Just checked the history on our water bills, and it looks like we pay about $120-$140 every *two* months during the summer (averaging, as we pay every month). During the winter, it runs about $100-$120 every two months. This is for a family of five, and a ~9,000-10,000 sf lot with a fair amount of grass.
It’s interesting to go through it this way, because it would seem to indicate that we don’t water our lawn very much, which is true, now that I think about it. It helps greatly that we have a lot of large trees that keep the ground moist and cool, which means we have to water a lot less often. Also, we don’t live in an HOA area, so while our grass is always pretty green, it doesn’t look like a golf course. 🙂
Sounds to me like you might want to scale back on the landscape watering and see how that goes.