I don't recall the question ever coming up, and I've never had to live with a septic system, so I don't know, but does using pool water with a septic system cause problems? Specifically, the composition of pool water is different from tap water, and it seems that too much pool water could significantly affect the complicated balance of microbes that a properly functioning septic system relies on.

Obviously, for most situations, short-term sanitation trumps the long-term health of your septic system, but I'm just curious what using pool water does (or doesn't do) in this case. Or, when the emergency passes, maybe some remedial work needs to be done on the septic system that people aren't aware of needing after using pool water to flush their toilets?

Actually, I thought of this question while reading about the question of giving horses pool water to drink--horses rely on gut bacteria more than humans (although not as much as true ruminants, like cows), and if the pool water wrecks that balance, it would seem that their digestion/elimination could be negatively affected, like leading to colic, as was mentioned.