Water pH value: The ideal pH value for our drinking water

Our water is constantly checked for different values. One of these values is the so-called pH value. It tells us whether a solution - in this case our water - is acidic or alkaline. As humans are dependent on a balanced acid-base balance, our drinking water must maintain a certain pH value.

In this article, we therefore take a closer look at ...

... what the pH value is,
... what acids and bases are,
... what significance the pH value has for the human body,
... what pH value water has,
... what the optimum pH value for drinking water is,
... how you can measure the pH value in water
... and how you can reduce or increase the pH value in the water.

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Updated on: 25.01.2022

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What is the pH value?

The pH value (lat. potentia hydrogenii) is a measure of the concentration of hydrogen ions in a solution. If there are many hydrogen ions in a solution, it is acidic. If, on the other hand, there are only a few, the solution is said to be alkaline.

The pH value is usually given on a scale from 0 to 14, with 7 representing the neutral mean value. Anything below this mean value is referred to as "acidic". Anything above is called "basic" or "alkaline". The further away the value is from 7, the stronger the acid or base.

pH value: acidic or alkaline?

Put simply, the pH value indicates whether an aqueous solution is acidic or alkaline. But what exactly does that mean?

We encounter acids and bases every day - be it in coffee at breakfast, in tomato salad at lunch or in soap when washing our hands. Coffee, tomatoes and vinegar are acids, while soap is a base. The names of liquids often tell us something about their classification on the pH scale. Stomach acid, for example, is a classic representative of acids and caustic soda is an important base.

Substances classified in pH value table from basic to acidic

Without acids and bases, many things in our lives would not be so easy. They help us to preserve food, digest food, remove dirt and much more. Many basic chemical processes would not be possible without acids and bases.

But be careful:

Some acids and bases are dangerous for us humans in excessive concentrations. These include sulphuric acid, nitric acid and ammonia, which are considered irritating or corrosive and can cause inflammation and tissue destruction.^[1]

The pH value and the human body

Our body is dependent on a balanced acid-base balance. All of our body fluids have a certain pH value, which must be maintained as well as possible. If there are major deviations from these ideal values, the body can no longer compensate for this and reacts with illnesses ^[2]. In the worst case, serious disorders of the acid-base balance can even lead to death.

If we are over-acidified (= acidosis), the transport of oxygen through our organism is considerably restricted and an oxygen deficiency occurs. Typical symptoms include listlessness, tiredness and muscle and joint complaints.

If the pH value in our body is too high over a longer period of time (= alkalosis) - i.e. strongly alkaline - this also has a negative effect on our health. Well-known signs of this are dizziness, hyperventilation and muscle cramps.

Our skin also has a protective acid mantle. With its slightly acidic pH value of 5.5, it protects us from pathogens. Frequent use of alkaline care products (e.g. when showering) attacks this protective layer. It is therefore recommended to use pH-neutral products for hair shampoo, shower gel, creams and the like.

What is the pH value of water?

According to the Drinking Water Ordinance, drinking water in Germany must have a pH value of 6.5 - 9.0 - in reality, it is usually between 7.0 and 8.5 ^[3]. In some areas, however, the pH value of groundwater is significantly lower due to acid rain ^[4]. In such cases, the water must be deacidified using special processes.

But not all water is the same - different pH values are measured depending on the type:

pH value for different types of water:

Type of water	pH value*
Distilled water	5
Tapwater	7,0 - 8,5
Rainwater	5,6 - 5,8
Mineral water (carbonated)	5,5 - 6,5
Heating water	8,2 - 10
Lime water	12

*The values stated are average values. There may be deviations from these values.

Incidentally, a higher pH value tends to go hand in hand with higher water hardness. Soft water therefore tends to have a lower pH value. However, this is merely an observable trend and not a direct correlation!

The pH value in Germany's Tapwater : Munich, Berlin, Cologne and Co.

The pH value of tap water in Germany is generally between 7.0 and 8.5. The pH value varies not only from state to state and from city to city. Fluctuations can even be seen within a city. This is due to the fact that water is supplied by different waterworks and sources.

The following graph shows some examples of the various pH values in Germany. These are merely rounded average values from selected municipal utilities or supply areas. The actual pH value on site may therefore differ.

The optimum pH value for drinking water

The pH value of our drinking water is strictly controlled. If the samples do not meet the specifications, the regional water suppliers intervene and regulate the water. The optimum pH value depends on the one hand on the material resistance of the pipes and on the other hand on human health.

From an economic point of view, a constant pH value is extremely important for municipal utilities and homeowners. This is because the pH value has a significant impact on the choice of material for the water pipes. If these requirements are not met, there is a risk of corrosion.

If the pH value is below 7.0, copper pipes must not be installed.
If the pH value is below 7.5, there is a risk of corrosion for galvanized steel.
At a pH value below 6.5, materials containing cement are attacked.

We have already explained above that the pH value has a significant effect on our acid-base balance. In addition, however, too low pH values dissolve copper more easily, which is particularly dangerous for babies and small children ^[5]. A slightly acidic environment also provides an ideal breeding ground for legionella.

This is precisely where Alb Filter drinking water filters come into play. Although they do not affect the pH value, they do filter excess copper and unwanted legionella out of the drinking water. In this way, you can offset some of the negative aspects of a low pH value yourself.

If all these factors are taken into account, the optimum pH value of water is between 7.0 and 8.5.

Measuring the pH value in water: step by step

The pH value can basically be measured in three different ways: using potentiometry, with an ion-sensitive field-effect transistor or with the help of indicator dyes.

The first two test methods are physically somewhat more complex and are mainly used in laboratories or other professional environments. The measurement using indicator dyes - for example using litmus - can be easily carried out at home. All you need is a pH test kit with test strips and a comparison table. These are available from pharmacies and various specialist stores locally or online.

The test procedure itself is very simple and can be completed in just a few minutes. Regardless of the manufacturer, it usually involves the following three steps:

Hold the test strip in the solution to be tested for a few seconds.
Remove the test strip and wait approx. one minute.
Compare the test strip with the comparison table to read the pH value.

Reduce or increase the pH value in the water

For normal consumption, private individuals generally no longer need to lower or raise the pH value of the water - this is taken care of by the regional water suppliers. However, there are some situations in which a certain pH value is required, for example for an aquarium or swimming pool.

pH value in the aquarium

For fish, changes in the pH value mean great stress. It is therefore important that the preferred pH value of the fish living in the aquarium at home prevails. This desired value does not always match that of the tap water.

In such cases, it is necessary to lower or increase the pH value. A supply of CO2 lowers the pH value. More surface movement (flow) drives out C02 and thus increases the pH value. If this does not help, you can also use special water conditioners.

pH value in the swimming pool

Due to numerous influencing factors, the pH value in the pool water can fluctuate. Examples include rainwater or impurities from leaves, hair, etc. Ideally, the pH value in swimming pools should be between 7.0 and 7.4. If it deviates from this, you can intervene with water conditioners such as pH-Plus and pH-Minus.

pH value: Drink water without hesitation

The pH value plays a key role in determining the quality of our drinking water. If it is permanently too low, there is a risk of corrosion in certain materials and a risk of acidosis for us humans. If it is too high, it can lead to alkalosis in our organism in the long term.

It is therefore all the more important that a value of 6.5 - 9.0 or ideally 7.0 - 8.5 is maintained - the regional water suppliers ensure this by taking numerous samples. If the pH value does not correspond to these values, it is regulated. So at least when it comes to the pH value, you can drink your Tapwater without hesitation.

FAQs on the pH value of water

What pH value of water is good?

The optimum pH value of water is between 7.0 and 8.5. Lower values are not ideal either for the water supply network or for humans.

What pH value of water is dangerous?

The German Drinking Water Ordinance stipulates a pH value of between 6.5 and 9.0 for drinking water. The values should not deviate from this, as negative effects for humans and the environment can then no longer be ruled out.

Is water acidic or alkaline?

Water generally has a neutral to slightly alkaline character. More precisely, the pH value of tap water is generally between 7.0 and 8.5.

Why is the pH value of water not always neutral?

The pH value always depends on the concentration of hydrogen ions. If this concentration is high, the pH value is low, i.e. the water is acidic. If the concentration of hydrogen ions is low, the pH value is high, i.e. the water is alkaline.

At what pH value does lime dissolve?

Lime dissolves at a pH value of less than 7.

Is it possible to measure the pH value without test strips?

The pH value can also be determined without test strips. However, these are more complex physical methods that are primarily used in the laboratory.