San Diego water bills would rise nearly 20 percent under a rate-increase proposal the City Council is scheduled to consider Tuesday. The increase, which city officials began studying last fall, would be the first comprehensive rate hike approved by the council in nearly eight years. It would include a 10.2 increase this December and an 8.75 percent jump in January 2025. City officials say they need additional revenue increases to cover rising costs for imported water, upgrades to thousands of aging pipes and a long list of short-term and long-term capital projects. The capital projects include the Pure Water sewage-recycling system, which has been under construction since last year, and upgrades needed to several aging city dams that state officials have deemed in poor condition.