San Francisco’s Board of Supervisors has approved an ordinance requiring drug manufacturers to fund and administer a take-back program for unused and unexpired medications, The Wall Street Journal reports. The measure awaits the mayor’s signature.

If Mayor Edwin Lee does not sign the bill by Friday, it will automatically become law, the article notes. If the law goes into effect, San Francisco will become the first major U.S. city to require drug makers to set up a take-back program.

The bill is similar to one passed three years ago by Alameda County, California. In October, a federal appeals court ruled drug manufacturers must pay for that program. The decision upheld a lower-court ruling.

The aims of the take-back program are to reduce contaminants in drinking water by giving people an alternative to flushing their medications down the toilet. Officials also hope the program will reduce prescription drug abuse by reducing the amount of medication in home medicine cabinets.

The pharmaceutical industry filed a lawsuit against the Alameda County ordinance, claiming it violated the Constitution by interfering with interstate commerce. The suit argued safe disposal of unused medications should be a shared responsibility, and that requiring drug companies to pay for the entire cost would ultimately result in increased prices for consumers.

The Ninth U.S. Circuit Court of Appeals in San Francisco ruled 3-0 that the ordinance treats all drug manufacturers equally and does not place a substantial burden on interstate business. The court noted drug companies generate $950 million in sales annually in the county, and could easily afford the cost of the program.

The Pharmaceutical Research & Manufacturers of America has asked the U.S. Supreme Court to review that decision.