To provide updated estimates of drinking water intake (total, tap, plain bottled) for groups aged ≥1 year in the USA and to determine whether intakes collected in 2005–2006 using the Automated Multiple-Pass Method for the 24 h recall differ from intakes collected in 2003–2004 via post-recall food-frequency type questions.

Cross-sectional, observational study.

What We Eat in America (WWEIA), the dietary intake component of the US National Health and Nutrition Examination Survey (NHANES).

Individuals aged ≥1 year in 2003–2004 (n 8249) and 2005–2006 (n 8437) with one complete 24 h recall.

The estimate for the percentage of individuals who reported total drinking water in 2005–2006 was significantly (P < 0·0000) smaller (76·9 %) than that for 2003–2004 (87·1 %), attributable to a lower percentage reporting tap water (54·1 % in 2005–2006 v. 67·0 % in 2003–2004; P = 0·0001). Estimates of mean tap water intake differed between the survey cycles for men aged ≥71 years.

Survey variables must be examined before combining or comparing data from multiple WWEIA/NHANES release cycles. For at least some age/gender groups, drinking water intake data from NHANES cycles prior to 2005–2006 should not be considered comparable to more recent data.