Obviously it's going to depend on how much water you think is in the unit, typically if we suspect there's quite a bit we will drain and replace the oil. After the replacement oil is in the unit we will usually run our filtration cart for a few days with water filters in it to ensure all the water is gone. It all depends on how the water entered the unit and if the pump ran with water in the system. Sometimes a drain and replace is sufficient but if It's under contract and we know the unit ran with water it in, a valve replacement is typically done to cover our end of the deal so we don't get stuck with future valve problems at our expense. It's always a good idea to inspect the valve for pitting and water damage if you have suspicion the unit was operating with water in the oil. Best of luck, and if it's just an open order job I'd say replace the oil and put It back in service after the water source is detected o course.