A combined tube set for a disposable water bottle for a medical instrument includes a cap with threads suitable for attachment to various water bottles. The combined tube set provides a first tube set for rinsing that includes an air and water tubes, and air/water connector The combined tube set also provides a second tube set for irrigation that includes an irrigation connector, backflow valve(s), and flexible tubing section. In some embodiments, the tube set can provide warm and/or humid gas to the endoscope.