Temperature Tapwater: Guide values and effects

How cold does the water come out of the tap? Is hot water healthier than cold water? At what temperature does drinking water taste best? These are all questions that many of us ask ourselves in connection with the temperature of Tapwater . Would you like to know the answers to these frequently asked questions? Then you've come to the right place! 

In this Guidebook you will learn...

• what temperature Tapwater normally has, 
• whether hot or cold water is healthier in summer, 
• how the water temperature affects taste, pH value and bacterial growth
• and what the ideal temperatures of drinking water are.

Temperature Tapwater: What is normal? 

The average temperature of our tap water is around 15 °C. However, the water temperature in the pipes is not necessarily the same as the water straight from the tap. This is because while the pipes of the public supply network in this country generally run underground, this is no longer the case inside residential buildings. 

It can therefore happen that the temperature of the tap water from the tap deviates from 15 °C. This mainly happens when water pipes are poorly insulated or the water stagnates in the pipe over a long period of time. 

How long does it take for cold/hot water to come out of the tap?

There is no general answer to this question, as the lead time depends on many different factors, including: 

• Length of the pipeline
• Inner diameter of the pipe
• Pressure ratios
• Thermal conductivity of the pipes
• Pipe insulation
• Ambient temperature
• Temperature of the drinking water tank

Ideally, it should take a maximum of 30 seconds for cold or hot Tapwater to come out of the tap. 

Cold water vs. hot water temperature

Ideally, cold water should always have a temperature of less than 20 °C and hot water a temperature of over 60 °C . It is important that these values are maintained, as otherwise the conditions are ideal for the growth of bacteria and germs. Legionella in particular thrive between 25 and 55 °C - but more on this later.

Differences summer & winter

If the water pipes are laid underground, the outside temperatures and therefore summer and winter have little or no effect on the temperature of the drinking water. Only a major change in the ground temperature or the conditions in the residential buildings themselves can lead to changes in the water temperature under certain circumstances. 

The average temperature of 15 °C can therefore increase slightly in summer due to rising ground temperatures, among other things, but usually remains very good - provided the pipes are well insulated. The situation is similar in winter. Here too, temperatures remain at around 15 °C, but can drop slightly at times if the ground temperature is very low. 

In countries where the water pipes are laid above ground, the situation is different. Here, the temperatures can change massively depending on the time of year, as they are exposed to the influence of outside temperatures.

Tap water temperature and the human organism

Should you drink cold or warm drinks in summer? There are numerous myths surrounding this question, which can be summarized in two assertions: 

• Cold drinks cause more energy expenditure and heat production. As a result, we get warm. 
• Warm drinks increase our core temperature and stimulate sweating. As a result, we cool down more quickly. 

The fact is, however, that neither of these theories has been clearly confirmed from a scientific point of view ². However, there is a consensus that ice-cold drinks are unsuitable ³. Our stomachs often react sensitively to drinks that are too cold Tapwater . The result is stomach pain. 

In addition, many people find it unpleasant to drink ice-cold water, which automatically makes it harder to drink enough. This is particularly unfavorable in the summer months, as we already have an increased need for water at this time. 

The most important thing is therefore to drink enough - whether this is cold or warm Tapwater makes no difference in principle. 

Incidentally, the fact that warm or hot drinks are preferred in warm countries in summer has nothing to do with this! This has more to do with tradition and the generally poor water quality than with the supposed cooling effect. 

Drinking water temperature: Legal requirements according to the Drinking Water Ordinance?

The German Drinking Water Ordinance does not specify any guide values for the water temperature ⁴. However, such requirements can be found in the standard DIN EN 806-2 "Technical rules for drinking water installations", which is aimed at operators of drinking water installations ⁵.  

According to this, the cold water must not be warmer than 25 °C and the hot water must not be colder than 60 °C 30 seconds after it has been turned on.

The tap water temperature and its effects

Drinking water temperature has a significant effect on various aspects, above all taste, pH value and bacterial growth. Let's take a closer look at the whole thing. 

Flavor

The general opinion is that water tastes best between 8 and 12 °C. Anything below 5 °C is perceived as unpleasant, anything above 17 °C as stale. In principle, however, the ideal temperature is a question of personal taste. 

pH value

The pH value indicates whether a solution is acidic or alkaline. It is temperature-dependent, i.e. the pH value of the water changes depending on the temperature. Normally, the pH value of the water decreases with increasing temperature ⁶. 

Bacteria and germs

Bacterial growth increases from a water temperature of 20-25 °C. Legionella poses a particularly high risk. These rod-shaped bacteria love temperatures between 25 and 55 °C and only die at temperatures above 70 °C ⁷. 

For this very reason, it is important that cold water should ideally always be below 20 °C and hot water should always be above 60 °C . 

The ideal temperature of Tapwater

At an average of 15 °C, the temperature of Tapwater remains relatively stable throughout the year in this country thanks to underground pipes. Minor fluctuations are possible, but generally remain within manageable limits. 

Solange am Wasserhahn eine Temperatur von <20 °C bei Kaltwasser und >60 °C bei Warmwasser vorherrscht, ist alles in Ordnung und Sie müssen sich keine Sorgen machen. Bei wie viel Grad das Wasser am besten schmeckt und welche Wassertemperatur Sie im Sommer als Erfrischung bevorzugen, bleibt überdies ganz Ihnen überlassen. 

FAQs on drinking water temperature

How cold is Tapwater?

Tapwater has an average temperature of 15 °C. However, this temperature can vary due to external circumstances. 

At what temperature do legionella die? 

Legionella die at a temperature of 70 °C and above. However, a temperature range of 55 to 60 °C already prevents the growth of the rod-shaped bacteria. 

At what temperature is Tapwater healthiest?

No exact figure can be given for this. Both hot and cold water are good thirst quenchers. However, ice-cold water is not recommended as it can lead to unpleasant stomach cramps and pain. 

At what temperature does Tapwater taste best?

In principle, this always depends on individual taste. As a rule, water between 8 and 12 °C tastes best to most people. Water below 5 °C, on the other hand, is perceived as unpleasant and water above 17 °C as stale. 

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