There is an urgent need for reliable, cost-effective screening methods that can provide the environmental data necessary to support the EU Water Framework Directive (WFD) and its daughter directives such as the Ground Water Directive. Currently the method most commonly used in water monitoring is spot (bottle) sampling. This has a number of limitations; the most important being that it provides only a snapshot of the status of the body of water being sampled just at the instant of sampling. Spot sampling data can be misleading since levels of pollutants vary significantly with time because of fluctuating, often seasonal, inputs (e.g. domestic and industrial discharges, run off from land-fill sites, and agricultural land). In order to provide a more representative picture it would be necessary to take many spot samples over a period of time. High personnel and travel costs would make this a very expensive option. Other technologies have been developed to overcome the problems outlined above, and these include on-line continuous monitoring systems, sensors, toxicological assays, and passive sampling.

This paper will review the various methods that might be in a toolbox available to support the Water Framework Directive, and will discuss the potential contribution of passive sampling in this context.