The Naked Scientists

The Naked Scientists Forum

Author Topic: Why does bottled water start to taste bad when I leave it open?  (Read 4699 times)

Offline thedoc

  • Forum Admin
  • Administrator
  • Sr. Member
  • *****
  • Posts: 511
  • Thanked: 12 times
    • View Profile
Dr Ronacher, K,  asked the Naked Scientists:
   
I take a bottle of filtered water with me to work everyday. The water tastes fine when i fill my bottle.

Once at work i have realise that if i leave the bottle open on my desk for a few hours the water tastes really bad of chemicals. If i leave the bottle tightly closed this does not happen, so it cannot be chemicals leaching from the bottle into the water.
I have tested this now many times and always make the same observation.

My office is adjacent to laboratories and we share the same aircon system. I was wondering if the water in my bottle could absorb chemicals from the air. There is no obvious smell of chemicals in my office and despite being a biochemist myself i am not able to judge by the taste of the water what chemical it could be.

I have searched the literature a bit but could not find any evidence that chemicals in the air can be absorbed by water.

Do you have any explanation for this?

Katharina


What do you think?
« Last Edit: 21/07/2015 14:50:01 by _system »


 

Online Bored chemist

  • Neilep Level Member
  • ******
  • Posts: 8667
  • Thanked: 42 times
    • View Profile
Did you drink from the bottle before you left it open?
 

Offline Ethos_

  • Neilep Level Member
  • ******
  • Posts: 1277
  • Thanked: 14 times
    • View Profile
"Ronacher, K, Dr  asked the Naked Scientists:
   
I take a bottle of filtered water with me to work everyday. The water tastes fine when i fill my bottle.

Once at work i have realise that if i leave the bottle open on my desk for a few hours the water tastes really bad of chemicals. If i leave the bottle tightly closed this does not happen, so it cannot be chemicals leaching from the bottle into the water.
I have tested this now many times and always make the same observation.

My office is adjacent to laboratories and we share the same aircon system. I was wondering if the water in my bottle could absorb chemicals from the air. There is no obvious smell of chemicals in my office and despite being a biochemist myself i am not able to judge by the taste of the water what chemical it could be.

I have searched the literature a bit but could not find any evidence that chemicals in the air can be absorbed by water.

Do you have any explanation for this?

Katharina


What do you think?
I'm not a Biochemist but it occurred to me that leaving the bottle open might allow the oxygen content of the original contents to dissipate. Understanding that higher oxygen concentrations may improve the taste of the water, allowing this concentration to lessen may be the reason for the diminished quality regarding it's taste. Just a thought???
 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4123
  • Thanked: 245 times
    • View Profile
Dust and spores in the air can fall into an open container, and that might leave some taste.

If it is filtered water, there won't be a food source for bacteria or fungi to grow and thrive. However, photosynthesising algae could make a living there if the bottle were left in bright light.
 

Online Bored chemist

  • Neilep Level Member
  • ******
  • Posts: 8667
  • Thanked: 42 times
    • View Profile
Understanding that higher oxygen concentrations may improve the taste of the water,...

How?
Pretty much all the water you taste has oxygen in it.

The reason I asked about drinking from the bottle is that, while it's true that dirt and spores might fall into it from the air, it's pretty much guaranteed that bacteria and saliva will get into it if you take a drink.
 

Offline Ethos_

  • Neilep Level Member
  • ******
  • Posts: 1277
  • Thanked: 14 times
    • View Profile
Understanding that higher oxygen concentrations may improve the taste of the water,...

How?
Pretty much all the water you taste has oxygen in it.


Check out the last paragraph in this article where it says:

"A high DO level in a community water supply is good because it makes drinking water taste better"

http://www.lenntech.com/why_the_oxygen_dissolved_is_important.htm
« Last Edit: 24/07/2015 03:38:06 by Ethos_ »
 

Online Bored chemist

  • Neilep Level Member
  • ******
  • Posts: 8667
  • Thanked: 42 times
    • View Profile
i didn't ask for an unevinced claim from a group who claim to solve the "problem" and are effectively paid to make stuff up..
 i asked for an explanation.
 

Offline Ethos_

  • Neilep Level Member
  • ******
  • Posts: 1277
  • Thanked: 14 times
    • View Profile
i didn't ask for an unevinced claim from a group who claim to solve the "problem" and are effectively paid to make stuff up..
 i asked for an explanation.
I recommend you write to the folks that wrote the article and ask them for that explanation.
 

Offline chris

  • Neilep Level Member
  • ******
  • Posts: 5339
  • Thanked: 65 times
  • The Naked Scientist
    • View Profile
    • The Naked Scientists
This drinking water in a bottle question is a slightly tricky one to solve because there are multiple confounders here.

However, if we consider what might change about the water during the day:

The temperature is likely to increase; warmer water will hold dissolved gases less well and hence de-gas itself, because warmer liquids hold less dissolved gas than cooler ones. If the lid is left on, and the bottle is full, then the extent of degassing is likely to be less than with the lid off. Oxygen will certainly exit, and dissolved oxygen is known to contribute to perceived taste.

Second, leaving the lid off makes absorption of CO2, and it's conversion via carbonic acid to bicarbonate ions, more likely; the water will act as a CO2 sink and slighlty acidify over time. This has a more pronounced effect on flavour and taste.

As to other chemicals entering or leaving; it's certainly true that airborne material will enter the water if the lid is off. Whether this will affect the taste depends upon the impact of that material on the water chemistry, and/or our ability to taste the products of that interaction.

I'd suggest two things: 1) switch to a glass bottle for starters, unless you're fond of drinking plasticisers, 2) keep the cap on!

Chris
 

Offline Ethos_

  • Neilep Level Member
  • ******
  • Posts: 1277
  • Thanked: 14 times
    • View Profile
If the lid is left on, and the bottle is full, then the extent of degassing is likely to be less than with the lid off. Oxygen will certainly exit, and dissolved oxygen is known to contribute to perceived taste.


Thank you chris, all interesting information........
 

The Naked Scientists Forum


 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums