One hundred and thirty two under Five Children (U-5C) with Diarrhoea (cases) and age-matched U-5C without Diarrhoea (controls) were randomly selected from Oni-memorial Children Hospital and University College Hospital in Ibadan. A 10-item observational checklist was used to assess the sanitary status of the drinking water sources and household storage containers of consenting households within 24-48 hours of recruitment. Total Coliform Bacteria (TCB) and Escherichia coli
in paired drinking water samples were determined using APHA standard procedures. The results were compared with World Health Organization (WHO) guidelines for drinking water quality. Data were analysed using descriptive statistics, t-test, Chi-square and spearman-rank correlation test. The median TCB count for source and household stored drinking water samples for cases (20 and 22/100ml) exceeded the WHO guideline. Escherichia coli
was absent in water samples from source among cases and controls, while 25% and 5% of cases and controls respectively had Escherichia coli
in their stored drinking water. Deterioration of stored drinking water quality may be as a result of poor water handling within homes. Results of sanitary inspection show that mean risk scores among cases and controls were 5.4 ± 2.2 and 3.2 ± 1.9 (p<0.05) for drinking water sources and 2.4 ± 1.8 and 1.2 ± 0.7 (p<0.05) for household storage containers. The results show a significant association between quality of source and stored water and diarrhoeal disease incidence among U-5C (OR=0.076, p<0.05). This study therefore recommends training of mothers of children under five years on strategies for improved household water treatment, safe storage, handling and hygiene conditions within households in order to improve water quality.