Some thoughts on this issue - FWIW -
On our Solera - and, I suspect, on most RVs - the internal water filter is plumbed AFTER the water pump - therefore after the check valve which prevents city water from flowing into the fresh water tank. As such, any sand, dirt or other material in the incoming water can enter the check valve and cause it to leak. I believe using a filter at the hose spigot can significantly reduce the incidence of this problem by keeping such crud out of the check valve.
2012 Solera "S"
Calif SF Bay Area