Groundwater recharge estimates are required for the management of river basin districts under the new Water Framework Directive. Different recharge estimation techniques are described in this paper according to the following categories: inflow estimation, aquifer response analysis, outflow estimation and catchment water balance. Examples of their application in Ireland are provided. All estimates involve a significant degree of uncertainty, and it is therefore essential to employ more than one method. The choice of methods will depend on the conceptualisation of the flow system and the specific objective of the study.