I would still filter the water before drinking it. I think 1 drop CDS per liter should be enough to disinfect water (please correct me if I'm wrong), but you can't get coarser dirt and heavy metals out of the water, so you should still use a water filter.
From experience I can say that this water filter (unlike many others) can really lower the PPM value of the water drastically.
www.amazon.com/FS-TFC-Super-high-Precision-Purification-Preparedness/dp/B087N3P6Q2/ref=sr_1_1?dchild=1&keywords=water+purifier+0%2C0001+micron&qid=1617556969&sr=8-1
And I would first disinfect the water with CDS and then filter it, in that way you can really be sure that you do not have to drink dirty water on camping or trekking trips. By the way, rainwater is "relatively" clean (with us/Germany it has about 9 PPM), although it also depends on the location and where you are (so keyword air pollution/chemtrails etc.).