ALL RV's including yours, The City Water from the CG supply bypasses the Fresh Water Tank and goes direct to your Fresh Plumbing system. To get water to the Fresh Tank, you have to open a valve while on City water to fill or on your 20 year old, you may just have a gravity fill you stick the water hose in. BUT, Most Monaco's have the valve to use the City water to fill the tank. They also have the Gravity fill in your year. You have 2 ways to fill the Fresh tank. This link shows a 2001 Dynasty, but yours should be similar look at page 144. Doug
http://www.monacocoach.com/partsandservice/manuals/2001_Dynasty.pdf