Groundwater is essential for people and ecosystems world-wide, especially in low income countries where large water utilities that use surface water are less common. Good information can support better use and management of this essential resource. Many reports, guides, databases, text-books, maps, learning aids and other material with information on groundwater are available on-line for free; the challenge is to know where to find them. This Practices, Research and Operations in Water, Sanitation and Hygiene (PRO-WASH) curated guide provides a list of some of the organizations and websites that make these knowledge resources available. The guide is focused on Sub-Saharan Africa, but is also relevant to groundwater elsewhere.