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.

  • A water filter does not remove limescale, you need a water softener for that. Jug-style filters do a bit of both, but a whole house mains-water filter is likely a filter only. Can you clarify what system you are using? BTW, mineral content of bottled water varies dramatically by manufacturer, so you'd need a detailed analysis, usually printed on the bottle, to accurately compare.
    – Tetsujin
    Mar 29, 2021 at 11:13

1 Answer 1


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.

  • Thank you for your insights. I actually use 2 sets of water filter that I bought from local online stores. The 1st one is connected to the faucet and has 3 cartriges: Sediment filter, mineral filter then Activated Carbon The second is a water purifier with dispenser that has ceramic filter then a cartridge with different mineral sand and stones. Just to be sure, I'm also boiling the water for drinking. I'm sure that with these process we're drinking safe water but I'm just curious why i see lots of tea residue when I used this water vs when I used purified water bought outside. Mar 30, 2021 at 0:54

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