Residue in a cup of tea using household filter

I’d like to ask some insights re potential cause of residue in a cup of tea when I used water from household filter but no residue when I used the water bought from purified water vendor. I boiled the water from both sources and used the same tea bags. The filtered water showed lots of residue while no tea residue using the water that I bought. Both of them were very clear before dipping the tea bag. Hope you can shed some light.