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

[superheat6k]

The dehumidifier I installed a couple of months ago is producing ~1/2 litre of water per day into the galley sink and over the side.

Now it has thoroughly flushed itself through is the water pure enough to use in my batteries ?

As an aside the ~ 130w power consumption plus the latest heat from the water produced is nicely adding a background warmth to an otherwise cold cabin, and is keeping the cabin temperature above freezing even on the coldest days. The that was forming previously mould has now all gone.

 

[rogerthebodger]

The output from a dehumidifier is in fact a condensate so is close to distilled but could pick up impurities in the process.

The battery top up water is specified as deionized water but my chenistory is not good enough to determine is deionized and distilled the same

VicS would know for sure

 

[CrikeyChris]

I once made tea using water from my Meaco DD8L (dessicant) and it was undrinkable. A compressor type dehumidifier (as Roger points out) is probably producing pure water.

 

[RivalRedwing]

Personally I wouldn't, genuine battery water isn't exactly a fortune to buy @ £3 for 5L.
Distilled is just that - condensate from a distillation process; de-ionised comes in various types from ion exchange or reverse osmosis grade DI water (broadly the same a distilled) to much higher purity 18.2Mohm grade DI water which is passed through additional ion exchange- and related filters to better remove impurities (It tastes disgusting by the way).

 

[ylop]

The output from a dehumidifier is in fact a condensate so is close to distilled but could pick up impurities in the process.

it will almost certainly pick up co2 from the air and form carbonic acid unless you capture it in a way that is not open to the air. It will have whatever fluff, dust, mould spores, paint fumes etc that are blowing round the cabin, quickly mixed in with it too - and potentially metal ions from any pipe work or surfaces it comes into contact with between condenser and bottle. Probably fine for a battery… but killing a battery is an expensive way to save a couple of quid on the right stuff.

The battery top up water is specified as deionized water but my chenistory is not good enough to determine is deionized and distilled the same

Deionized and distilled are not the same although for some purposes the product is interchangeable. Lab distilled water is often double distilled. Deionized water passes through either resin or reverse osmosis or both depending how pure you want it.

 

[superheat6k]

Thanks

I'll continue to let it drain away.

 

[thinwater]

I tested water from a number of sources, including dehumidifiers, rain, Ac units, and tap. I compared them to ASTM and battery maker specs.

Obviously RO and DI water is good, but carefully collected rainwater and dehumidifier water met the specs (< 20 ppm TDS). AC water (70-85 ppm) and tap do not. Mostly, I use water from a home RO (<10 ppm), but don't use water from a seawater RO (no seawater RO can come close to meeting the chloride limit).

It's not always about the money. I've run out of water in remote areas where bottled distilled water wasn't an option.

		Battery Water Specifications		Engine Coolant Water Specifications	Tap Water
					(typical range)
	Trogan Batteries	Exide Batteries	ZVEI (German Electrical Trade Association)	ASTM D3306
Contaminant		ppm unless otherwise stated		ppm unless otherwise stated
Color	Clear and White	Clear and White	Clear and White		Clear
Conductivity	158 uS/cm **	158 uS/cm **	30 uS/cm	79 uS/cm	100-1000
pH			5-7	5.5 - 8.5	6-8.5
Suspended Matter	Trace	Trace			0-5
Total Dissolved Solids	100	100	18 **	50***	60-600
Organic and Volatile Matter	50	50	20		2-25
Ammonia	8	5	40
Antimony	5		0.1
Arsenic	0.5		0.1
Bismuth			0.1
Calcium	40	20 *	0.1	9 *	25-300
Cadmium			0.1
Chloride	5	5	0.5	25	10-200
Cobalt			0.1
Copper	5		0.1		0-0.5
Chromium			0.1
Iron	3	4	0.1	1	0-0.3
Lead			0		0
Magnesium	40	5 *	0.1	3 *	5-150
Nickel	None Allowed		0.1
Nitrate	10	10	2		0-5
Nitrite	5	5
Platinum	None Allowed				0-0.2
Selenium	2		0.1
Sulfate				50	20-250
Tin			0.1
Zinc	4				0-2

 

[wonkywinch]

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.

 

[thinwater]

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 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.

 

[B27]

The frost from the deep freeze at home is probably a lot cleaner?

I have a dehumidifier in my workshop, it collects fine dust and probably a bit of mould because it cycles on and off, so sometimes it's probably warm and damp?
D-water is very cheap in some shops

 

[wonkywinch]

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.

The boat's not had much use so I'm guessing it's dust in the air that's passing the filter. Or, as it's brown, a rusty heat exchanger.

I see the UK based maker has a sale on and they are £200 at the moment using code FEB33. You can add a 5 year warranty for £45 which might be worthwhile for use in a more hostile environment.

2650e Dehumidifier | White Portable Home Dehumidifier

 

[Boater Sam]

How about defrost water from a freezer? I have used it for ever to top up batteries.

 

[thinwater]

How about defrost water from a freezer? I have used it for ever to top up batteries.

I tested that several times. It did not pass, about like AC condensate (40-60 ppm TSS). Better than tap, but not as good as I might have expected.

 

[vyv_cox]

I tested that several times. It did not pass, about like AC condensate (40-60 ppm TSS). Better than tap, but not as good as I might have expected.

Depends on your tap water composition. Our very soft water in Wales contained very little in the way of salts. I know of several knowledgeable people who topped up batteries with it.

 

[JayDomK]

I once made tea using water from my Meaco DD8L (dessicant) and it was undrinkable. A compressor type dehumidifier (as Roger points out) is probably producing pure water.

I assume this device is not designed to produce potable water. I wouldn't risk drinking from it. Unless I wanted a thrill.

 

[JayDomK]

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.

It is probably the air itself that is different. If the air is more or less clean, the result will be more or less clean. Provided the parts of the device are clean.

 

[AntarcticPilot]

I assume this device is not designed to produce potable water. I wouldn't risk drinking from it. Unless I wanted a thrill.

+1 Most desiccants are hygroscopic substances that dissolve in water absorbed from the air. Salt does it to a small degree - that's why it gets damp and clumps up on board (yes, you can put a few grains of rice in with it!) So the liquid resulting from the use of a desiccant is a concentrated solution of whatever they used - I'd imagine Calcium Chloride is a major component. They usually put a dye in the desiccant material so the resulting solution is brightly coloured to warn you NOT to drink it !

 

[Momac]

+1 Most desiccants are hygroscopic substances that dissolve in water absorbed from the air. Salt does it to a small degree - that's why it gets damp and clumps up on board (yes, you can put a few grains of rice in with it!) So the liquid resulting from the use of a desiccant is a concentrated solution of whatever they used - I'd imagine Calcium Chloride is a major component. They usually put a dye in the desiccant material so the resulting solution is brightly coloured to warn you NOT to drink it !

The water from my Meaco DD8L is crystal clear . (I wouldn't attempt to drink it and I don't have any batteries that need topping up).
I understand the desiccant in the Meaco is is Zeolite.
I could easily collect the water produced to mix with engine coolant. Would this be better than using tap water?

 

[thinwater]

Depends on your tap water composition. Our very soft water in Wales contained very little in the way of salts. I know of several knowledgeable people who topped up batteries with it.

You really need to test it. If it is city water, you can probably look it up on-line. Yes, it absolutely could be good enough. Or not.

I operated an antifreeze production (we manufactured ethylene glycol) and formulation plant (additives) on a property with three wells. The first was about 20 ppm hardness. We could make coolant with that. Business grew and we drilled another 700 feet away, and the harness was 500 ppm. No good. We drill another, another 500 feet away. 1200 ppm. Crap. We shifted all the plant water needs to the 500 ppm well and used the 20 ppm well for coolant and boiler feed only. Just slight differences in the soil.

Rain can be good, but it depends on the exact location (wind and spray) and how you collect it.

 

[AntarcticPilot]

The water from my Meaco DD8L is crystal clear . (I wouldn't attempt to drink it and I don't have any batteries that need topping up).
I understand the desiccant in the Meaco is is Zeolite.
I could easily collect the water produced to mix with engine coolant. Would this be better than using tap water?

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.