National Groundwater Awareness Week is March 6–12, making it the perfect time to talk about groundwater in Nebraska! What exactly is groundwater? It is the water below the earth’s surface that fills the interconnected voids and cracks in and around soil particles, sand, gravel and rock. Groundwater is the most abundant supply of freshwater in the world and is the water source that private drinking water, irrigation, livestock and many public water supply wells draw from.