All forms of irrigation need a push or pressure to move water from its source to its destination. Water sources include wells, springs, lakes, creeks, canals, rivers, cisterns, elevated tanks, or municipal water supplies. The amount of pressure or push required depends on many things including the height water must be lifted, length and size of the delivery pipe(s), crop and size of the area to be irrigated, and the distance water needs to be moved from the source to the field, greenhouse, or tunnel.