Forgot to buy filtered water last time I made a batch and just used straight from the kitchen tap. Was sure I ruined it but it bubbled up like crazy in just two days. Gave it a taste and it was actually really sharp and good, kind of a nicer fizz to it. Guess my city water isn't trying to kill the good bugs after all.
That "nicer fizz" part got me. I've always been paranoid about chlorine taste and used bottled. But seeing yours bubble up like that, and now @shane327 saying his is fine too, maybe I've been wasting money. I'm gonna try a small test batch with my tap next time.
Totally get what @blair_chen81 means about the fizz. Same thing happened here last month. Ran out of my usual jug and just used straight tap on a whim. Waited two days, looked inside, and it was already super active and foamy. Tasted super crisp, no weird flavors. Maybe city water isn't the enemy for this stuff.