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.
Your tap water probably contains more minerals and your household filter does not remove them completely. (maybe your household filter is not working properly).
Bottled water use industrial food grade filtering techniques, they work better than home filters.
You could ask your city about the mineral content of your water, it should be
publicly available.