Which one of you put a water filter here?

You might want to ask who put the polybutylene supply lines here. That's some bad stuff and 28 years ago was the "pipe of the future" until it wasn't. Hope it was not used with high chlorine concentrations for extended periods of time.

It was that one kid who was afraid to drink water out of a garden hose and is still scared of their RV tank.
Yes that person exists.