Water hardness report

Hardness values
Zone	mg/l asCa	p.p.mas CaCo₃ mg/l	⁰Clarke	⁰F French	⁰H dH German	mili-mols/ litre mmol/l	grains/ gal	Fluoride mg/l	Nitrate mg/l	pH
Cambridge North	129	323	23	32	18	3.2	23	0.16	33	7.3
Cambridge South	126	315	22	32	18	3.2	22	0.15	37	7.3
Croydon	91	228	16	23	13	2.3	16	0.04	1	7.5
Linton	126	315	22	32	18	3.2	22	0.13	34	7.4
Heydon	130	325	23	33	18	3.3	23	0.17	39	7.3
Coton	111	278	19	28	16	2.8	19	0.15	36	7.3
Sawston	113	283	20	28	16	2.8	20	0.16	32	7.4
Odsey	120	300	21	30	17	3.0	21	0.06	40	7.2

Hard water is water that has a high mineral content (mainly calcium and magnesium ions).

The simplest way to determine hardness of water is to lather a bar of soap or clean your teeth. In soft water it is easy to get a lather or a froth, but it is not possible to do this using hard water.

More exact measurements of water hardness are outlined below.

Generally the total water hardness is the sum of the calcium and magnesium sulphates and/or chlorides in the water. This is read as parts per million (ppm) of weight/volume in the water of calcium carbonate (CaCO₃)

Definitions

Mg/l as Ca – The amount of calcium milligrams in a litre.

ppm as CaCO₃ mg/l –ppm is one milligram of calcium carbonate (CaCO₃) in a litre of water

Millimoles/litre (mmol/l) - The hardness of water depends on its content of calcium and magnesium salts. When measuring the total hardness, the sum of these salts is determined and in modern day terminology is expressed in millimoles a litre (mmol/l). A millimole refers to the amount of calcium and/or magnesium atoms within a litre

Previously hardness was measured in “degrees” and it was important to differential between English, French and German interpretations.

English (^O Clarke) - One degree Clark is defined as one grain (64.8 mg) of calcium carbonate per Imperial gallon (4.55 litres) of water, equivalent to 14.254 ppm.

French (^OF French) - One degree French is defined as 10 milligrams of calcium carbonate per litre of water, equivalent to 10 ppm.

German (^OH dH German) - One degree German is defined as 10 milligrams of calcium oxide per litre of water. This is equivalent to 17.848 milligrams of calcium carbonate per litre of water, or 17.848 ppm.

Grains/gal – this is defined as one grain (64.8 mg) of calcium carbonate per US gallon (3.79 litres)

The following values generally apply to these terms: