Congrats on your excellent germination rate.

I should mention though that I've had very high germination by scarifying/chipping seeds, soaking for 24 hours in regular tap water and planting in soilless mix. The chlorine/chloramine wasn't an issue (is chloramine removed by filtering and boiling?).

The filter/boil/cool regimen worked for my yeastbreads, so I think it's the trick. I also use Brita filtered water on all my seedlings. Maybe it's a bit obsessive but I feel better safe than sorry.

chlorine isn't stable, so if you just let the water sit out for 3 days, it should all dissipate. Chloramine, however, persists; I know there are chemicals used in ponds to remove it, but haven't tried any.

Agreed, not all forms of chlorination are volatile (able to evaporate.) The info about letting water sit persists from a time when most municipalities used a volatile form. Now, most do not.

Rain, distilled, and condensate from dehumidifier or A/C are sources of water with no chlorination (or ground water minerals, like lime.)