What is the latest view on fresh water filtering. My van has a Nature Pure Walter filter which hasn't been changed for a few years now - due to lack of motorhome use. From 'Pure Water Online' the 400009 Nature Pure Ultrafine Cartridge is now over £100. I know there was some controversy a few years ago - so just wondered if there were any thoughts before I decide whether to proceed with the £116 including delivery spend, or whether to look for a different solution? Thanks