Oahu’s low flush toilet rebate program is due to end this year.

Since 1994, the Honolulu Board of Water Supply and the city’s Department of Environmental Services have been offering a $100 rebate to customers who swap their high volume flush toilets for ultra-low flush toilets.

The program was originally due to end in 2008, but the agencies extended it to save Oahu’s water supply and reduce the flow of water into the city’s sewer system.

The Board of Water Supply estimates the rebates have saved Oahu more than 4.6 billion gallons of water in the 16 years the program has been in effect.

The agency said in a news release yesterday that property owners wishing to receive a rebate must submit their applications to the board by Dec. 31.