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The chemical composition of water



The chemical composition of water is an important indicator for judging its effect on health. The factors that I consider to be the most important are:

  • TDS: dissolved residues. It is the content of matter other than water. In other words it is the concentration of minerals and other substances dissolved in the water. Water with a dissolved residue concentration of less than 100 ppm (parts per million) is very pure. However, there are highly mineralized waters, such as that from the German Gerolsteiner spring which contains 2500 ppm of dissolved residues and is said to be very good for health. Drinking mineral water can thus be beneficial for health if you need to remineralise, but can ultimately clog up the body. Obviously, the effects on health will also depend on the quality of the substances contained in the water.

  • The pH. It is the acidity of the water. A pH between 0 and 7 is acidic. A pH of 7 is neutral. A pH above 7 is alkaline. An alkaline pH is an indicator that the water has not been in contact with the atmosphere, including pollution that acidifies it.

  • The absence of toxic heavy metals. The water must not contain lead (Pb) or mercury (Hg).


Here are the analyzes of four waters: the water from the Orthevielle spring in the Landes is renowned for its purity and has been drunk by people in excellent health for decades. It is indeed the water that contains the least residue. Its alkaline pH indicates that it has not been in contact with atmospheric contaminants.


Lourdes water is known throughout the world for its therapeutic and even healing properties. Its chemical composition reveals that it is a little more mineralized than Orthevielle water, while remaining very pure.


Finally, there are very few differences between tap water before and after filtration. Given that the quality of tap water varies according to its composition when passing through the treatment plant, it can be assumed that the time of sampling corresponds to a time when this water was of good quality. This may explain the similar result after filtration: there was almost nothing to filter. One can also question the efficiency of the filter. It is noted in particular that there are 3 ppm more residues. However, this is so small that it can be attributed to the margin of error.

Factor analyzed

Spring of Orthevielle

Lourdes Water

Tap water from B.D. in the Basque Country

The same tap water, filtered

TDS or dissolved residues (ppm)

80

123

125

128

pH by electronic pH meter

8.3

9.7

8.8

8.6

Total Alkalinity (mg/L)

0

120

120

120

pH tested by strip

6.2

8.4

7.8

7.8

Cyanide acid (mg/L)

0

0

0

0

Carbonate (mg/L)

0

300

300

300

Hardness (mg/L)

0

100

100

100

Total Chlorine (mg/L)

0

0

0

0

Free Chlorine (mg/L)

0

0

0

0

Bromine (mg/L)

0

0

0

0

Nitrate (mg/L)

10

0

10

10

Nitrite (mg/L)

0

0

0

0

Iron (mg/L)

0

0

0

0

Chromium / Cr (VI) (mg/L)

0

Between 0 and 2

Between 0 and 2

Between 0 and 2

Lead (mg/L)

0

0

0

0

Copper (mg/L)

0

0

0

0

Mercury (mg/L)

0

0

0

0

Fluoride (mg/L)

0

0

0

0



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