SAN FRANCISCO (AP) — A San Francisco lawmaker wants to require new buildings to use non-drinking water for flushing toilets and hydrating plants.

Legislation introduced Tuesday calls for many large new buildings to use gray water — wastewater from baths, sinks and other kitchen appliances — for toilet flushes and landscaping.

The plan would require private developers to create piping systems to capture and clean the gray water. Conservation advocates told the San Francisco Chronicle that they believe the requirement would be the first of its kind in the country.

“We need to be acting like we are in a crisis, because we are,” said Supervisor Scott Wiener, who introduced the legislation at the Board of Supervisors’ meeting. “We have a huge opportunity in California to reduce water use by aggressively moving toward water recycling.”

The Chronicle reports the proposal already has drawn criticism from some developers, who say it would add millions of dollars in construction costs when there are cheaper ways to save water.

“Good god,” micro-unit developer Patrick Kennedy said. “Everyone’s talking about bringing down the cost of housing, and that’s a big expense for something that might be achieved through a more benign way, like lower-flow toilets.”

The legislation would apply to new buildings that are 250,000 square feet and larger, and within certain areas of the city, including along the western border and the development-rich South of Market area. Buildings in these special districts already have some structures in place to pipe gray water.

According to San Francisco’s Planning Department, there are about two dozen new projects in the permitting process that would be immediately affected by Wiener’s legislation.

Michael Yarne, a San Francisco residential multifamily developer, said he supports the idea in principle. That people use clean drinking water for toilets and landscaping “is absurd,” he said.

“The challenge is, how do you bridge over to such a system that allows the development community to afford those costs?”

The proposal also calls for city departments to use gray water to scrub down and irrigate public spaces such as parks and plazas within five years.