While water resources vary over time (as from drought, or, an abundant snowpack, for example), sustainable use of water requires a reserve that can be maintained and managed so as to ensure the supply for future generations. Sustainable activities do not reduce options or otherwise impoverish future generations.

One way to make a significant impact on your use of water to irrigate your garden and lawns is to install a programmed, automatic irrigation system. These systems can save you time and money and just as important, they help conserve water.

Choose a system that can be reprogrammed easily to adjust to changing seasonal requirements.

Most systems use a system of underground pipes, sprinklers, and emitters to water specific areas of a garden or turf, and divide the property into specific areas so that plants with similar root depths and watering needs can be watered by the same irrigation valve and cycle. An irrigation controller includes a timer that activates the valves for each watering zone. The timer allows you to water at the most efficient time of the day - usually the very early morning hours - when evaporation losses are minimal.

Systems provide two categories of irrigation: overhead and low volume/drip.

Overhead systems use sprinkler heads to spray water over an area. In arid and semi-arid areas, these are recommended primarily for turf irrigation. Overhead systems may use up to five gallons of water per minute, and apply up to 1½ inches of water per hour. System efficiency is dependent on water pressure and availability, as well as environmental factors such as watering when winds are minimal, and on maintenance factors, such as seeing that sprinkler heads are correctly aligned and unclogged.

Drip irrigation emits a slow and steady application of water at the roots of plants and shrubs, directly where it is needed rather than through the air where it evaporates. The rate of flow is determined by the size of the aperture of the emitter and by the number of emitters programmed on a single valve or cycle. Care should be taken to not overload the system and exceed the household's water pressure capacity. It is generally preferable to program several areas with separate watering cycles than try to water a large area on a single cycle.