deionised \ demineralised water

cyburger

Anyone one where I can get some for the watercoolings? is the stuff you'd get in a garage good enough?

Serephucus

Most chemists will do it, I dunno about stuff from a garage. If it says distilled, it's good enough. Water is either distilled or it's not; there's no grey area, just get whatever's cheap.

grumpymunster

There is a world of difference between deionised water and distilled water. Generally DI water is "cleaner" depending upon any contaminents in the water in the first place. If you only want distilled water and you have a condenser tumble dryer the water generated is distilled so just pop it through a filter and away you go. If you need DI get it there is a difference.

Serephucus

Ok, that's wrong. Distilled water is the purer, not deionised.

Distilled water is literally just water. Two parts Hydrogen, one part Oxygen, and nothing else.

Deionised water has had only the potentially reaction-interfering ions removed, but it will still contain contaminants in suspension.


With respect to watercooling, if you can, go for distilled, but if you really can't find it deionised water won't hurt anything, so long as you replace it with distilled when you get a chance.

I get a 5L bottle of distilled from my local chemist for €6.25. Tesco (Extra) apparently also does a 5L bottle for around €3, though I haven't had any luck finding it.

grumpymunster

Fully deionised water has a resistivity of >10MΩ with good DI circa 18MΩ this is contamination in the ppb region and is the limit of detection. Anyone who knows anything about water treatment will understand that water is always filtered prior to deionisation as damage could be done to resins employed other wise so there should never be suspended solidas in DI water. Of course any suspended solids present in DI water would negatively impact on its conductivity / resitivity so would not qualify as DI water.
Distilled water on the otherhand cannot reach resitivity / conductivity figures achived by deionisation as anything present in the water with a boiling point of less than 100C will be carried over. There is also fractional distillation of other ions which will be carried over but in smaller amounts. Distilled water is anything but pure hydrogen and oxygen.

So do you still think this is just wrong?

cyburger

Serephucus wrote: »

Ok, that's wrong. Distilled water is the purer, not deionised.

Distilled water is literally just water. Two parts Hydrogen, one part Oxygen, and nothing else.

Deionised water has had only the potentially reaction-interfering ions removed, but it will still contain contaminants in suspension.


With respect to watercooling, if you can, go for distilled, but if you really can't find it deionised water won't hurt anything, so long as you replace it with distilled when you get a chance.

I get a 5L bottle of distilled from my local chemist for €6.25. Tesco (Extra) apparently also does a 5L bottle for around €3, though I haven't had any luck finding it.

I thought deioinsed water was the requirement for water cooling as distilled didn't have the same resistance (pretty much what grumpymunster said)?

Serephucus

cyburger wrote: »

I thought deioinsed water was the requirement for water cooling as distilled didn't have the same resistance (pretty much what grumpymunster said)?

No. Deionised water will corrode waterblocks.

@ grumpy, you just proved my point. The idea is to have water that is less conductive, so distilled is better.

grumpymunster

Serephucus wrote: »

No. Deionised water will corrode waterblocks.

@ grumpy, you just proved my point. The idea is to have water that is less conductive, so distilled is better.

Do you have any idea what the figures I quoted actually are?

Pure water is measured generally in resistivity i.e. how resistive to current flow is the water. You need to understand resistivity is the inverse of conductivity. So following from that a high resistivity is a low conductivity therefore moving from ordinary DI water at say 10megs resistivity to good at 18megs resistivity means the water is significantly purer and has a significantly lower conductivity. So let’s elaborate;

DI water ordinary

Resistivity 10MΩ conductivity 0.1µS/cm

DI water good

Resistivity 18MΩ conductivity 0.056µS/cm

Distilled water (general)

Resistivity 0.1MΩ conductivity 10µS/cm

So you can see distilled water is significantly more conductive than DI. Now do you understand the difference between conductivity and resistivity?

From a microelectronics aspect distilled water is actually dirty with every microelectronics plant I have been involved in having a specification of 18megs. If anyone were to suggest at a meeting using distilled rather than DI water they would be laughed out of the room before being handed their cards.

Oh and by the way I am responsible for a plant generating some 30m3 of water a day for the microelectronics industry.

Serephucus

I know what resistivity is. Nowhere in your first post did you give figures for distilled water, only deionised. I will admit that I did not know the resistivity of distilled when compared to dionised. If the figures you quoted are true, then I stand corrected.

The main reason distilled water is used in WC setups is because of the absence of free radicals. Low resistivity will only help for a few seconds if there is a leak - which very few users will notice.

cyburger

Serephucus wrote: »

No. Deionised water will corrode waterblocks.

So if i used deionised water with a corrosion inhibitor (and anti bacterial of some kind) I'd be okay?

grumpymunster

Serephucus wrote: »

I know what resistivity is. Nowhere in your first post did you give figures for distilled water, only deionised. I will admit that I did not know the resistivity of distilled when compared to dionised. If the figures you quoted are true, then I stand corrected.

The main reason distilled water is used in WC setups is because of the absence of free radicals. Low resistivity will only help for a few seconds if there is a leak - which very few users will notice.

You may well be right regarding your WC set up. I am a chemical engineer with a very basic electronic knowledge so I am not qualified to comment. The only thing I would note is that if DI is specified there is a difference between it and distilled in the event of any warrenty issues. That is the only point I want to get across.

Serephucus

grumpymunster wrote: »

You may well be right regarding your WC set up. I am a chemical engineer with a very basic electronic knowledge so I am not qualified to comment. The only thing I would note is that if DI is specified there is a difference between it and distilled in the event of any warrenty issues. That is the only point I want to get across.

Point taken. Usually manufacturers will specify distilled, AFAIK.

@cyburger: Yes, if you use deionised with PT Nuke and a silver coil, you'll be ok for a month or so, but I wouldn't leave it any longer than that.

My basic point: You want distilled, but with the right precautions, disonised with do as a stop-gap.

jonnie45

I see a lot of confusion on forums regards the differences between distilled water, de-ionised water and so on -why do people dont read wikipedia first?

Some "helpful" people spread falsehoods like saying that boiled water is the same as distilled water, also comments about dehumidifiers and tumble driers being used as sources of distilled water.

All these discussion are basically about water purity but how pure and what the impurities are will matter in different ways to different people so you need to understand not only someone elses level of knowledge and competence but also their application before you take advice that X can be substituted for Y.

Distilled Water: Commercially produced distilled water is likely to be very pure but do not make the mistake of believing that distillation produces purity period. Reflect for a moment that when we distill alcoholic drinks then a mixture of alcohol and water not to mention chemicals responsible for taste make it across. In general if you boil water with volatile substances in it then some of those substances will make it across - see techniques like fractional distillation. For this very reason I would be wary of claims that tumble drier distillate is pure since manufacturers of soap and laundry products include all kinds of of aroma and softeners that may very well be volatile - I dont know, you would need to do lab tests but if you do require water that has no such traces then be warned further investigation may be necessary.

De-ionised water: Chemicals such as metal salts ( Table salt = Sodium Chloride, Blue Stone = Copper Sulphate ) ionise in water, that is the chemical diss-associates so that a metal +ION is no longer strongly bound to its Sulphate (or Chloride) -ION - when they move apart they acquire opposite charges hence the term ION and the signs + or -. Filters can be used to pull these charged particles out of the water and into a special resin. ORGANIC chemicals that are placed in water do not produce charged IONS and so the filtration methods do not work for these chemicals. De-ionised water is less costly to produce than distilled water (uses less energy) and so is favoured for car batteries where the principal issue is foreign IONS interfering with the chemistry going on inside the battery, the battery will be far less sensitive to small traces of ORGANIC compounds, bacteria for instance would not be able to survive the acidic environment.

Rainwater in a pure atmosphere with no contaminants should be very pure, however in polluted areas, areas subject to forest fires or volcanic ash then particulates may be present in the atmosphere and if they contain soluble minerals then its likely that raindrops forming around such particles will contain dissolved substances. On the other hand we all breathe air so the health alarmists ( the new fad for drinking distilled water ) might reflect on that and conclude that possibly drinking filtered rainwater is no worse than simply breathing - seems to be a lot of unsupported internet chaff on that subject. It takes a hell of a lot of energy to distill one cup of water and hence a lot of CO2 production - interesting that some of the main proponents of the home water distiller machines (for drinking water for heavens sake!) are on Green-Eco websites and all for a rather unproven concept.

Boiled Water: So many forum postings claim that boiled water is the same as distilled water. This is absolute rubbish. Boiled water will tend to contain dead bacteria instead of live bacteria and any very volatile impurities may have been driven off but inorganic salts will remain - a small amount of scale may deposit in the pan but really this claim is nonsense.

At the end of the day commercially produced "pure" water is likely to be only as pure as the end customer requires because it costs time energy and money to refine any chemical to a very high purity. That is why lab grade chemicals cost more than farm grade chemicals and why its better to find out for yourself if you are able rather than rely on advice from people who have a different application in mind.

jonnie45

@GrumpyMunster: Out of interest do you know what the impurities are in the DI / Distilled which are responsible for those readings - interesting that you classify distilled as being dirty what are the impurities that lead you to say this - it would be interesting to know more? Is there a point where purity demands you simply burn pure hydrogen in pure oxygen? as far as I know cryogenic "fractional distillation" ( to bodge a term) does produce a high degree of purity.

I think it is nonsense to classify any commercial "pure" water as being purer than another because in most cases the process targets the undesired impurities, "purity" is taken in context, organic impurities may not matter one iota in one application and matter a great deal in another. The electroplating industry is a good example - salts of some particular unwanted metals have to be removed often at great expense whereas many organic impurities have no consequence, soluble organic impurities may not clog up a steam iron whereas calcium carbonate will.

Conductivity tests are good if you are interested in those impurities that increase conductivity but will not serve you if you are interested in those impurities that do not affect conductivity to a marked degree.

There are different "pure" waters for different applications with different methods of measuring what we mean by "pure" in that context - it all costs money so few are interested in making ultra pure water for the hell of it - its all about what works for what application.

If someone struggles with this then really they need to look on their appliance and feed it what the manufacturer specifies.

jonnie45

Serephucus wrote: »

Ok, that's wrong. Distilled water is the purer, not deionised.

Distilled water is literally just water. Two parts Hydrogen, one part Oxygen, and nothing else.

Deionised water has had only the potentially reaction-interfering ions removed, but it will still contain contaminants in suspension.

Whooahhh there - brave to make comments like "nothing else"!!!!!

If the source water had volatile impurities they may well get carried across - see other comments and reflect on how whiskey is made, what you say is true to an extent in a kind of practical way** but it is way off the mark from a scientific point of view. Another fly in the ointment regards blind faith in the distillation process for purity is that double and even triple distillation are often deployed in different applications - a perfect process would not require repeats would it ?

Liquids still have a non-zero vapor pressure at temperatures lower than boiling point, water condenses out of ordinary air when exposed to a cold pane of glass - you do not need to boil to make water vapor. The selectivity imposed by distillation acts preferentially but not in any absolute way because the vapor pressures of all liquids is non-zero at the required temperature.

When we distill we try and tip the odds in favour of the target liquid compound by targeting a temperature at which that particular liquids vapor pressure equals atmospheric, that way it will be producing a lot more vapor than any other liquid in the mix but that is not to say that other vapors will not be present and will not go through the condensing process and out the other side. If this were not the case we would start making whiskey by placing pure ethanol into oak barrels but we do not - whiskey is defined by the "impurities" that make it across the distillation process.

Distillation merely tips the odds heavily in favour of one of the desired volatiles and is a process that can be repeated to accumulate the desired bias or rather the outcome of that bias.

** Kind of true in a practical way because one assumes that manufacturers of distilled water try and ensure there are few volatiles in the source water in the first place hence their starting point unlikely to be a mash intended for whiskey.

Ant695

Why are you replying to 4 year old comments?

levitronix

UPW is the only water thats pure , just H20, very expensive to make

distilled still has lots of impurities and d ionized has lot of impurities , cheap to make

game4it70

Wow that's a serious wall of text replying to a 4 year old thread :P

Skerries

let it go. it's just water under the northbridge

jonnie45

Ant695 wrote: »

Why are you replying to 4 year old comments?

1. Because mis-information does not improve with age
2. Even closed threads are visited by people with questions and armed with search engines.

Sum Ting Wong

jonnie45 wrote: »

1. Because mis-information does not improve with age
2. Even closed threads are visited by people with questions and armed with search engines.

Exactly and thank you for doing so Jonnie.

I came upon this thread while researching if I ought to use some purer form of water to fill my new underfloor heating system and geothermal collector as I live in a very "Hard" water (limestone) area.

I wonder if my local water impurities would have a negative impact on the many valves and heat exchanger over the long term?

Any thoughts appreciated.

grindle

Sum Ting Wong wrote: »

I wonder if my local water impurities would have a negative impact on the many valves and heat exchanger over the long term?

If it's anything like the water in Clonmel your pipes would be destroyed in a year or two.

Mech1

I make RODI water at home if its any use to you guys, TDS reading of zero, its used as the basis of a salt water mix for my marine fish tank.

https://en.wikipedia.org/wiki/Reverse_osmosis

available anytime if you need some.