Izzy: "I prefer to chemically treat very dirty water and then boil."

Why? Boiling is the surest way to kill everything. Adding chemicals only wastes time and money, and puts unnecessary chemicals in your body.

As far as treatment times, bacteria and virii are killed in 15 min regardless of temperature, Giardia and Crypto take between 30 min and 4 hours(with Giardia being killed much faster), but the latter is a worse-case scenario for cold, dirty water. Unless the water seems really sketchy, I would usually take my chances after 30 min.


In response to the original question, I'm pretty sure you can double the dose and drink the water safely-much if not most of the chlorine will evaporate anyway, espcially if you shake up the bottle and then let it sit with the cap open for a bit. That's one of the nice things about chlorine dioxide as opposed to chlorine.
It's actually a good idea to double the dose if youre treating very dirty water, or if your water is very cold and/or you don't want to wait as long. There should be a slight chlorine odor when you open the bottle, if not, you probably need to add another tablet.