My home was built in 1980. The water supply is from a well water system. In the room where it runs into the house, there is also a pressure tank and a water heater, both of which look to be from the late 80s. During showers, there is a short, yet distinct pressure “spurt” followed by a blast of cold water, which definitely wakes a guy up in the morning! What is the cause of this and how can I fix it?