Jadnashua
Retired Defense Industry Engineer xxx
In 1994, it became illegal to manufacture a toilet that used more than 1.6g/flush, limited the water use for vanity and kitchen sink faucets, and other restrictions. Many states have adopted stricter laws, and you should check with your local inspector about what is required where you live. This link at the end has a listing by state of the current (as of date of posting) rules regarding what you can and cannot do with regards to remodeling or new construction. Some of the states prohibit sale, import, or installation of any plumbing fixture that does not meet certain rules. Some have more stringent requirements than the federal rules. Not knowing what is required could cost you a lot of grief. There are some companies that make qualifying stuff that looks retro, so if that's your goal, it is likely a better choice. California is considering a mandatory retrofit of non-compliant fixtures.
http://www.ncsl.org/research/enviro...ter-efficient-plumbing-fixtures635433474.aspx
http://www.ncsl.org/research/enviro...ter-efficient-plumbing-fixtures635433474.aspx