Water Journal : Water Journal December 2011
microbiology refereed paper 82 DECEMBER 2011 water technical features Abstract This paper provides a synopsis of a 'User's guide to microbiological program design and collection of exposure data', one component of a National Water Commission (NWC) fellowship project completed in 2011. While the guide was written to assist in optimising the collection of microbial (pathogen) exposure data, the schema outlined can be adopted more broadly to other types of monitoring. Step-by-step guidance on the planning and design of a water quality monitoring program, including how negotiations with water- testing laboratories may be approached and questions that should be asked by those commissioning testing, is presented in this paper. Effective communication between those commissioning water quality testing and laboratory personnel is a key element in deciding the most appropriate method to be employed for monitoring and, also, in determining how methodological shortfalls and other data gaps might be best addressed through targeted research. The 'User's guide to microbiological program design and collection of exposure data' provides an aid to enhance communication. Introduction In modelling health risks there are major sources of risk assessment uncertainty that are difficult to estimate directly due to limitations of available data and monitoring procedures. Important data gaps include the prevalence and concentration of pathogens in various water sources. To address such data gaps, monitoring programs must be designed to ensure not only best value for money, but also, fitness for purpose. Design of a water quality monitoring program requires decision-making about many aspects, including: the most suitable micro-organism(s); the method to be employed for testing; the number of samples to be tested; and the monitoring frequency. Such decisions are dependent on the availability, suitability, accuracy and reliability of analytical or instrumental methods; the cost of such methods; regulatory requirements; and the purpose for which monitoring is being undertaken. The steps in planning and designing a microbiological monitoring program, excluding sampling issues, are shown in Figure 1. Of note are the interdependency of multiple steps and the central importance of first carefully defining the purpose for which monitoring is intended (Step 1). In defining the specific question to be answered, decision-making about the micro-organism to select for testing (Step 5), the method to be employed (Step 6) and the minimum number of samples required (Step 7) is simplified. Another important step in planning and designing a water quality monitoring program is to consider whether there are existing data that can be used (Step 2) as a substitute for, or as a supplement to, data that are planned to be collected. Where data are available but scrutiny J O'Toole A user's guide to monitoring program design and collection of exposure data MONITORING MICROBIOLOGY WISELY Step 1: Define purpose of monitoring Step 2: Are data available and useful? Steps3&4: Select laboratory and engage with personnel with necessary expertise If no data are available and/or suitable, new data will have to be collected Data are available and fit for purpose Step 5: Obtain information about micro- organism best 'fit for purpose' Step 6: Select method based on the attributes of available methods Use data to supplement data that are to be collected Use data as a substitute for data that you had planned to collect Step 7: Determine the number of samples Step 8: Document method operating characteristics and assumptions with collected data Figure 1. Steps in designing a water quality monitoring program.
Water Journal April 2012
Water Journal November 2011