When the summer sun starts drying out your yard, it can be hard to know if you're watering too much or not enough. According to lawn care experts, many homeowners give their lawns more water than they need. For most lawns, the ideal watering time is about 25 to 30 minutes. According to the Environmental Protection Agency, smart watering systems can reduce outdoor water use by as much as 30 percent. Watering your lawn for the right amount of time can keep your grass healthy without wasting water.