Did you flush it through with a litre or two first? possibly a viral infection as these type of filters do not do well against sub 0.1 μm viri, only Halogens or heating >56deg. C. will sort them out.Tried one of these last year and got pretty sick for about 48 hours - vomiting etc. Was using one of those things and not sure it does a good a job as they claim? Unless just coincidence maybe.