Depending on the local climate and your particular landscaping, there may be enough rain to keep your lawn healthy without a sprinkler. According to the U.S. EPA, of the 26 billion gallons (98.4 billion liters) of water consumed daily in the United States alone, approximately 7.8 billion gallons (29.5 billion liters), or 30 percent, are devoted to outdoor uses. The majority of this is used for irrigation. And minimizing it would dramatically reduce water usage and costs.
Using less water on your lawn and garden allows more to stay in the ground or in a reservoir, which in turn helps maintain a natural H20 balance and saves some for future use. There are many parts of the country that do not have enough water to support the current population and levels of water usage. Even if you live in a place with ample rain, there may be a drought or even water restrictions. Severe droughts have hit countries across the globe from Pakistan to Russia to the United States to Kenya, so it's all the more critical to conserve--and it's amazing how every drop adds up!
If you have a large traditional turf lawn and extensive plantings (particularly ones that aren't adapted to the natural climate of your zone), this approach will be challenging unless you and your neighbors don't mind brown grass.
However, there are types of turf that are extremely drought tolerant. If the remainder of your landscaping is well adapted to the climate, it is feasible to avoid watering most if not all of the time. See what you can do. It adds up.
If you’re putting in new plants or turf, keep drought tolerance in mind.