Legislation that would require most of Louisiana to add fluoride to public water supplies was sent back to the Senate for final approval Thursday.

House members approved Senate Bill 312 with an 80-16 vote. But since the measure was amended on the House floor, it has to return to the Senate.

SB312 would require water systems that have less than the minimum natural level of fluoride, and with at least 5,000 service connections, to estimate how much it would cost to install the equipment needed to mix fluoride with water. Once money is found through grants and state budget spending, the systems would then be required to install the equipment.

Rep. Kay Katz, R-Monroe, said more than six decades of research, thousands of studies and the experience of millions of Americans prove that fluoridation is healthy and economical.