If you don't use the shower (I assume there is a shower house where you are staying) and use the water only as needed (washing, washing dishes, and flushing) you should be good for 5 days. Otherwise, I don't think you can do it....
We usually camp in state parks where there is a tap nearby. I always end up hauling water in my 2 three gallon jugs or my 75' of water hose with a water thief adapter.