If you are on city water you just may have low city water pressure. You can buy a pressure test gauge at Home Depot that just screws on to a hose or the water faucet at the park. If the pressure is low, just fill your fresh water tank and operate off of it with your onboard water pump.
You should also get a pressure regulator. The park where I was this summer had high pressure that I didn't want to ever get to the plumbing in my 5'er. It was mostly in the 80-85 psi range. I have my regulator set at 50 and I'm happy.
2006 GMC 2500HD CCSB 4x4 Duramax/Allison, Titan 52 gallon fuel tank, Prodigy Controller, B&W Companion Hitch
2010 Jayco Designer 35RLTS, Cummins/Onan RV QG 5500 EVAP, Progressive Industries EMS-PT50C, TST Systems 507 TPMS, RV Flex Armor Roof