Effective the beginning of this year, California law requires all single-family residences built on or before January 1, 1994 to be equipped with water-conserving plumbing fixtures. Multifamily and commercial properties are given an extra two years before they need to comply.
The non-compliant water fixtures are any of the following:
(1) Any toilet manufactured to use more than 1.6 gallons of water per flush.
(2) Any urinal manufactured to use more than one gallon of water per flush.
(3) Any showerhead manufactured to have a flow capacity of more than 2.5 gallons of water per minute.
(4) Any interior faucet that emits more than 2.2 gallons of water per minute.
With that said, there is nothing in this state law that requires the installation of water-conserving fixtures as a condition of sale, though some local jurisdictions(counties or cities) may have their own ordinances dealing with these matters.