2014 Berkshire 390FL water filter

[wdweldon]

What model number of water filter do I use and should I also install a in-line water filter to use with the hose?

[RKNOLA]

The model number should be right on the filter they buy from Amazon. Some models can only be bought from an RV store. An in-line water filter is going to be personal preference depending on whether or not you want to drink from the faucets.