Previous studies have highlighted the health benefits of coffee and tea, but they only focused on the comparisons between different consumptions. Consequently, the association estimate lacked a clear interpretation, as the substitution of beverages and distribution of doses were not explicitly prescribed. We focused on the “relative association” to ascertain the optimal consumption strategy (including total intake and optimal allocation strategy) for coffee, tea, and plain water associated with decreased mortality. Self-reported coffee, tea, and plain water intake were used from the UK Biobank. Within a compositional data analysis framework, multivariate Cox model was used to assess the relative associations after adjusting for a range of potential confounders. The lower mortality risk was observed with at least approximately 7 to 8 drinks per day of total consumption. When the total intake > 4 drinks per day, substituting plain water with coffee or tea was linked to reduced mortality, nevertheless the benefit was not seen for ≤ 4 drinks per day. Besides, a balanced consumption of coffee and tea (roughly a ratio of 2:3) associated with the lowest hazard ratios of 0.55 (95% CI: 0.47−0.64) for all-cause mortality, 0.59 (95% CI: 0.48−0.72) for cancer mortality, 0.69 (95% CI: 0.49−0.99) for cardiovascular disease mortality, 0.28 (95% CI: 0.15−0.52) for respiratory disease mortality, and 0.35 (95% CI: 0.15−0.82) for digestive disease mortality than other combinations. These results highlight the importance of the rational combination of coffee, tea, and plain water, with particular emphasis on ensuring adequate total intake, offering more comprehensive and explicit guidance for individuals.