I found this for a 2003 model which should be similar to yours. If you don't have the manual do a google search and you will find a PDF version to print or save.
A five-gallon portable water container is located inside the cabinet nearest the sink. A 3/8" non-pressure hose is attached to the container.
2. A ten gallon water tank may be permanently installed in your camper. To fill the tank, open the lid as shown. (Fig. 4-1) Insert or hold the water hose and fill the tank to the desired capacity. The tank has an overflow outlet, but care must be taken to not overfill it.
3. Water may be received into the system through a direct hookup, referred to as “city water connection,” (Fig. 4-2) when attached to the entry supply and water hose.
Tank Water - place the handle into the vertical position, using short strokes.
City Water - move the handle down slowly to open the “CW” valve. Hold it in this position for quick use. Press the hancle down completely to lock it for continuous water flow.
IWARNING: The handle should be in the TANK WATER position when connecting city water to avoid acity water spill.