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 the first survey to concurrently evaluate how perceptions of taste and health benefits and genetic heritability influence tap water intake within the home. We administered the survey amongst nearly 3000 adult twins living in the UK (members of the TwinsUK cohort) and found that 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. Twin model analysis indicates that tap water consumption is moderately heritable (h2 = 19 – 31%, p < 0.0001), meaning daily intake is partially influenced by genetic factors but environmental and stochastic factors have greater effects. We calculate that respondents consume 2.38 ± 1.16 L/day of water from their household taps through drinking and cooking. This rate is at the high end of published values, and implies that the majority of TwinsUK participants meet recommended international guidelines, although there is substantial heterogeneity. Respondents who are female, in older age groups or report their ethnicity as white recorded highest intake, on average. Our study demonstrates that drinking water research should document intake, perceptions and genetics in tandem to better understand population tap water consumption patterns and identify opportunities to increase consumption for public health benefit.