Rebates for replacement: On top of the traditional structure markets, the replacement market is flourishing. Rebate programs to encourage the installation of low-flow , 1.6 gallons per flush (gpf) toilets, such as the three-year, $300-million effort in New York City, are being considered by a host of different municipalities, too. "Cutting the total amount of water cuts the need for new sewage-treatment plants," Srenaski states. "I believe that is an isolated but growing trend."