Televised ducts under slab floor. Ducts are concrete with metal fittings and connections. There was standing g water in the ducts in the sunken living room g room area. Ran water in the kitchen sink and see water entering the pipe. Suspect a leaking elbow under the furnace. Suggest repairing the sink drain line then after that is done suggest spray lining ducts to encapsulate them because of contaminated water.