Health Effects of Rainwater Consumption

Investigators
K Leder
M Sinclair
A Forbes
D Cunliffe
S Rodrigo

Funded by: NHMRC and CRC for Water Quality and Treatment

This project used methodology previously developed for a study of tap water in Melbourne to determine whether microorganisms in untreated rainwater contributed to gastroenteritis in consumers of the water. The study was carried out in Adelaide where more than 12% of households use rainwater as their usual source of drinking water. 300 households who already drink untreated rainwater were recruited and randomly allocated to receive either a real or sham water treatment unit for treating rainwater. The real units removed microorganisms from water while the sham units did not. Neither the households nor the researchers knew which type of unit had been allocated (double blind design). The health of household members was followed for 12 months, then rates of gastroenteritis in the two groups were compared to determine whether removal of microorganisms from water was associated with a detectable change in illness rates.

The results showed that rates of gastroenteritis were very similar in the two groups.  People who drank untreated rainwater displayed no measurable increase in illness compared to those who drank filtered rainwater.

References:

Drinking rainwater: a double-blinded, randomised controlled study of water treatment filters and gastroenteritis incidence
Rodrigo, S., Sinclair, M., Forbes, A., Cunliffe, D. and Leder, K. (2011) American Journal of Public Health, 101(5); 842-847.

Effectiveness and cost of recruitment strategies for a community-based randomised controlled trial among rainwater drinkers.
Rodrigo, S., Sinclair, M., Cunliffe, D. and Leder, K. (2009) BMC Medical Research Methodology, 9(51);