I have been using it for years and it works fine for me. Is it possible that your water is so hard that the filter can' t handle it?
I doubt it's too hard. It's Philly city water. When I was a teen I lived in Meford NJ and we used well water. That was hard. It would constantly leave rings and stains. Taking a shower was tough too as soap would hardly suds up.
I just didn't like it. I would also guess it was a closeout from stock they had on hand.