Yes that is the valve. One way allows draw from fresh water tank. Other way allows you to draw antifreeze from bottles. I have a 2011 210 w b s and have been doing this every year. Make sure you empty water tank first. Then turn pump water out of the line. Allow pump to pump air for a second first or or you may wish you had. I forgot one year and cracked the hose from freezing. Older hose has an inner lining.