@BoredSysAdmin
In Austin proper, all of the utilities (power, sewage, garbage, water) come on a single bill, so I rarely even look at the water supply charges only, I just look at the total bill.
I can tell you now, it is NOT the water for the lawn that will be the big $ on the utility bills. It IS the power to run the AC that will be the largest part of the utility bill, by far! Texas has brutal summers, brutal!
Over the Texas summer, you will need to water the yard to keep it looking decent. But, it is also very common that we hit stage 1 or stage 2 water restrictions depending on lake levels. The first restriction is only able to water 2 days a week. Then, it goes to 1 day per week and then restaurants can't just give you a glass of water unless you ask for it. So, the $ spent to water your yard will be kept in check due to the watering restrictions too.
The real answer here is that you really need to be looking at native plants and grasses that are drought tolerant, and looking to landscape areas so that the yard won't require as much water over the summers. The reality is, that is the only approach that really makes any sense.
I have a 1300ft2 house on a 0.1 acre lot. My total utility bill is usually around $200 over the winter, but during the summer it can go as high as $400. But, when I am actually at home, I don't like the house temperature to be above 72F. I'm OK with paying for that luxury.