Background
Waterpipe smoking is growing worldwide, but little is known of its epidemiology in the UK due to its absence from national health surveys. We sought to address this by calculating the prevalence of waterpipe smoking among secondary school students in southeast London.

Methods
We conducted a pooled secondary analysis of routine health surveillance surveys among 11–17 year olds in convenience-sampled secondary schools from three ethnically-diverse areas of southeast London. We calculated ever (lifetime) waterpipe use, and compared its sociodemographic correlates to ever (lifetime) cigarette use. In one area we collected data on patterns of waterpipe use.

Results
Of 2,098 respondents (mean age 14.1 ± 1.7 years, 55.7 % male, 46.6 % of black ethnicity), ever waterpipe use was 39.6 % (95 % CI 37.6–41.7 %) and was higher than that for ever cigarette use (32.4 %; 95 % CI 30.5–34.4). While waterpipe users were significantly and independently more likely to be male and of non-white ethnicities, at least 30 % of all age, gender and ethnic sub-groups had tried waterpipe smoking. In contrast, cigarette users were more likely to be older and of white ethnicity. In one of the three areas, over a quarter of waterpipe users were occasional or regular waterpipe smokers, and most were introduced to and currently used waterpipe in waterpipe-serving premises or friends’ homes.

Conclusions
Waterpipe smoking prevalence was high in southeast London, and users exhibited a different sociodemographic profile to cigarette users. Waterpipe should be included in national health surveys of young people. National surveillance is warranted to help develop suitable interventions to prevent uptake and promote cessation.