Differences in water qualities

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Updated - July 14, 2024

Updated 14.07.2024

The differences in water quality are not very obvious at first. Drinking water, waste water, rainwater, groundwater, seawater, mineral water and distilled water are the most commonly known classifications. In addition to these, there are other differences, such as mineral water, osmosis water, pure water and ultrapure water.

Let's start by mentioning "living water", which is currently booming in advertising. Some manufacturers advertise their systems with claims such as "energized", "bio-energy" or "energy module", which use "programmed natural high-energy spring water information" to restore the water's original freshness and vitality. However, they fail to provide any evidence of this that would stand up to purely scientific scrutiny and refer to the "company secret" (which could certainly be protected under patent law if it met the patent requirements ...).

Incidentally, "living water" is a biblical quotation, for example in John 4:14 "But whoever drinks of the water that I shall give him shall never thirst, but the water that I shall give him shall become in him a well of water springing up into everlasting life." or in John 7, 38 "He who believes in me, as the Scripture has said, out of his body will flow rivers of living watern."

Now to the differences between the various types of water available to us ...

Rainwater

Rainwater is already polluted when it rains down from the clouds by containing, in addition to dust particles, terrestrially generated, thermally (only decompose at temperatures above 400 °C) and chemically highly stable per- and polyfluorinated alkyl compounds (PFAS), many of which are not broken down but can be accumulated in human and animal tissue.

In areas with PFAS-contaminated drinking water, statistically significant increases in diseases such as diabetes mellitus, cerebrovascular diseases, Alzheimer's disease, heart attack, as well as higher mortality rates are recorded.

Since these compounds can only be incompletely broken down in sewage treatment plants, activated carbon is used for the long-chain PFAS.

100 ng/l PFAS contamination is stated to be ideal, while 300 ng/l is considered “tolerable for life”. Drinking water is no longer considered usable from 5 μg/l.

Rainwater has a conductivity of around 30 μS/cm.

Groundwater

Groundwater is contaminated with water-soluble and liquid components of uncontrolled stored waste, wastewater from leaks in sewage pipes, road drainage (e.g. tire wear, de-icing salts), fertilizers and pesticides, industrial and commercial wastewater, mineral oils, etc.

Nitrate pollution in particular poses a major health risk: even long-term use of water with levels above 16.75 mg/l can cause this risk The risk of developing colon cancer increases significantly.

Drinking water

The quality of drinking water is very high in terms of the impurities it contains. Drinking Water Ordinance (TrinkwV) Federal Law Gazette 159/2023 defined on June 24, 2023.

Reference is made to the above-mentioned VO for the ingredients and limit values.

The conductivity (parameter for the sum of all substances contained) of drinking water is set in Germany with a limit of 2.79 mS/cm (milli-Siemens per centimeter).

Mineral water

The Ordinance on natural mineral water, spring water and table water (Mineral and Table Water Ordinance) regulates the terminology, including the content (limit value) of naturally occurring components in natural mineral water.

The regulation valid from 01.01.2006 was supplemented by limit values for fluoride on 01.01.2008. The value for nickel was reduced from 0.05 to 0.02 mg/liter.

The following table contains a comparison of legally defined limit values for ingredients in drinking water and mineral water. Values in brackets in the table represent limit values applicable from 2028 or 2030.

Components	Limit value TrinkwV	Limit min/tableWV	Limits f. Infants
Antimony	0.005 mg/Ltr.	0.005 mg/Ltr.
arsenic	0.010 (0.004) mg/Ltr.	0.010 mg/Ltr.	<0,05 mg/Ltr.
Barium		1.0 mg/Ltr.
Lead	0.01 (0.005) mg/Ltr.	0.010 mg/Ltr.
Borat		30.0 mg/Ltr.
Chrome	0.025 (0.005) mg/Ltr.	0.050 mg/Ltr.
Fluoride	1.5 mg/Ltr.	5.0 mg/Ltr.	<0,7 mg/Ltr.
Cadmium	0.003 mg/Ltr.	0.003 mg/Ltr.
copper	2.0 mg/Ltr.	1.0 mg/Ltr.
manganese	0.05 mg/Ltr.	0.5 mg/Ltr.	<0,05 mg/Ltr.
Sodium	200.0 mg/Ltr.		< 20.0 mg/liter (low sodium)
nickel	0.020 mg/Ltr.	0.020 mg/Ltr.
nitrate	50 mg/Ltr.	50 mg/Ltr.	<10,0 mg/Ltr.
Nitrite	0.5 mg/Ltr.	0.1 mg/Ltr.	<0,02 mg/Ltr.
Mercury	0.0010 mg/Ltr.	0.0010 mg/Ltr.
Selenium	0.010 mg/Ltr.	0.010 mg/Ltr.
sulfate	250 mg/Ltr.		<240,0 mg/Ltr.
uranium	0.01 mg/Ltr.		<0,02 mg/Ltr.
Cyanide	0.050 mg/Ltr.	0.070 mg/Ltr.

Some manufacturers of so-called "living spring water" (or similar) systems refer to particularly poor mineral water qualities, which often do not even meet the requirements of the Drinking Water Ordinance. Analyses are not up-to-date and information on the labels may therefore not reflect the actual data of the content.

The extent to which such statements are tenable under competition law and, in particular, whether they are accurate, can be quickly clarified by brief correspondence with the manufacturer in question. In any case, you should not allow yourself to be fooled and do your own research to verify whether it may be a case of influencing buyers in an undesirable direction.

Sea water

Sea water is characterized by a comparatively high salt content, on average 3.5 %. The Baltic Sea has almost no salt at 0.2 – 2 % compared to the Dead Sea at 28 %. It has an average conductivity of 56 mS/cm.

Seawater desalination plants reduce the salt content to a drinkable minimum with the addition of calcium hydrogen carbonate. Since desalination is a very energy-intensive process, the waste heat from nuclear power plants (including on ships, aircraft carriers or nuclear submarines), but also from systems powered by coal, gas or oil, is often used.

Distilled water

Distilled water is produced by evaporation and subsequent condensation, using a very high amount of energy. This largely removes salts, organic substances and microorganisms. The conductivity is only 0.5 - 5.5 µS/cm (micro-Siemens per centimeter).

Multi-distilled water is offered in double or triple distillates and stored in quartz or platinum containers because traces of silica are released from glass vessels during cooking and would thus contaminate the distillate.

Osmosis water

Water from the reverse osmosis system is filtered several times, down to 0.02 µm and achieves a conductivity of 1 – 50 µS/cm.
It is generally assumed that a reverse osmosis system achieves around 10 % of the conductance that is available on the input side.
Although reverse osmosis does not achieve the level of purity of distilled water, it is useful for producing drinking water in terms of hygiene.

Ultrapure water

Ultrapure water is produced via a strongly alkaline mixed bed system and used industrially, for example in the semiconductor industry. The conductivity is 0.1 – 1 µS/cm.

Highly pure water

Highly pure water is required, for example, in medicine, the pharmaceutical industry and molecular biology and is produced in mixed-bed ion exchange systems. The conductivity is only 0.052 – 0.1 µS/cm.

Conductivity measurement (TDS)

In order to determine the conductivity of different types of water, a conductivity measuring device is required.

In addition to the pure conductivity measurement function, such devices also offer the determination of the TDS value (Totally Dissolved Solids) in ppm (parts per million). This value provides information about the dissolved solids in the form of ions, such as metals, salts, minerals.

The “measuring devices” that are often found in the “scene” in the range of around 20 – 50 euros can at best be viewed as “estimates”. They only provide a rough estimate and show a trend.

If you seriously want to have a reproducible and trustworthy measurement, you cannot avoid purchasing a device that is also available in a “calibrated” version or an uncalibrated one.
Ultimately, a calibration certificate “only” states that the device delivers a value that is exactly identical to a reference device in a central range at a standardized temperature.
This reference is missing in an uncalibrated device. So it can show a value just below or above this reference value.
Temperature compensation is important, as the measurement must always be electronically adjusted based on 25 °C in order to correspond to the actual value and to comply with standardization.

This means that two minimum criteria must be met: the function of conductivity and temperature measurement. If you still want to know the TDS value, you need the additional TDS measuring function.

In the best case scenario we are currently at approx. 390 euros, or approx. 530 euros including TDS function.