I would wonder about e-coli in the lake. If there's a lot of birds in the area, esp. geese, the e-coli level can rise to unsafe levels in the summer. I know a lake on Vancouver Island where that happens sometimes. It may look okay at the time of a water quality test but can change.
Doulton makes some excellent ceramic cartridges with a 1 micron rating. They have excellent info on everything you need to know about contaminants and filtration
here.As noted, Crypto & Giardia are chlorine resistant. Also note that it only takes one bacterial cell to get into a holding tank to multiply.
Another option is using an ultrafiltration ("UF") cartridge that is rated at 0.2 microns and will remove bacteria and most viruses. We have a 4-stage cartrdige setup using 10" cartridges, ending in a UF filter made by Crystal Quest.
On smoking, Winston Churchill smoked cigars non-stop and he lived to 90. DW's mom died from cancer from 2nd hand smoke in her fifties.