Medium-term storage of water once jug opened?

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
Jh10000

#1: Post by Jh10000 »

Hello everyone,

First of all, I did use the search function but couldn't find the exact information I am now asking for, so my apologies if I'm asking a question that has already been answered. Simply link me the respective thread in that case.

I am considering buying water in 5-liter jugs, but do not plan on using more than about a liter per day. Right now it would be mineral water with the hardness and pH I want, but maybe in the future also distilled water and self-prepared re-mineralized water. I have three questions regarding this:

1. I have read that distilled water can be safely used for years after opening the container. Is this actually true, or is it a bad idea in practice? And does the taste become a problem if stored for too long?

2. Same question, but about mineral water. I would like to know if it's realistic to buy a 5-liter jug and use it over the course of 5 days, a week, or even two weeks.
My idea was immediately putting the content into five 1-liter bottles after opening the jug so that I have to only bring one bottle into contact with air frequently each time. Would this work, or will the taste and usability for coffee and tea deteriorate after I open the jug, no matter what?

3. Same question about self-made water made by re-mineralizing distilled water. Any way to store this for 1 to 2 weeks without health and taste concerns, and without issues related to the added minerals, like sediment forming?

Thanks a lot!

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LBIespresso
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#2: Post by LBIespresso »

I'm interested in hearing an answer to this as well. I usually mix up 2 gallons of distilled plus minerals and put them in 750ml glass bottles. I do this at 2 different locations so they can sit up to a month or so before use depending on where I am. I figure, since they are heated up to close to a boil it's safe and, well, so far so good :lol:
LMWDP #580

Pressino

#3: Post by Pressino »

I don't know the answer either, but I suspect the only ways water could "go bad" during storage is: 1) It is stored in a container made of a material (like some plastics and metals) that can leach undesirable substances or tastes into the water; or 2) It contains microorganisms and nutrients that allow them to propagate. #2 can be a significant problem with many water filters and is why some use UV sterilization gadgets.

A small quantity of inorganic salts well below saturation concentrations should not be a problem and should not precipitate out. Glass containers should be ideal for long term storage. Of course any container should not be left open longer than necessary, mainly to prevent evaporation and contamination from the outside.

Jh10000 (original poster)

#4: Post by Jh10000 (original poster) »

Thank you for the replies. I am overall not too worried about getting sick from drinking water from an opened container, but more about the water changing in taste.

Therefore, I was wondering if it is - taste-wise - a problem if don't use water from an opened jug very quickly.

Let's say I buy a 5l jug with the perfect GH, KH and pH, open it to remove some water, and then put on the lid again. Would the quality of the water change inside the container from the moment I open it?

Is there a consensus on this forum whether or not this is an issue at all?

Thanks!

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yakster
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#5: Post by yakster »

If your concerned about a change in taste, you should do an experiment where you use a 5 liter jug each day and on the fifth day compare the jug that you've been opening every day to one that you haven't been opening every day to see if you can taste a difference, then you'll have your answer.

There's no use asking someone else if they can taste the difference since it may not be the same for you.
-Chris

LMWDP # 272

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homeburrero
Team HB

#6: Post by homeburrero »

Jh10000 wrote:I am overall not too worried about getting sick from drinking water from an opened container,
That's good, because I don't think you'll find a clear consistent answer about that. Similar to the question about how long you should go between emptying and cleaning a machine's water reservoir.

Jh10000 wrote:Let's say I buy a 5l jug with the perfect GH, KH and pH, open it to remove some water, and then put on the lid again. Would the quality of the water change inside the container from the moment I open it?
The amount of hardness minerals (GH) and carbonates (KH) will not change other than by an insignificant increase due to evaporation of water, which leaves minerals behind while pure water evaporates.

The pH of an opened container may go up or down in some cases* but not in a way that affects the taste of the brew. The brightness/acidity that you taste in your brew is pretty much determined by the coffee's acidity and the alkalinity (KH, acid buffering capacity) of the brewing water.

Of course the taste quality of the water might even improve if your water is chlorinated, due to chlorine evaporating off. Or it could develop a bad taste if you get microbes growing in the bottle.


* (geeky details)
Given the relationship between carbonic acid and CO2:
CO₂(g)

CO₂(aq) + H₂O ⥃ H₂CO₃ ⥂ H⁺ + HCO₃⁻

there are a few situations where you expect a pH change after opening a container of water. One is water fresh out of the tap or a treatment system that has treated the water to be less corrosive, and has a higher than expected pH largely due to a lack of dissolved CO2. Once open and exposed to CO2 in the air, the water picks up dissolved CO2 and the pH goes down.

On the other hand, you can have water that has come out of a treatment unit that adds CO2, and in this case the pH may come up after opening the container and the surplus CO2 gasses off into the air. A mild example would be water that is fresh out of a WAC resin ( H⁺ exchange) softener. An extreme example would be water that has been spritzed with CO2 gas, as with a sodastream system. (Some coffee people actually have done this to get more mineral dissolved into their brewing water.)
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

Jh10000 (original poster)

#7: Post by Jh10000 (original poster) »

yakster wrote:If your concerned about a change in taste, you should do an experiment where you use a 5 liter jug each day and on the fifth day compare the jug that you've been opening every day to one that you haven't been opening every day to see if you can taste a difference, then you'll have your answer.

There's no use asking someone else if they can taste the difference since it may not be the same for you.
Thanks for the reply.

What I am curious about is whether or not the taste will - objectively - change, which has essentially been answered by the poster below you.

Of course it is a different question whether or not I can taste the difference, so naturally I will do the test you suggested as well!
homeburrero wrote:The amount of hardness minerals (GH) and carbonates (KH) will not change other than by an insignificant increase due to evaporation of water, which leaves minerals behind while pure water evaporates.

The pH of an opened container may go up or down in some cases* but not in a way that affects the taste of the brew. The brightness/acidity that you taste in your brew is pretty much determined by the coffee's acidity and the alkalinity (KH, acid buffering capacity) of the brewing water.

Of course the taste quality of the water might even improve if your water is chlorinated, due to chlorine evaporating off. Or it could develop a bad taste if you get microbes growing in the bottle.


* (geeky details)
Given the relationship between carbonic acid and CO2:
CO₂(g)

CO₂(aq) + H₂O ⥃ H₂CO₃ ⥂ H⁺ + HCO₃⁻

there are a few situations where you expect a pH change after opening a container of water. One is water fresh out of the tap or a treatment system that has treated the water to be less corrosive, and has a higher than expected pH largely due to a lack of dissolved CO2. Once open and exposed to CO2 in the air, the water picks up dissolved CO2 and the pH goes down.

On the other hand, you can have water that has come out of a treatment unit that adds CO2, and in this case the pH may come up after opening the container and the surplus CO2 gasses off into the air. A mild example would be water that is fresh out of a WAC resin ( H⁺ exchange) softener. An extreme example would be water that has been spritzed with CO2 gas, as with a sodastream system. (Some coffee people actually have done this to get more mineral dissolved into their brewing water.)
Thank you, that's just what I wanted to know!

If I understand correctly, that means that if the container in question is a bottle or jug of standard mineral water which I didn't modify in any of the ways you mentioned, it shouldn't really change in taste and mineral composition if I reseal it and it doesn't get contaminated or the bottle's material is of questionable quality and emits substances into the water?
This confuses me as I've read online that the water in supermarket bottles starts tasting bad after a few days or a week maximum even if you put the cap back on after opening them. Is this just wrong? I've personally never noticed it, but I normally don't have open water bottles around for that long.

Pressino

#8: Post by Pressino »

Most supermarket bottles are made of some sort of plastic rather than glass. A clean glass bottle should not impart any "taste" or anything else to water stored in it.

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homeburrero
Team HB

#9: Post by homeburrero »

Jh10000 wrote:If I understand correctly, that means that if the container in question is a bottle or jug of standard mineral water which I didn't modify in any of the ways you mentioned, it shouldn't really change in taste and mineral composition if I reseal it and it doesn't get contaminated or the bottle's material is of questionable quality and emits substances into the water?
Yes, especially if you are talking about using it to brew coffee.

Jh10000 wrote:This confuses me as I've read online that the water in supermarket bottles starts tasting bad after a few days or a week maximum even if you put the cap back on after opening them. Is this just wrong? I've personally never noticed it, but I normally don't have open water bottles around for that long.
You see a huge variety of advice online, much of it nonsense in my opinion. The advice from a Nestle/Purelife FAQ seems reasonable to me if perhaps a little conservative:
https://www.purelifewater.com/us/en-us/frequently-asked-questions/ wrote:Do I need to refrigerate the product after opening?

Individually sized water bottles should be consumed as soon as possible. This is to ensure optimum freshness and quality. Once opened, containers can be stored for up to two weeks in the refrigerator. For larger bottles, like our 1 gal bottles, the water should be poured into a separate container for consumption. It should not be consumed directly from the bottle itself. This is to help ensure optimum freshness and quality.
Note that they say two weeks of open bottle in the fridge even if you're taking sips from that bottle. They say "freshness and quality" but we know that nothing in water goes stale, and this is likely all about avoiding microbe contamination.

The other online advice you mentioned, to use a bottle within a few days of opening, would make sense for waters that have some natural or artificial carbonation to brighten up the taste. Carbonation does affect taste, and after the bottle is opened it will dissipate making the water taste more flat. If you are using the water to brew coffee, that carbonation is gone once you heat the water anyway, so is not an issue.
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

Jh10000 (original poster)

#10: Post by Jh10000 (original poster) »

Thanks a lot!

I presume the entirety of this will also apply to fine teas? I drink a lot of delicate Japanese teas where the water is of even greater importance than for espresso and coffee, but if nothing in the water noticeably changes that shouldn't matter.

I take it that my approach of pouring the canister content into several 1L glass bottles after opening and leaving them in a cool basement would be the best option for storage?
On this note, would it make a real difference that the bottles are not stored in a refrigerator, but in a basement?