Nearly 240,000 residents in parts of southeastern San Diego County will soon see higher water bills.  The Otay Water District notified customers that it will implement an 8.3% rate increase effective Jan. 1, saying the “unavoidable” hike is mostly due to charges passed down from its wholesale water suppliers: The Metropolitan Water District of Southern California and the county Water Authority. … Otay Water officials said the vast majority of the increase is tied to costs from suppliers, which have seen higher labor and energy costs and inflation, while also bringing in lower water sales due to drought conditions.