One for the chemists - how pure is water from a dehumidifier

[Momac]

Clarity is not a reliable indicator of dissolved minerals. A saturated solution of salt will look just the same as drinking water, unless you do tests to measure properties like refractive index. If water has been in contact with zeolites it will almost certainly have carried some mineral content from them; zeolites are pretty reactive by mineral standards, and offer a vast surface area on which reactions can take place. The latter property is, of course, why they are efficient desiccants. But I wouldn't be at all surprised if the water had a high level of dissolved solids - as much if not more than tap water.

It might be ok - I don't know the exact mechanism of a desiccant dehumidifier - but I certainly wouldn't take the chance.

The desiccant isn't consumed so I don't expect the dissolved solids to be high
In any case if the dissolved solids are Zeolite isn't that better than the alternative of lime in tap water as far as engine coolant is concerned?

 

[AntarcticPilot]

The desiccant isn't consumed so I don't expect the dissolved solids to be high
In any case if the dissolved solids are Zeolite isn't that better than the alternative of lime in tap water as far as engine coolant is concerned?

The dissolved solids wouldn't be zeolite, it would be breakdown products of reactions between water and zeolites. Probably things like sodium silicate (waterglass!). And it would be slow. But any dissolved solid is bad for engines; you don't know where in the engine it might come out of solution.

Zeolites are hydrothermal minerals originally deposited from hot water under pressure. So exposing dessicated zeolites (they are naturally hydrated with chemically bound water) to water will certainly result in some changes; the zeolite will slowly become permanently hydrated with water bound in the crystal structure.

Incidentally, zeolites aren't a single thing; they are a large family of minerals with widely differing properties. So it will depend on exactly which zeolite they are using.

As I say, it could be ok, but why take the chance when distilled water is readily and cheaply available?

 

[thinwater]

The dissolved solids wouldn't be zeolite, it would be breakdown products of reactions between water and zeolites. Probably things like sodium silicate (waterglass!). And it would be slow. But any dissolved solid is bad for engines; you don't know where in the engine it might come out of solution.

Zeolites are hydrothermal minerals originally deposited from hot water under pressure. So exposing dessicated zeolites (they are naturally hydrated with chemically bound water) to water will certainly result in some changes; the zeolite will slowly become permanently hydrated with water bound in the crystal structure.

Incidentally, zeolites aren't a single thing; they are a large family of minerals with widely differing properties. So it will depend on exactly which zeolite they are using.

As I say, it could be ok, but why take the chance when distilled water is readily and cheaply available?

I could try and give a chemist's answer.

Or I could offer the engineer's answer; test the water. As AP listed, there are too many variables to be sure of anything. A simple test for TDS would be a first step.

 

[Neeves]

I direct our dehumidifier drain hose into a small bowl in the sink so I can check it's actually still working whenever I visit the boat.

Despite cleaning the (fairly course) air filter, the water always looks dirty brown where it's picking up impurities from the air.

The fish and oyster farm under the pontoon at Mercury can drink it.

and the customers eat the fish and oysters . ?

Jonathan

 

[Momac]

As I say, it could be ok, but why take the chance when distilled water is readily and cheaply available?

Being a bit picky but I think you mean de-ionised water.
Yes it is cheap.

 

[wonkywinch]

and the customers eat the fish and oysters . ?

Jonathan

No, they are for repopulating the Solent, not for commercial fishing. The dust in the air causing my water output to get dirty is surely going into the surface of the river on a much wider scale. I doubt it's toxic.

BLUE plans to restore oysters to the Solent | Blue Marine Foundation

 

[Refueler]

From a DeHum ... its crap - simple answer.

And just to add .. Rainwater is mild Carbonic Acid ... its what eats away at South Downs etc in southern England ... as RW falls it absorbs CO2 creating slightly acidic ... about 5 - 6 on Ph

 

[AntarcticPilot]

I could try and give a chemist's answer.

Or I could offer the engineer's answer; test the water. As AP listed, there are too many variables to be sure of anything. A simple test for TDS would be a first step.

I should, perhaps, mention that atmospheric CO2 dissolved in the water would also contribute to the chemistry.

 

[Refueler]

I should, perhaps, mention that atmospheric CO2 dissolved in the water would also contribute to the chemistry.

Conyeshna ..... dah !

 

[johnalison]

From a DeHum ... its crap - simple answer.

And just to add .. Rainwater is mild Carbonic Acid ... its what eats away at South Downs etc in southern England ... as RW falls it absorbs CO2 creating slightly acidic ... about 5 - 6 on Ph

It was in fact the erosion of the South Downs and his calculation of the rate of erosion that enabled Charles Darwin to establish a lower limit to the age of the land mass, even though this was several orders of magnitude below the actual age, as he appreciated himself.

 

[lydiamight]

I don't drink the water from our dehumidifier or use for batteries---but it is handy to use in the steam iron.

 

[oldmanofthehills]

Battery top up water needs to be free of calcium salts (ions) and similar as these will ruin battery performance.Distilling does this, as does deionising via resins. Frost condensate should be similarly free of metal salts.

Selective freezing can be used to improve purity of water, though not enough for battery top up, though it is used to remove purish water from cider to improve the alcohol strength for applejack.

However a dehumidifier output might well be contaminated by dust and other stuff one doesnt want in a battery, and as others have said buying a bottle of distilled or deionised is cheap

 

[Refueler]

It was in fact the erosion of the South Downs and his calculation of the rate of erosion that enabled Charles Darwin to establish a lower limit to the age of the land mass, even though this was several orders of magnitude below the actual age, as he appreciated himself.

Many a good walk on the Downs ..... North and South

 

[AntarcticPilot]

Conyeshna ..... dah !

Not quite - I'm thinking of the chemistry in the zeolites, not solution of carbonate rocks.

 

[thinwater]

There are two obvious ways to be sure. I'm chemical engineer, this is good discussion, but at the end of the day I would do this:

• Buy distilled water. Cheap and common.
• Test. Tapes and electronic testers are cheap, and many pet stores, for example, will do it for free.
• If you are somewhere remote and the first two options don't work for you, dehumidifier or (carefully collected) rainwater work in a pinch. At least in my testing, they passed.

But the first two are best. I always carry a few 12 ounce bottles, that I filled at home, on the boat for convenience.

 

[rotrax]

And this is why we test things. I tested several (no air filters) and the water was always crystal clear and the tanks unstained (compressor and Petlier types). Something is very different in your system.

Yes, I have extensive experience of compressor type units. All have produced crystal clear water. When drying out a large re-laid cement floor in our Motorcycle Showroom the two large commercial units produced eight gallons per day. Early on, after an overnight session, the four gallon receptacles were full to the brim. The large shop plate glass windows were also running with condensation.