Distilled Water

[Mother]

I make my distilled water from a distiller which uses steam to make the water.I have always known that the water, when tested was slightly acidic.One of the teachers has just told me this also.As if I didn't know!!!! Anyway this leads me to ask all of you if your water is also slightly acidic???? I can now see everyone rushing to test their water (distilled that is!!)
Apparently the reason for the slight acidity of the water is because of the hydrogen bonding sometimes one of the hydrogen protons from one water molecule "jumps"!!! causing the acidity.
Wonder if this can be corrected?? Or is it really not significant enough to worry about??
Got you all thinking??
Cheers
Mother

[Ian]

I spent a lot of time last year on "Distilled Water" as our distiller was rapidly emptying Warragamba dam to condense only a few litres of water. We tried shop bought Distilled Water, and Shop bought deionised water, and eventually bought a very efficient filter system from Serrata. In every case, the water was acidic, sometimes down to pH 5.5 or so!!
When I enquired as t why, I was told that the water absorbed CO₂ from the air making dilute Carbonic Acid.
We recently got a pH metre for out Data Logger (actually got a new Data Logger with a pH meter) and I note that the instructions say NOT to use distilled water to callibrate it as Distilled Water is normally slightly Acidic. Rather they recommend a Buffer sol'n be used.
I am not sure what the solution is (excuse the pun). I am sure Robb would know.
I hope that helps.

regards
Ian

[Xenon]

CO₂ from the air reacts with 2 water molecules forming bicarbonate : HCO₃ plus hydronium ion : H₃O
Its the increased hydronium ion concentration that causes lower pH.
We use a Millipore filter; no wasted water and I just checked it with UI, it was ph 7.
Stills are water bandits and those bench-top stills are the worst - so inefficient..

[Robb]

Hi All,

Xe, (David) has it right on the money here, but there is one thing he forgot to mention which I will add to complement his answer... when the Bicarbonate and Hydronium Ions become free radicals in solution this phenomenon is actually reversible. It is this reversing in which produces the "Real Change in pH". Not the absorption of CO₂ as most people may think (although they are almost correct)...

Well done Xe, Mother, and Ian for having a good stab at this question....

Cheers,


Robb.....

[RosalieM]

What is a millipore filter and where do you get one? I have been looking into filters in case we can fit one in the budget as we stopped using our still because of water restrictions and started buying the bottled distilled water. If this one wastes nothing it might be worth looking into.
Rosalie

[Robb]

Hi Rosalie,

The Millipore filter is a fine filter paper with fine holes within it these holes are usually around 0.45 microns in size. Much, much smaller than the conventional filter paper...

You can also get the filtration apparatus with it as well. Due to thin Millipore filter paper the equipment allows you to put together the filtration apparatus using the filter paper. And when you have finished the filtering then you simply disassemble the apparatus and allow it to dry, ready for the next use.

Usually the Millipore apparatus is glass and can be expensive if you drop them...

Cheers,

Robb.....

[smiley]

I buy de-ionised water from a car battery manufacturer/distributor. His water has to meet various "ppm" industry standards, so its pretty clean. Its also better than pouring thousands of litres of water down the drain to distill just a few, even if I do live where water in not in shortage. We pay 50c/litre so it's way cheaper than the stuff you buy in shops and, according to the dude at the battery shop, the store bought stuff doesn't meet industry standards etc etc!

Cheers, K

[labman]

Very interesting,
I am begrudgingly using a bench top still, but am interested in alternatives that are more water efficient, and the replacement filters don't cost a fortune. Do those Millipore filters fall into this category.If so, like Rosalie,I would like to know where to purchase them, and a rough idea of the cost. Thanks in advance.
Cheers,
Lisa

[Ian]

We pensioned off the old still last year and bought a twin filter "VERTEX" benchtop filter from Serrata for $685. It produces 1L per minute and seems to satisft all my tests. It claims to produce "BS Grade 2 water" (whatever that means!) and when I have tested it with our StreamWatch kit, it seems comparable to bottled distilled water in terms of TDS, conductivity, pH, chlorides, etc. I recken it is as good as distilled water and my Chem teacher has not complained

Replacement filters are $64 for the Activated Carbon Filter and $85 for the Mixed Bed Resin Filter. It has one of each, and it has a little red light that tells you when the filters need replacing! (although my little red light has not complained to me yet!)

I hope this helps

Ian

[fibreweb]

Earlier this year due to water restrictions and the fact our old still ( about 15 years old) took about 20 litres to make 1 litre of distilled water we pensioned him off and purchased a Calligan deioniser from Scientrific, the same model can be purchased from Haines, for about $650. As we have only had it a couple of months I have no idea how long the cartridges will last, as it depends on your water quality.

Upon testing for pH it is between 6.5 and 7.5 depending on the day which the teachers are quite happy with.

Wendy