Do you require help or further information?
Contact us! We are happy to advise you:
fzexalabs.com
+91 9810506498
- Types of Water
- What can affect the quality of water?
- Testing in the laboratory vs. Test Kits
- Relevant limit values for drinking water analysis
- Microbiological testing of drinking water
- Water testing to check the water quality
- Accreditation of laboratories of the Tentamus Group
- How does sampling for water testing work?
- How are the results of water testing provided?
- Who should have their water analysed in a laboratory?
- Overview of laboratories for water testing of the Tentamus Group
What types of water are there?
According to legal requirements, water for human consumption can be roughly divided into:
- Service water (e.g. gray water)
- Swimming and bathing pool water
- Drinking water (e.g. mineral water)
Each of these waters has its own legal requirements for quality and purity. Even if these waters are not intended for drinking, they must comply with minimum legal requirements regarding their quality. This water testing must be carried out by an approved laboratory.
Is tap water safe to drink?
Drinking water is water that is “intended for human consumption,” i.e., when it is used for drinking, cooking, and preparing food as well as beverages. This also includes the use of drinking water for personal hygiene such as showering, as well as cleaning objects that come into contact with the body or food.
Water is also considered drinking water if it is used in a food processing plant in the manufacture of products. According to the law, this must be safe, edible and free of pathogens. That is, tap water is safe to drink because it is intended for human consumption and therefore must be safe for humans.
However, the quality of tap water is only guaranteed by the public utility company up to the house connection. However, the connecting piping system can have a great influence on the quality of the drinking water, for example, old lead pipes or other unacceptable materials that negatively affect the drinking water.
Is well water safe to drink?
These bacteria can settle and multiply in the domestic installation.
Anyone who uses well water as drinking water has an obligation to notify the relevant health authority.
We are also happy to support you with our professional expertise in the classification of your water.

What can affect the quality of water?
- Colony count at 22°C and 36°C
- E. coli
- Coliform bacteria
- Enterococci
- Legionella
- Clostridium perfringens
- Pseudomonas aeruginosa
Pollutants that affect quality and therefore health include:
- Sediment, turbidity
- Nitrate, nitrite
- Ammonium
- Heavy metals
- Pesticides
- Hydrocarbons
Furthermore, the quality is determined by the mineral composition of the water:
- Hydrogen carbonate
- Calcium
- Magnesium
- Potassium
- Iron
- Sodium
- Sulfate
- Chloride
Calcite/calcium carbonate ( scale)
Advantage of water testing in the laboratory over test kits
- Control of the precision of the measured value – Suitable/calibrated equipment and validation of the procedure
- Control of the measured value reference – Important is the sampling in the “right” part of the plant
- Control of the measured value risk – Interference factors must be excluded/considered (this applies in particular to the use of kits and for microbiological samples)
- Control of the accuracy of the measured values – Precise measurement results through special test procedures
- Control of the interpretation of the measured values – Which influencing factors have to be considered?
- Control of the measured value evaluation – Is the measured value valid?
- Control of the effect of the measured value – Is there a temporary increase/a systemic problem?
- Appropriate reaction – Which measures have to be taken/ what are the consequences?
Through good planning of sampling with regard to relevant taps and the type of water samples, reliable and coherent results are obtained through water testing. Based on these results, action plans can be drawn up and possible sources of contamination can be detected in order to ensure the quality of the water or to prevent quality losses and possibly damage to the installation.
Microbiological testing of drinking water
Landlords, owners and operators must ensure that drinking water is regularly tested by means of reliable water testing.
Limit values for chemical parameters
Chemical substances must not be present in concentrations that would harm humans. This can be detected with the help of chemical water testing.
In the following, we list essential limit values for heavy metals. The entire table can be found in the Ordinance.
| Parameter | Grenzwert mg/l |
|---|---|
| Arsenic | 0,01 |
| Lead | 0,01 |
| Manganese | 0,05 |
| Copper | 2.0 |
| Nickel | 0,02 |
Relevant limit values for drinking water analysis
- Determination of the colony count at 22°C and 36°C – The total colony count in the water is determined by exposing the water sample to incubation temperatures of 22°C and 36°C. The results do not provide information about the presence of a specific germ, but about the general microbiological status of the sample. The results do not provide information about the presence of a specific germ, but about the general microbiological status of the sample.
- E. coli – Escherichia coli (E. coli) belongs to the coliform bacteria and is found in the intestine. It is an indicator germ. If E.coli is found in a water sample, it is an indicator of poor hygiene and indicates faecal contamination.
- Enterococci – Enterococci are intestinal bacteria of humans. The presence of enterococci in water is also an indicator of faecal contamination.
- Coliforms – Coliform germs comprise a whole family of germs. Among them are also pathogenic germs – i.e. bacteria that can make people ill.
- Clostridium perfringens – Clostridium perfringens are gram-positive, anaerobic bacteria. They belong to the intestinal flora of humans and animals. Drinking water is tested for Clostridium perfringens if the water comes from surface water or is influenced by it. This also means mandatory testing for wells that are less than 10 m deep.
- Pseudomonas aeruginosa – Pseudomonas aeruginos belongs to the gram-negative bacteria and can occur wherever there is sufficient water. This germ is particularly resistant and belongs to the slime-forming bacteria.
- Legionella – Legionella are gram-negative, aerobic bacteria that are transmitted via droplets. This means that an infection is caused, for example, by inhaling water vapour containing legionella. They are mainly found in hot water pipes. According to the Drinking Water Ordinance, the technical action value is 100 CFU/100 ml.

Water testing to check the water quality
The requirements for drinking water analysis are regulated in the Drinking Water Ordinance (TrinkwV). The laboratories of the Tentamus Group are approved, among other things, for the sampling and analysis of drinking water. The annex to the Drinking Water Ordinance lists limit values for the microbiological and chemical parameters that are tested in our water testing.
Limit values for chemical parameters
Testing water hardness
| Total hardness (dH°) | Millimol Calcium Carbonate / l | Range |
|---|---|---|
| < 8,4 | < 1,5 | soft |
| 9,4 – 14 | 1,5 – 2,5 | medium hard |
| > 14 | > 2,5 | hard |
Accreditation of laboratories of the Tentamus Group
- Expert knowledge and advice
- Requirement profiles for water
- Sampling planning
- Sampling
- Water testing
- Accompanying recommendations for measures

How does sampling for water testing work?
In water testing, the sampling of drinking water depends on the purpose of the analysis:
Thus, there are different purposes for sampling. Each purpose has its own requirements for water sampling and provides specific results. If these requirements are disregarded, the results will be of limited or no significance.
For example, when sampling from the water supplier for a microbiological examination, the water sample is taken at the transition from the water supplier to the house. If a treatment plant is installed, sampling must also be well timed in many cases. Otherwise, only limited or no meaningful results are obtained.
Under certain circumstances, limit values may be exceeded, which can be avoided with good planning in advance. Because there are so many possibilities for contamination, good planning and execution of sampling is mandatory for meaningful water testing.
How are the results of water testing provided?
Who should have their water analysed in a laboratory?
- Entrepreneurs and owners of water supply systems are obliged to carry out water testing.
- Service providers where customers come into contact with water, such as dentists, should also have their water tested regularly, as hygiene and safety are of particular importance here.
- Commercial and industrial facilities with a central water heating system are also obliged to have the water checked regularly if they have a storage water heater or a flow-through water heater with a total capacity of more than 400 litres or if a volume of 3 litres is exceeded from the outlet of the water heater to the first tapping point.
- Private households can have the general quality of their water tested with the help of water testing or do so on suspicion, e.g. if they suspect legionella or heavy metals.
- Landlords of apartment buildings are responsible for the water quality and are obliged to have it checked. Here, the public health department decides which parameters must be tested for in addition to legionella. One- and two-family houses are exempt from this obligation.
- Large public systems are obliged to carry out a legionella examination once a year and large commercial systems every 3 years.
Overview of laboratories for water testing of the Tentamus Group








