Objectives: The present study aims to estimate the incidence of preventable infectious diseases or associated symptoms among young children in Bangladesh and also determine the factors affecting these conditions. The study hypothesised that various background characteristics of children as well as their parents influence the incidence of morbidity of children aged below 5 years. Setting: The study used data from the most recent nationally representative cross-sectional Bangladesh Demographic and Health Survey (BDHS) conducted in 2011. Participants: A total of 7550 children aged below 5 years during the survey from mothers aged between 12 and 49 years are the participants of the study. Results: In general, younger children were more likely to suffer from multiple health conditions than their older counterparts. Children belonging to households classified as poor (OR=1.425, 95% CI (1.130 to 1.796)) or middle (OR=1.349, 95% CI (1.113 to 1.636)) faced greater risk of illness than those from well-off households. A combination of source and treatment practices of drinking water showed a significant impact on incidence of childhood morbidity. Children from households using untreated non-piped water were 85.8% (OR=1.860, 95% CI (1.269 to 2.728)) more likely to suffer from comorbidity than those who treat their piped drinking water. However, we observed that water treatment alone has no impact unless the water itself was sourced from a pipe. Conclusions: Accelerated programmes promoting access to safe drinking water along with water treatment practices, and better household environment may prove effective in reducing the incidence of childhood morbidity in Bangladesh.