I'm not claiming to be a water filter expert but UV is only intended to kill bacteria. A particulate filter will take out particles. A charcoal filter will absorb some but not all chemicals (including oder producing chemicals). Combine these to get all three.
No matter what, an under the sink filter is not going to cut it with a cistern, you need whole house.
Anything and everything including any chemicals that land on your roof (or chemicals that leach form your roof) will go into the cistern other than what the screen catches. Those chemicals could come from upper atmosphere, car/truck exhaust, pesticide overspray, WAPA plant, used to be Hovensa plant, etc. So you'd need something like a reverse osmosis or distillation filter if you want to remove all the chemicals as well as the other stuff. Reverse osmosis is what they have in all the rainmaker machines I believe.
Of course you can get away with basic whole house UV and particulate filtration for the bulk of your water and use a smaller under or over the counter reverse osmosis filter for consumption. Swallowing a little water from a UV/particulate filter while brushing your teeth shouldn't be a problem.