The tap water is drinkable, you just wouldn't want it to be your primary source of drinking water. Anyway, growing up middle class in the 80s and 90s, we had a

The tap water is drinkable, you just wouldn't want it to be your primary source of drinking water. Anyway, growing up middle class in the 80s and 90s, we had a filtered water spout on our sink. If you weren't poor, they were fairly common. Once lead was removed from the supply lines, we still continued to use them since it also stripped out chlorine etc. My point is, work-arounds for leaded drinking water weren't impactful enough to cause crime themselves. If you want to attribute a drastic decline in violent crime to drinking glasses filling slightly faster you're going to need some extraordinary evidence.