Two-Step Disinfection

The lapse in blogs, and please forgive me, arose from classes starting back at Central Wyoming College where I teach. I was asked today about two-step water disinfection processes. There are several, but of specific interest this afternoon was the combo of filtering and adding chemicals. Which should you do first? No hard science tells us. Here are some thoughts: If you use your filter first, you'll remove quite a few "things," including larger germs, leaving your chemical with less demand being put on it. Speaking much more practically, it's simple to filter some water, say, out of a lake, and then add a chemical. Not so easy, it is, to collect water, add a chemical, and then, after waiting the appropriate amount of time, use a filter. But throw this into the mix: if your filter has a charcoal (carbon) stage, using the filter second will remove the unused chemical--and its taste and smell.