A healthcare construction boom hasn't kept local hospital systems from adding to the $3 billion or so that they hold in cash reserves. Hospitals in general are saving more money, said Richard Gundling, vice president of the Healthcare Financial Management Association, based in suburban Chicago. Gundling cited data from Moody's that shows the median-rated hospital had 175 days of cash on hand in 2011, up from 149 in 2009. Highly rated hospitals typically have more money in reserve. Hospital and health-system officials said they need to grow their "rainy day" funds given the uncertainty surrounding the federal healthcare overhaul and the prospect of lower government reimbursement for the patient care they provide.