to perceptions of taste and health benefits

Drinking sufficient clean water is essential for human health. Surveys that estimate daily water intake report striking differences between individuals and countries, but the factors determining such variance remain unclear. Here we report results from the first survey that, to our knowledge, evaluates concurrently how sociodemographic characteristics, public perceptions of taste and health benefits and genetic factors influence tap water consumption within the home. We administered the survey amongst nearly 3,000 adult twins living in the UK (members of the TwinsUK cohort). Respondents consumed 2.40 ± 1.14 L/day of water from their household taps through drinking and cooking. This rate is at the high end of published values and means that 39–65% (female) and 8–39% (male) of TwinsUK participants meet international recommendations on daily intake. We also found that variability in tap water consumption is moderately explained by genetic factors (heritability (h 2 ) = 19 – 31%, p < 0.0001), but environmental and stochastic factors explain more of the variance. Indeed, respondents who like the taste of their tap water or consider it to have positive health benefits consume significantly more (~0.5 L/day; p < 0.001) than individuals with negative perceptions. Rank-based and intersectional analysis (I-MAIHDA) revealed that respondents who are female and/or over the age of 45 recorded the highest intake, on average, although these demographic groups represent a higher percentage of surveyed respondents than the UK population. Focusing on older adults fills a common research gap in drinking water research, but we acknowledge our findings need to be reassessed amongst a representative population cohort before stronger inferences can be drawn around public perceptions, consumption patterns and health outcomes. Nevertheless, our study suggests there are opportunities to increase overall levels of consumption to benefit public health through improving tap water taste and increasing knowledge of health benefits.