Distilling water

Water starts to evaporate at below than 100 degrees centigrade.  As you raise the temperature of the water, it will evaporate faster.  If your goal is to make water more pure, do you run the risk of having contaminants also evaporate as well by raising the temperature to boiling?  I have found lots of posts in many forums on distilling water, but none that address this question.

My guess is to keep the exit/condensation pipe higher than the potential splash height of the boiling water.

Thank you.  But I am not concerned about undistilled water getting into the collection of distilled water.  My concern is that there might be some chemicals in water that also might evaporate as well, the placement of the collection tube would be irrevelant.

I have thought of this too (for water or drinking alcohol), and I guess one tactic would be to not collect any distillate until the heated water comes close to the boiling temperature of water at your altitude. Other volatile chemicals might boil off before the water starts boiling, though as you point out, some of the water will be evaporating at that point so you'd lose a little distilled water.

Another tactic is to use water that is as clean as you can manage before you start distilling it, and then just hope that the result is pretty much only water. That's what we did at our school, and our distilled water apparently tested very well, more than pure enough for batteries.

Distilled water has 0 TDS ( means total dissolved solids).
You can get TDS meter and check yourself how pure is it.
Rain water is as pure as distilled water.
Why do you need the distilled water? Its not good for human consumption because you will loose minerals.

Tom Connolly wrote:Thank you.  But I am not concerned about undistilled water getting into the collection of distilled water.  My concern is that there might be some chemicals in water that also might evaporate as well, the placement of the collection tube would be irrevelant.

It depends on what contaminant is in the water. As an example, let's call ethanol a "contaminant", and it will evaporate out of water at around 175F along with a some water vapor. Some things like minerals, dissolved in water, will not go into a vapor form in the low temps (boiling and under) and will collect and concentrate on the bottom of the vessel containing the water being distilled. I believe, that other contaminants, such as nitrates from synthetic fertilizer or poisons from crop spraying for example which may or may not be in ground water around conventional farms, may be able to stay behind in the distillation vessel if their volatilizing temperatures are known, and the water kept under that temp. Perhaps a simple solar still where the water stays cool and evaporates very slowly would help increase the odds of known and unknown contaminants staying behind in the still and not carrying over with the water vapor into the collection vessel.

Because of many years of mining - and poorly managed water use - arsenic levels in the ground water in Northern Nevada - and maybe other places - is rather high.  I am looking at ways of addressing this issue.

Tom Connolly wrote:Because of many years of mining - and poorly managed water use - arsenic levels in the ground water in Northern Nevada - and maybe other places - is rather high.  I am looking at ways of addressing this issue.

You'll be ok distilling water without arsenic carrying over into the collection vessel. Arsenic is heavier than water, and its sublimation point at which it goes from a solid metal to a gas is 1137°F. Any arsenic in the water to be distilled will be left behind in the distillation vessel.

James Freyr wrote:

Tom Connolly wrote:Because of many years of mining - and poorly managed water use - arsenic levels in the ground water in Northern Nevada - and maybe other places - is rather high.  I am looking at ways of addressing this issue.

You'll be ok distilling water without arsenic carrying over into the collection vessel. Arsenic is heavier than water, and its sublimation point at which it goes from a solid metal to a gas is 1137°F. Any arsenic in the water to be distilled will be left behind in the distillation vessel.

Thank you! At the risk of hijacking my own thread, what are the other options for removing arsenic?  I have seen some rather inexpensive solar stills for water that do distillation - inexpensive but large - that are easy to maintain.  One option I was thinking of was to distill part of the water - enough to remove some of the arsenic.  I am aware of the benefits of the TDS in water...must make wise choices here.  My idea is to start out with some simple mechanical filtration - probably activated charcoal or even a fabric prefilter.  Some kind of settling pond or tank might be in order if there is a lot of silt or solid particulate in the water.  I am not sure what to do beyond that.  Right now I am going off of data collected from neighbors and the water district, which should be pretty similar to what I will find.

Tom Connolly wrote:... what are the other options for removing arsenic?  

Reverse osmosis filters will remove arsenic, and everything else too, and unrefined sea salt is one good way to add minerals back to the water.

James Freyr wrote:

Tom Connolly wrote:... what are the other options for removing arsenic?  

Reverse osmosis filters will remove arsenic, and everything else too, and unrefined sea salt is one good way to add minerals back to the water.

Thanks!  That is one option.  It does "waste" water, but the wasted water could be diverted to water flowering plants and shrubs.

Tom Connolly wrote:

Thanks!  That is one option.  It does "waste" water, but the wasted water could be diverted to water flowering plants and shrubs.

Indeed, the waste water could be diverted to water flowering plants and shrubs, but I think it is important to consider the contaminants in the waste water and depositing them into the soil, especially if used around plants to be eaten, and what contaminants could end up in the plant tissues and fruits.

At the risk of being unpopular it should be mention excessive drinking of distilled water is bad for you, water intoxication. See water intoxication for more detailed info. Basically though it strips the minerals out of your body and makes you drunk then dead. distilled water is more likely to make you sick, than pure H2O. But one should know that it is dangerous

This can easily be stopped by adding some minerals to your water. Safe ones of course. You don't have to do a lot, the big problem is having no to little mineral content. Water wants to be full and will take what it needs from where ever it finds minerals, be that your body or other options. That is why professional water sellers add minerals instead of offering straight RO water.

Yes, of course, but arsenic in drinking water is a serious problem, not to be trifled with. In fact, the biggest poisoning event in human history was from arsenic in groundwater. If the OP has arsenic in their drinking water, they really have to do something to make sure not to consume it. A quick search shows that reverse osmosis is a popular solution in the US.

In my experience, low tech solar distillation works, but to produce enough for drinking water for one person would require a very large area, probably larger than the whole roof of their house -- and we did this in a climate that is ideal for solar distillation (lots of sun, and cold air). If necessary for drinking water, minerals can be added back in after purifying the water.