The best way to save water is to use a mulch around trees and shrubs and in between garden rows. Use either organic materials or black plastic. First, make sure the soil gets a good soaking. If you must water, do so infrequently but deeply to encourage deep rooting and greater tolerance to dry spells. Water early in the day to reduce evaporation. Avoid overhead sprinkling since one third of the water evaporates before it has a chance to hit the ground. Avoid unnecessary hoeing and cultivation. Use bath or dishwater. Soaps, detergents, and ammonia are not generally harmful and may actually provide some nutrients. Add fresh water occasionally to wash out any heavy accumulation.