In the great city of Dallas we have a lot of cheap water. Even when we have droughts and the reservoirs get low, the price doesn't go up.
Just three hours south we have the city of Austin and they don't have near enough water. They understand water conservation better than most, and, they are the capital of Texas. Their city hall is Xeriscaped, ours has a big fountain.
So laws and regulations that come out of Austin are often aimed at conservation but the City is responsible for enforcement. Somewhere between Austin and Dallas on I35, water conservation falls off the truck.
The City can put in place its own policies and ordinances and they have. There are limits as to when you can sprinkle...(all night every night). Unless you hand water or use soaker hoses...you can do that 24 x 7. And, to really put the fear in the citizenry you absolutely aren't allowed to water during rain or freezing weather.
On the incentives side, the city has some programs to help conserve water. First, their biggest program, you can get $90 to change out your toilet out for a low flow one. From the City's web site...
"Water conservation is a major component of the City’s long-range water supply plan. Our goal is to save 3.5 billion gallons over the lifetime of the 20,000 toilets replaced in the next five years through this program. "
Now that means they are going to save 175,000 gallons per toilet. I will be generous and allow two gallons a flush savings. That single toilet will have to flush 87,500 times in its lifetime to save that much water. If you figure five flushes a day that's about 48 years. 10 flushes (twice our amount), 24 years, or, 20 flushes a day (a family of five home all day with one toilet?) for 12 years!
Of course we have to assume they won't remodel or upgrade that toilet again later.
Now take my sprinklers. I have saved 51,000 gallons in seven months. I will surpass the toilet's lifetime savings in 17 months. In fact, at that rate, in 24 years I will have saved the equivalent of 12 toilets. For us personally, we each use the toilet five times a day and flush less, with two toilets. That means my five flushes a day toilets, upgraded, would take 48 years each to meet the 175,000 gallons city target.
At that rate I will have saved 24 toilets worth of water. My savings cost around $2000. The same toilet saving will cost the city $2,160 and the homeowners around $100 each to install and another $100 average to purchase because cheap toilets don't qualify for the rebate. That adds another $4800, so $6,960 total, about three times my cost per gallon. And of course that doesn't include the administrative costs for the geniuses at city hall to run this program.
You should also bear in mind all those removed toilets are land filled.
Bottom line - upgrading your toilet is a good thing. After about ten other things that have a lot better ROI and water savings potential. The City is almost preying on unsuspecting water consumers who want to be water conscious by leading them to believe this is a good first step. It's not.
So fix your sprinklers, lower the pressure, put in new multi-stream nozzles, get an ET controller, add drip when redoing beds. Inside the home, add flow regulators to showers, change all the aerators on all the faucets, stop drips and flush a little less. You'll save a lot more water and money than calling your plumber to install a new low-flow toilet.
And, for you do it yourselfers out there. Changing out a toilet is relatively easy. A leak however from the connection to the wall, the valve, the tank, etc, can all be catastrophic. There is nothing to safeguard you from flooding your house during a simple weekend trip away. (And they always break when you're away.)