It's a risk if you don't swap the filter regularly as recommended by the manufacturer, and everything downstream of the filter (tubing etc) is at elevated risk for biofilm buildup when the filter is stripping out chlorine/chloramine.
It's an even bigger risk, generally, with pitcher/reservoir type systems (e.g. Brita or Pur) that require manual fills, given that they get a lot of environmental exposure. If you use a Brita pitcher for a while and then leave the filter media and pitcher somewhere at room temp for a couple weeks, you can often see evidence of fungal/microbial growth popping out of the bottom of the filter cartridge. It's pretty gross. I've also had a relative end up in the hospital with a pretty severe amoebic infection, which investigators traced back to her Brita filter cartridge she had neglected to change for some time.
Part of the reason I purposefully bypassed the filter on my fridge. The tap water is fine and doesn't need filtering but an old water filter can cause all sorts of nastiness.
It's really shocking how ineffective things like pitcher filters are when compared to a quality cartridge filter. The pitcher filters really do practically nothing.
There's no question that Brita filters improve water taste by reducing chlorine/chloramine levels, and they will remove relatively large particulates, but they pale in comparison to proper pressure-driven cartridge filter systems if you start looking at comparisons for other contaminants.
Sure, but for people who are getting perfectly safe water from their municipal water supply, and just want to get rid of the chlorine taste -- that's where pitcher filters work perfectly. You don't need anything else.
It’s still probably not doing anything, chlorine readily evaporates out of water left in a pitcher. It’s a common technique used by indoor growers of certain plants - leave a bucket out for a day.
I can taste the water 5 minutes after it goes through the filter. The chlorine is gone. (Which is not the case if I pour it into a glass.) It has nothing to do with how long it sits around for.
I find it strange you're insisting filters don't work when one can tell from taste that they clearly do. And scientifically, activated carbon absorbs chlorine -- that's not a myth. So everything checks out.
Sure, they work for chlorine, but there are plenty of other issues (arsenic, PFCs, other VOCs, glyphosates, TTHMs, lead for non 'Elite' Brita filters) that Brita filters are woefully inadequate to address.
It's an even bigger risk, generally, with pitcher/reservoir type systems (e.g. Brita or Pur) that require manual fills, given that they get a lot of environmental exposure. If you use a Brita pitcher for a while and then leave the filter media and pitcher somewhere at room temp for a couple weeks, you can often see evidence of fungal/microbial growth popping out of the bottom of the filter cartridge. It's pretty gross. I've also had a relative end up in the hospital with a pretty severe amoebic infection, which investigators traced back to her Brita filter cartridge she had neglected to change for some time.