Groundwater is a vital natural resource, being increasingly under pressure of climate change and human activities. We need to monitor the invisible groundwater in order to use and protect it properly. Therefore, IGRAC has published 'National groundwater monitoring programmes: A global overview of quantitative groundwater monitoring networks'. This document provides an overview of quantitative groundwater monitoring networks at national scale. It is prepared to encourage sharing of monitoring experience, assist in improvement of monitoring and data processing and increase awareness of a general lack of groundwater monitoring. The full report, as well as four regional overviews and all 81 country profiles, is now available for download.