Environmental and human health impact assessment is an essential instrument to adequately evaluate hazards and associated risks. The approach is based on guideline documents on water recycling released by Australian authorities (NRMMC-EPHC-NHMRC 2009). The Australian guidelines for water re-use by MAR have been applied at two sites (Berlin-Tegel and Castellon). Australian guidelines provide ready-to-use and user-friendly instructions and checklists based on a step wise approach with a strong focus on implementation.

Within the first study these guidelines were applied to the MAR site at Berlin-Tegel in order to demonstrate an additional methodological approach for impact assessment of MAR sites. Although Berlin-Tegel is an already running MAR project a periodic reassessment should be part of any proactive quality assurance. The proposed models for water flow and substance transport allow a first tier estimation of present concentrations in ambient groundwater and the impacted zone in the aquifer. The use of stochastic models is not mandatory within the guidelines. A criticism which can be identified related to the use of solely deterministic models, is that especially in early stage risk assessments, where uncertainties are usually high, deterministic models tend to pretend a level of certainty which often does not represent reality.

The second study focuses on a well injection site currently in pilot phase at Castellon (Spain). Here, the Australian guidelines for risk assessment have been applied in two steps: entry level assessment and maximal risk assessment.