District water supply networks treat and supply safe, potable water to the general populous. Water treatment facilities transform naturally sourced raw water into usable drinking and cooking water. Depending on the water source, the treatment process varies widely in the number of purification steps needed. Raw water sourced from rivers or lakes is first screened for large debris like driftwood and fish. It is then pumped through several sedimentation and filtration tanks to solids that are decreasing in size. Finally, water is disinfected and treated for taste before distribution. If water is sourced from the ground, only minimal filtration and disinfection may be needed. To ensure a lasting supply of potable water, many water supply networks employ storage reservoirs or water towers.
