The city of San Diego is expanding its probe into complaints over mysteriously high water bills by checking the 250,000-plus meters across the city. City spokesman Jerry McCormick said the expanded investigation has already begun into both smart and manually-read water meters. The announcement comes less than a day after the city divulged that more than 300 families were overbilled by an average $300 in four neighborhoods – Carmel Valley, Rancho Bernardo, Mira Mesa and Rancho Penasquitos.