A visual representation of critical opportunities in water conservation, efficiency, and supply is available from green-building and water-conservation consultant Jerry Yudelson.

“Pyramid of New Water Sources” organizes 10 opportunities for extending urban water supplies heading into a hotter and drier future:

  1. Changing behavior via such measures as public education, effective water pricing, water audits, and Web-based information.

  2. Low-cost/no-cost measures, such as fixing leaks and retrofitting fixtures.

  3. Irrigation measures, including native plantings and drip irrigation, along with smart irrigation controllers.

  4. Hygiene, such as water-free urinals and high-efficiency toilets.

  5. Water-conserving appliances, such as dishwashers, water softeners, and clothes washers.

  6. “Extreme makeovers” that include composting (no-water) toilets, hardscape (unplanted) landscaping, and on-site blackwater treatment and reuse.

  7. Water heating, including hot-water recirculation loops, efficient water heaters, and solar water heaters.

  8. On-site reuse, including rainwater and graywater collection and reuse for irrigation.

  9. Off-site reuse using reclaimed water from “purple pipe” systems and “sewer mining” (treating sewage already flowing in pipes).

  10. Desalination of seawater and brackish water and new water sources, such as potable water created through reverse-osmosis treatment of reclaimed sewage.

The founder and president of Yudelson Associates, Yudelson is the author of 12 green-building books, including “Dry Run: Preventing the Next Urban Water Crisis.”