Is it unpleasant to drink UV-treated water that still contains bacteria and microbes , even if they are dead ? How do you remove them?

None of existing disinfection methods removes treated microorganisms from water, it is not necessary. The total mass of bacteria in water before disinfection could be around 0,0001 milligram per one litre. Bacteria, viruses and protozoa treated by ultraviolet become just simple organic compounds not hazardous for human. Standards allow lewels up to 1 milligram per litre or ten thousends or so times more than mass of dead microorganisms after UV disinfection.