Effect Based Monitoring in Water Safety Planning - Sampling strategies and sample pre-treatment options and decision-making tool for selection of sampling methods

“In vitro bioassays are sensitive screening tools to detect complex mixtures of micropollutants in water samples, but micropollutants are often present at low concentrations, particularly in drinking water and clean source water. Therefore, there is a need to enrich samples prior to bioanalysis. This report summarizes commonly applied sampling strategies and sample preparation options and proposes a decision-making tool to assist users to select appropriate sampling methods.
The sampling strategy will depend of the purpose and objective of the sampling campaign, as well as the sample context. For example, if the purpose of a sampling campaign is to assess the product quality of a drinking water treatment plant, with the objective of comparing the effect in the treated product water to an effect-based trigger value, then only the product water needs to be collected. If we want to understand critical processes, it might be required to sample at different stages of a treatment chain. The type and volume required will depend on the sample, with composite sampling and smaller volumes recommended for wastewater influent and effluent. In contrast, grab sampling and larger sample volumes are more suitable for drinking water and recycled water.
Once a water sample has been collected, a number of decisions regarding sample pre-treatment need to be made. For example, samples should be processed within 48 hours of collection, while samples containing chlorine should be quenched immediately after collection. While many studies filter samples prior to enrichment, the type of filter and the filter pore size used varies widely in the literature. We recommend filtering water samples with a turbidity of 5 nephelometric turbidity units (NTU) or greater using glass fibre filters with a pore size between 0.7 to 1.5 µm.”

(Citation: Neale, P., Leusch, F., Escher, B. – Effect Based Monitoring in Water Safety Planning – Sampling strategies and sample pre-treatment options and decision-making tool for selection of sampling methods – GWRC EBM in WSP – WP3.3 (2020))