Water will be rationed throughout Southern California as the region nears the beginning of its fifth year of drought.

The Metropolitan Water District, which serves 15 million customers in six counties, will fine cities and other agencies it supplies if they surpass limits approved Tuesday.Residential use must be trimmed by 5 percent, and farm suppliers face 20 percent cuts beginning Feb. 1. Local agencies that go over the limits will pay tripled fees.

The limits directly affect local suppliers, not the 15 million households, businesses and farms the district serves in Los Angeles, Ventura, San Diego, San Bernardino, Riverside and Orange counties.