Well most irrigation systems use alot less water than traditional watering techniques. So as far as saving money it just depends on how much you already use vs. how much the new irrigation system would use. In my experience the water usage is cut just about in half when compared to traditional watering techniques. A quality irrigation control system is key as well.
I completely agree with the answer from Gabe’s Plumbing. Having a site-specific irrigation system installed will cut your water bill down significantly. Some studies indicate by as much as half. In addition, having all your flowerbeds and lawn areas on a timer eliminates the need to drag hoses around your yard, freeing up time for more important things.
I also recommend to my customers to install a Smart controller, which offers a couple different water-saving options. The first option is a dedicated WIFI connection to local weather stations. Other options include wireless rain sensors and wireless in-ground sensors. Both units sense when it is raining or your lawn has reached a certain saturation point and actually limits the controllers watering time or in some cases, stops the watering all together.
I recommend using all 3 options because it saves my customers even more money!