# DGH

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{{Short description|Unit of water hardness}}

{{Lowercase title}}

{{technical reasons|DGH|other uses|DGH (disambiguation)}}

{{No footnotes|date=August 2024}}

'''Degrees of general hardness''' ('''dGH or °GH''') is a [unit](/source/Units_of_measurement) of [water hardness](/source/Hard_water), specifically of general hardness. General hardness is a measure of the concentration of [divalent](/source/divalent) metal ions such as [calcium](/source/calcium) (Ca<sup>2+</sup>) and [magnesium](/source/magnesium) (Mg<sup>2+</sup>) per volume of water. Specifically, 1 dGH is defined as 10 milligrams (mg) of [calcium oxide](/source/calcium_oxide) (CaO) per litre of water. Since CaO has a [molar mass](/source/molar_mass) of 56.08 g/mol, 1 dGH is equivalent to 0.17832 [mmol](/source/mmol) per litre of elemental calcium and/or magnesium ions.

In water testing hardness is often measured in parts per million (ppm), where one part per million is defined as one milligram of [calcium carbonate](/source/calcium_carbonate) (CaCO<sub>3</sub>) per litre of water.  Consequently, 1 dGH corresponds to 10 ppm CaO but 17.848 ppm CaCO<sub>3</sub> which has a molar mass of 100.09 g/mol.

== See also ==
{{Portal|Water}}
* [Carbonate hardness](/source/Carbonate_hardness)
* [Hard water](/source/Hard_water)
* [dKH](/source/dKH)

== References ==
* {{Cite web |url=https://www.thekrib.com/Plants/CO2/hardness-larryfrank.html |title=Water Hardness |date=1997-12-16 |access-date=2011-11-04 |website=The Krib |last=Frank |first=Larry |archive-url=https://web.archive.org/web/20181024035241/https://www.thekrib.com/Plants/CO2/hardness-larryfrank.html |archive-date=2018-10-24 |url-status=live }}
* {{Cite web |url=https://www.cactus2000.de/de/unit/masswas.php |title=Wasserhärte [de] / Dureté de l'eau [fr] |date=2022 |access-date=2009-01-23 |website=Cactus2000 |last=Krüger |first=Bernd |archive-url=https://web.archive.org/web/20210222031923/https://www.cactus2000.de/de/unit/masswas.php |archive-date=2021-02-22 |url-status=live |language=de, en, fr |trans-title=Hardness of water }}

Category:Units of measurement
Category:Water chemistry

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{{water-stub}}

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