Durham, N.C. — The city's Department of Water Management has launched a program to provide $100 rebates to local residents who replace old toilets with models that conserve water.

The city will spend about $300,000 on the program, which officials said could save Durham 21 million gallons of water a year.

Only single-family homes are eligible to receive the rebates, which will be issued on a first-come, first-served basis, officials said. Homeowners must purchase high-efficiency toilets bearing the U.S. Environmental Protection Agency WaterSense-label to obtain a rebate.

“Toilet flushing makes up about 30 to 40 percent of all water used in homes. Older, inefficient toilets can use between 3.5 and seven gallons per flush and are responsible for most of the water wasted in our homes," said Vicki Westbrook, deputy director of the Department of Water Management. "Recent advancements have allowed toilets to use 20 percent less water than the current federal standard of 1.6 gallons per flush, while still providing equal or superior performance."