Editing Distilled water (section)

==Equipment to distill water==
[[File:Double Distilled Water Unit.jpg|thumb|Typical laboratory distillation unit]]

Until World War II, distilling seawater to produce [[fresh water]] was time-consuming and expensive in fuel. The saying was: "It takes one gallon of fuel to make one gallon of fresh water."{{citation needed|date=August 2018}} Shortly before the war, Dr. R.&nbsp;V. Kleinschmidt developed a compression still, which became known as the Kleinschmidt still, for extracting fresh water from seawater or contaminated water. By compressing the steam produced by boiling water, {{convert|175|gal|abbr=on}} of fresh water could be extracted from seawater for every gallon ({{convert|1|gal|disp=out}}) of fuel used. During World War II this equipment became standard on Allied ships and on trailer mounts for armies. This method was in widespread use in ships and portable water distilling units<ref>{{cite book |url=https://books.google.com/books?id=2yADAAAAMBAJ&q=popular+science+February+1946&pg=PA89 |title=Popular Science |author=Bonnier Corporation |date=February 1946}}</ref> during the latter half of the century. Modern vessels now use [[Flash evaporation|flash-type evaporators]] to boil seawater, heating the water to between {{convert|70|and|80|C}} and evaporating the water in a vacuum; this is then collected as condensation before being stored.

[[Solar still]]s can be relatively simple to design and build, with very cheap materials.<ref>{{cite web |url=http://www.thefarm.org/charities/i4at/surv/sstill.htm |title=Solar Water Distiller |access-date=2009-09-03 |url-status=dead |archive-url=https://web.archive.org/web/20090819050013/http://www.thefarm.org/charities/i4at/surv/sstill.htm |archive-date=2009-08-19 |publisher=thefarm.org}}</ref>

Distilling water with commercial equipment will almost completely remove all dissolved minerals such as calcium, magnesium, sodium, fluoride, potassium, iron, and zinc leaving a TDS of <1PPM, and reduce its electrical conductivity to <2 μS/cm. Typical tap water has electrical conductivity in the range of 200–800 μS/cm. The pH of distilled water is always slightly lower than 7 (neutral) because distilled water will absorb small amounts of carbon dioxide gas from the atmosphere which forms traces of carbonic acid and lowers the pH of distilled water to around 5.8 pH (very weakly acidic).<ref>{{Cite journal |title=The pH of water from various sources: an overview for recommendation for patients with atopic dermatitis |journal=Asia Pacific Allergy| year=2013 |language=en-GB|doi=10.5415/apallergy.2013.3.3.155| last1=Kulthanan | first1=Kanokvalai | last2=Nuchkull | first2=Piyavadee | last3=Varothai | first3=Supenya | volume=3 | issue=3 |pages=155–160 |pmid=23956962 | pmc=3736366 }}

{{Citation | year=2022 | title=Distilled Water pH | url=https://www.golyath.co.uk/blog/distilled-water-ph/ | access-date=22 February 2023}}

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