The problem with filters is that most people either never change them, or only once per year.
They are supposed to be changed after a certain number of litres of water have gone through them, which may be frequently for owners who use the van a lot, or very infrquently for those who dont.
The danger is, water left in any container goes sour, or stagnates, and then provides the perfect breeding ground for bacteria.
Having seen the state of many filters, I wonder how the occupants have survived for so long,,they have been disgusting.(the filter, not the owner!)
The other problem is that they are prone to split in freezing weather, such as we have had, and the first the owner knows is when the van floods.
Personally I believe they are more troublesome than they are worth and certainly present an unnecessary health hazard.
I recommend my customers to dispense with them completely, and for the in line type, substitute a piece of pipe in place.
For the Crystal type, just remove the filter from the clear plastic end cap and refit the cap alone.
The water quality in the UK and most of Europe is excellent and a filter is not required, but is an expensive "extra" which gives a false impression of doing something, which it does NOT.
We use our van a lot and always use the on board water or aquaroll water, unfiltered, and have never had any ill effects whatsoever, here or abroad.