Water Quality

Assessing the Microbial Health Risks of Potable Water

Greg Simmons, Jane Heyworth
Auckland Healthcare
Private Bag 92 605 Symonds St
Auckland, New Zealand
E-mail: gregs@ahsl.co.nz

 

Abstract

The health risks associated with tank rainwater consumption are not well defined. This paper provides a schematic model for considering the health impacts of rainwater with microbial contamination using the epidemiological approach but encompassing risk assessment as a central theme. The issues that need to be addressed in a microbial risk assessment (MRA) are identified. These include, for example, the numbers of pathogens in tank rainwater, their ability to survive and multiply; the extent of individual exposure; and the measurement of health outcomes. The merits of the various epidemiological study designs as tools to estimate the risk of illness from rainwater exposure are discussed. The MRA framework enables a systematic estimation of health risk as a consequence of potable tank rainwater contamination and has important implications for the setting of microbial standards for potable rainwater.