The Future Will Have Less Grass

According to Denver Water, household water used breaks down as follows:

54% landscaping
13% toilets
11% laundry
10% showers and baths
6% faucets
5% leaks
1% dishwashers

The most painless way for most households to cut water useage is to reduce the amount used on landscaping.

There will be pressure as Colorado and other parts of the arid west grown the water supply of the region. But, simply reducing landscaping water use can increase the carrying capacity of the Denver metropolitian area from a water perspective by up to about a million people.

Legalizing gray water systems to allow toilets to use recycled water not fit for cleaning or drinking could stretch supplies even further.

This set of statistics doesn't show it, but xeriscaping golf courses (or eliminating them), discontinuing irrigated agriculture in places where it is marginal, and increasing the efficiency of irrigated agriculture through steps like replacing broadcast sprinkling systems with drip systems, also leave lots of room to strech our current water resources further.