Thanks for pointing me to the check valve in the pump. I was hoping there was a manual pump somewhere that I had not turned. The trailer was winterized (supposedly) when I bought it on December 23,2011(leess than 6 months ago) however the first time I went to use the trailer in April the clear water filter container broke off at the ring at the top where it screws on; so I suspect that it actually froze sometime over the winter, leading me to think the sticker in the window saying unit has been winterized was not accurate. I already had the dealer pay for the new water filter so maybe the pump froze also and the ruined check valve? The bad thing is the nearest dealer is over an hour and a half from me.