Thanks for all the good suggestions - I tried all those while at the campsite, no improvement. Only portable water with pump worked. This morning after I left our site, I moved to a nearby site slightly lower than ours (by ~ 20 ft), the water pressure was fine! We camped at top of a hill and water comes from a tank that's higher than us. I don't believe the pressure drops so much from a lower to a higher site. But apparently the back pressure from RV reduces the flow. Again, at tap the water flows just fine, but there is no back pressure. At this point, I've stopped worrying.