First I do have an outlet to fill the freshwater outside the trailer. The water is overflowing and dripping out this outlet unless I open the drain.If the back flow valve is in the pump I will probably replace the pump. (the trailer is over 10 years old). Any suggestions on pumps? Will use the pump infrequently. I will be putting this trailer on my seasonal site this fall for good replacing my 25 year old Holiday Rambler(gotta love the HRs). I will use the pump when the park shuts off water for the winter for a couple of weeks.