Distilled water alert

[Earl Dunbar]

Deja vu all over again.

(there was a url link here which no longer exists)

In my biased opinion, DW - real or RO - is so cheap in America I don't know why anyone wouldn't pay $1/gal for it for mixing developers and Photo-flo. Just cautionary, especially in areas of hard water.

Using condensates is probably worse than using typical tap water. Whether A/C, dehumidifier, or the dryer type Autumn speaks of (never heard of such a thing) the air is loaded with dust and pollen. The resulting water is anything but pure.

I use the water from my dehumidifier. I first filter it through a Brita filter, then through a Melita filter in a Melita funnel. I'm not sure of what the Brita might add to the water, but if anything I don't think it's significant. The 2nd filtration makes sure I don't have any major particulate matter in the water.

I mix ALL my solutions using this water, and use it for wash using the Ilford method. It allows me to use PhotoFlo 1:400, which works better for me than 1:200, by far. If I am very careful, I have gotten spotless negatives without the PhotoFlo, just rinse with the dehumidifier/deionized water.

I can't speak for any issues regarding fungus, etc., but so far so good. And my optometrist forbade me from using distilled water to rinse contact lenses because she said there ARE bacteria that are not killed in the distillation process, whatever that entails by the various "distillers".

My last batch of TMX, using DI/dehumidifier water were sparkling. Not perfectly exposed, mind you, but well-processed.

I only use distilled products for recreational imbibing, especially those from the Highlands and surrounding area ... great after a darkroom session to either celebrate or drown the sorrows.

 

[KD5NRH]

Basic chemistry tells you that distillation will distill anything which vapourises at or below the temp used.

And illiterate moonshiners can tell you how not to get the heads in the liquor. I'd expect major corporations to be able to manage that.

 

[Paul Verizzo]

I use the water from my dehumidifier. I first filter it through a Brita filter, then through a Melita filter in a Melita funnel. I'm not sure of what the Brita might add to the water, but if anything I don't think it's significant. The 2nd filtration makes sure I don't have any major particulate matter in the water.

And you saved how much money? Sorry, I'm tight, but I recognize good value, store bought DW.

 

[walter23]

Wouldn't pure acid be a solid/powder? HCL is aqueous, not a liquid.

Pure sulfuric acid is a liquid. And a fun one to try to mix with water

 

[JohnFinch]

There's lots of fungus spores in the air, lots of bacteria in wet clothes (wet clothes are extremely disgusting...drying really cleans them). Just a lot of nasty crap, which is why you're not supposed to drink dehumidifier water.

I'm not supposed to drink it? Darn...

 

[walter23]

My understanding is that water (H2O) is what is called an amphiprotic substance and that it reacts with itself. ie H2O + H2O gives H3O+(aq) and OH-

Therefore with no exposure to air or any other gas, it will ionize itself until it reaches its equilibrium at some point. And that means that pure H2O is unstable and even if you can get it to be pure 100% H2O it won't stay like that. And that hydrogen ionization is what determines the PH so the PH changes all by itself until it reaches equilibrium.

Yes but it will change its PH from that obtained in pure H2O. And it will also change its electrical conductivity which also, I think, means it will change its reaction properties to other chemicals. I'm just making the point again, that pure 100% H2O is only to be found in the most stringently controlled lab conditions and its life is very short. Meaning, what people think distillation does for water is usually very wrong.

As pointed out in another part of this thread, the equilibrium concentration of ions in pure water is what gives it a pH of 7 (with some temperature sensitivity). The dissociation you speak of is what gives water it's neutral pH. Because pH is the negative log() of the concentration of hydronium ions, pH is undefined for a concentration of 0 (log(0) = infinity). In other words, what you say about "pure water" without H+/OH- being too transient to observe is true (maybe in ice?), but this is already accounted for in the definition of pH. The amount of dissociation you get is not random; it's dependent on environmental conditions and solutes in the water, and for pure water at standard conditions, pH = 7 is the consequence.

 

[Anscojohn]

Darn-it all!! Here I've been saving my AC run off water during our humid D.C. summers all these years and have been asking for TROUBLE!!. Gosh, and all I do is filter it through a coffee filter to get the slugs and bugs out. And my D-23 and DK-25R lasts for months and months and months. And my Rodinal is always consistent. And my negs always clean; and......(VBG)

 

[walter23]

the needs of 99% of home darkroom workers are met by distilled water from the grocery store, and if there is some concern about its quality, the thing to test is conductivity, not pH.

I'd say our needs are probably met by tap water. I live in a hard water area, and I just use some wetting agent when I dry my film. No problems. Maybe if you were making emulsions and coating your own films you'd have to worry about extreme purity, but for process/stop/fix and most zone system stuff I suspect the impurities will have little effect. Maybe it would matter if you'd calibrated your darkroom and then moved to another area with different water qualities, but I'm not sure. Intuitively I'd suspect the effects would be minor; the stuff in your developer should overwhelm any impurities in your relatively pure tap water.

 

[AutumnJazz]

Alex and PE,
Basic chemistry tells you that distillation will distill anything which vapourises at or below the temp used. Therefore basic chemistry tells you that distillation will not purify water 100% if there is anything in it which does vaporise at or below the being used. What the PH scale is, is irrelevant in understanding that. You have said in your own answer that distillation won't drive everything out of water. So it would seem you are contradicting yourself.

So once again, why do assume that distillation will make 100% pure water which you then test by looking at its PH?

The results everyone are quoting show its not PH7 but still you persist in the assumption that it should be. Sounds very much like a very basic misunderstanding of chemistry to me.

To get pure water via distillation, don't you simply not capture/condense anything that vaporizes under 100C?

 

[Photo Engineer]

To get pure water via distillation, don't you simply not capture/condense anything that vaporizes under 100C?

Basically, yes, but some chemicals bond so tightly that they come over with water. This is called steam distillation in some cases, and you can actually purify some of these chemicals by steam distillation from water.

For this reason, it is often impossible (depending on source) to remove water and benzene from ethyl alcohol, and you end up with a 95% mixture of Ethanol with either water, or water + benzene. Even the 99% ethanol has some degree of impurity for this same reason.

Invert this and you can have ethanol in water after distillation.

Thats what started me off.

PE

 

[Murray Kelly]

Just tested the tap water - 6.9. Had a lot of rain lately. Before that it was something like pH8 or 9!
Probably tiny amounts of contaminants. How real would the threat be to home brew developer when there is so much chemical to drown out this pH shift?
Murray

 

[dancqu]

How real would the threat be to home brew developer when
there is so much chemical to drown out this pH shift?

So much chemical to drown out is about it. Not to worry.
Good for consumption but could be long on spot and/or
precipitate producing calcium etc. Dan

 

[AutumnJazz]

As someone who loves chemistry, the thought of making a solution with anything besides distilled water and a volumetric flask makes me shudder.

Yes, I probably have OCD.

 

[gainer]

Kirk;

Yes, I read to the end. Yes, I believe your figures and understand the ionic strength.

My point is that pH is not reliable for a measure of DW purity, just an indication of purity. Other methods should be used to test. But, also, some DW is not DW but merely "purified" by some means such as RO.

Rob has explained it well in post #36 in plain English and you have given the technical detials. Also, I do remember getting values of about 6.0 - 6.5 for DW many years ago.

PE

I agree that pH is not a proper way to determine impurities in water. Let us place 2 unidentified containers containing liquid side by side. Each liquid measures pH at exactly 7. Is there a law of nature or chemical science that that means they are both pure water? Certainly not. One could mix, for example, sodium ascorbate and ascorbic acid in such proportiones that the resulting solution would be 7. You would need some other test to determine whether either or neither or both could be used to mix any photographic solution. Taste might be a better test, especially if you can get someone you don't care for to taste it for you.

We could use sufficiently filtered chicken soup to mix some of our solutions. I have seen no harmful effects of using dehumidifier condensate or rain water, but I do not use my well water for solutions containing carbonates because I know it comes from limestone deposits. Where possible I use non-carbonate alkalis as activators. There are some processes that would be spoiled by the iron and sulfur in some of my neighbors' wells that are not in my water. If you think city or well water is not good enough for your chemistry, you can do as I did and have it analysed. I did it so as to have a record of my drinking water in case the drilling of a nearby oil well changed my well water. You might find it worth the cost of the analysis.

 

[dr5chrome]

..it would be terribly against the law to sell Distilled water as Di water.
Di water will kill or make you very ill if you drink it [im talking many glasses a day]. Distilled water can only be made '1' way, by boiling the water.

PE; i have never seen distilled water have a PH different from 7.0 and alway '0' PPM. Steam distillation is pure water [thats if you're not distilling some chem.agent]. The only way acid or anything else could be in there is if the container or tubes has something in them [er: PPM meter].

Folks; the best option is to make your own distilled water. you can pick up a small distiller on ebay for under $80. it will pay for itself in 10 uses!

dw

Yes but some "Distilled water" has never seen a still, often de-ionised water is sold as Distilled water, and it isn't checked or tested properly either.

Good high grade Distilled water for lab use is usually double distilled or de-ionised and then distilled. But many small companies just de-ionise water & sell it as "Distilled" for use in irons & batteries for domestic/garage use, and to be fair it's probably fit for that purpose only.

Ian

 

[AutumnJazz]

Di? De-ionised? Why would it kill you?

Or do you mean heavy water?

 

[gainer]

But you have seen solutions that were not distilled water that had pH=7.0, have you not? And if your distilled water is collected in the normal atmosphere, it will have a slightly lower pH because the standard atmosphere contains CO2...more in fact than it did 25 years ago.

 

[Photo Engineer]

But you have seen solutions that were not distilled water that had pH=7.0, have you not? And if your distilled water is collected in the normal atmosphere, it will have a slightly lower pH because the standard atmosphere contains CO2...more in fact than it did 25 years ago.

Well, this was part of my original point Patrick.

I seem to remember the pH of distilled water back in general chemistry, when we were learning about pH, to be less acidic than what I measure now. I remember pH 6.5. In fact, I remember getting this value at EK with our old analog Corning meter with the DI/DW supplied to our labs.

I know why DW should be acidic, it is basically a question of using it for a measure of purity and whether it is slightly more acidic due to the rise in CO2 and "acid rain". Oh well.

And we have seen what can be sold as DW in the comments here.

PE

 

[Paul.]

Oh bugger me, ten pages on the problems distilled water can cause in the darkroom. Bloody glad I only use tap water, not a clue what its ph is and realy don't care, it works with no problems.
Prehaps we this side of the pond are luckier or just less paranoid.

Regards Paul.

 

[Kirk Keyes]

Di? De-ionised? Why would it kill you?
Or do you mean heavy water?

He's referring to the urban legend that drinking demineralized (deionized or distilled) water will kill you "by leaching out all your minerals". Infact, some New Age "medicine" practicioners try to "purify" their bodies by drinking demineralized water in an attempt to leach out toxins. Rubbish.

Here's a link to a page from the Center from Disease Control that discussed drinking water in many aspects:
http://www.cdc.gov/nasd/docs/d000001-d000100/d000009/d000009.html
Way down on the page they say:

Mineral-free water or distilled water is treated to remove the minerals that occur naturally in water. Almost all sodium is removed by these processes. The resulting water is rather flat and tasteless for drinking because of the lack of minerals.

No dangers listed for demineralized water, unlike the dangers they discuss in other parts from other known contaminants that can be found in some drinking waters. "Flat and tasteless" is the biggest hazard from drinking it...

Granted, there is evidence that drinking waters that have some minerals like calcium can be good for you. And unless you have a diet low in minerals, which most people that have access to demineralized water do not, then there is no concern for drinking demineralized waters.

 

[gainer]

Well, this was part of my original point Patrick.

I seem to remember the pH of distilled water back in general chemistry, when we were learning about pH, to be less acidic than what I measure now. I remember pH 6.5. In fact, I remember getting this value at EK with our old analog Corning meter with the DI/DW supplied to our labs.

I know why DW should be acidic, it is basically a question of using it for a measure of purity and whether it is slightly more acidic due to the rise in CO2 and "acid rain". Oh well.

And we have seen what can be sold as DW in the comments here.

PE

I suppose you know I was sticking up for your assertion that pH doesn't tell much about what might be in your water. For example, human saliva will test about the same as distilled water collected or stored in the normal atmosphere. I haven't found the number for sea water pH in CRC Handbook, but it's mostly a solution of a strong base and a strong acid, and probably not much different ftom saliva. So, if one went by pH alone, one could use saliva or sea water to mix developers.

 

[Earl Dunbar]

So, if one went by pH alone, one could use saliva ... to mix developers.

Lord help me if I have a LOT of film to process!!

 

[Tom Hoskinson]

Ph problems with commercial DIW

Well, this was part of my original point Patrick.

I seem to remember the pH of distilled water back in general chemistry, when we were learning about pH, to be less acidic than what I measure now. I remember pH 6.5. In fact, I remember getting this value at EK with our old analog Corning meter with the DI/DW supplied to our labs.

I know why DW should be acidic, it is basically a question of using it for a measure of purity and whether it is slightly more acidic due to the rise in CO2 and "acid rain". Oh well.

And we have seen what can be sold as DW in the comments here.

PE

We periodically have had pH and electrical resistance problems in our lab with commercially supplied Deionized Water (ph 5 to 6.5) and/or resistance less than 18 megaohms (our DIW resistivity quality standard). We buy DIW with the right to test and refuse it.