tap water
Tap water is a collective term for technically in water pipes ( piping ) supplied to or engaged there Knitting water . In common usage, tap water is usually equated with drinking water . There are, however, types of water supplied through pipes that have no drinking water quality, but as process water are used.
Differentiated line systems
Different water pipes have to be operated next to each other for the different purposes. For example, in the chemical industry, for. T. three or more pipe networks installed in which water of different quality or temperature is transported.
Sometimes there are two water distribution systems in cities ; especially in the southern countries where potable water is scarce, so also today, the fire-fighting water for hydrants the fire service carried over a independent of the drinking water supply mains. In Central Europe, however, after a directional uncertainty in the 19th century, the public water supply decided in favor of a standardized water pipe, so that it only supplies water with drinking water quality. Even in households and public buildings, domestic water, e.g. B. for flushing toilets. Today, this usable water for household use is mostly not obtained from the water supplier, but is usually obtained from self-collected rainwater . However, thanks to the advances in water treatment technology , wastewater can also be reprocessed into service water . For such uses, a second water pipe system must be installed inside the house next to the drinking water network.
Quality of drinking water in the form of tap water
The greatest threat comes from the condition of the network and the water pipes used. Where the pipe network is poorly rehabilitated (e.g. in Great Britain with water losses of around 30%), substances from the soil can also penetrate the pipes. Until 1990, asbestos-cement pipes were used in Germany for large water pipes in the public supply network .
The Drinking Water Ordinance regulates that the drinking water must be flawless not only at the point of transfer into the house, but also in the drinking water installation up to the tap . Accordingly, house water pipes must also be renovated by the landlord. Until 1960, lead pipes were still used in houses . T. can still lie today. Lead can cause a wide variety of diseases in humans. Babies and children in particular are at risk from drinking water containing heavy metals, such as drinking water contaminated with copper . According to the Drinking Water Ordinance, the limit values for lead and copper are 25 µg Pb / l (from 2013 10 µg / l) and 2000 µg Cu / l. A release from the pipe to the drinking water takes place only rarely. It is important to have a sufficient layer of lime on the inside of the copper pipes. This lime layer can only form if the drinking water is in lime-carbonic acid balance. According to the Drinking Water Ordinance, the waterworks are obliged to check this. Groundwater can be aggressive, especially in areas with little lime. If under a dripping tap verdigris traces show, so this is a clear sign of insufficient Kalkschutzschicht in the copper pipes. In this case a specialist or the local water supplier should be asked for advice. Of stagnant water occurs when water on the way from the source to the tap in the strands of wire longer than has stopped 4 hours. In the case of stagnant water, chemical, physical and microbial processes lead to the formation of biofilms . Germs that collect and multiply in the biofilm reach the consumer when the water is withdrawn. According to the Federal Environment Agency (UBA), this represents a health risk. Therefore, stagnant water should not be used as drinking water because of possible germs and other pollution and should be allowed to flow until the noticeably cooler water comes from the public pipe.
If water is not taken from the water pipes sufficiently and constantly, for example due to demographic change ( population decline ), there is also a high risk of germ formation. The water suppliers must counteract such problems with flushing and emergency withdrawals. An example of this are some East German municipalities, in which water consumption has fallen so sharply in recent years that regular countermeasures have been required by the water supplier. In the long term, dismantling or converting the water system (semi-central or decentralized treatment) can make more sense than maintaining a central system with long pipes.
Substances polluting tap water, including germs, can be removed with the use of a nanofiltration system or osmosis system. These systems have been used for a long time in the pharmaceutical and food industries; Devices are also available for private households or for semi-central use in small settlements. The tap water in Germany is almost germ-free due to the extensive controls and can therefore also be used for babies and small children.
Legionella form in lukewarm water. There were also problems of this kind in Germany, especially in the hot water pipe systems of hospitals and hotels. Legionella cause Legionnaires' disease, which can be fatal .
If the recommended amount of drinking water is covered with tap water instead of bottled water, the microplastic uptake can be reduced from 90,000 to 4,000 parts per year.
Other names
Colloquially, drinking water from the pipe is also referred to as crane (s) water , Krane (n) berger or Kranenburger , derived from the West Central German term crane for water tap. Küpper's dictionary of colloquial German says: “Joking increase in the value of the water from the crane based on the model of wine names or beer brand names. Since 1900 at the latest. ”Also“ Rohrperle ”. In Switzerland, Health Promotion Switzerland propagates the name “Hahnenburger”. Similarly in French: “Chateau (de) la pompe”.
literature
- Thomas Kluge , Engelbert Schramm : water problems: the history of drinking water. Volksblatt, Cologne 1988 (2nd edition), ISBN 3-923243-38-3 .
- Matthias Koziol, Antje Veith, Jörg Walther: Are we facing a system change in water supply and wastewater disposal? Sectoral boundary conditions and options in the urban technology transformation process. Berlin 2006, netWORKS Papers 22 ( PDF; 1.4 MB ).
- Hans-Jürgen Leist: Water supply in Germany - criticism and possible solutions. oekom Verlag, Munich 2007. ISBN 978-3-86581-078-6 .
Web links
- List of drinking water laboratories in North Rhine-Westphalia ( Memento from June 19, 2008 in the Internet Archive )
Individual evidence
- ↑ Kieran D. Cox, Garth A. Covernton, Hailey L. Davies, John F. Dower, Francis Juanes, Sarah E. Dudas: Human Consumption of Microplastics. In: Environmental Science & Technology. 2019, doi : 10.1021 / acs.est.9b01517 .
- ↑ Kluge - Etymological dictionary of the German language . 24th edition, ISBN 978-3-11-017473-1 .
- ↑ Heinz Küpper: Dictionary of German colloquial language . Stuttgart 1987, article Kraneberger .
- ↑ About Hahnenburger , accessed on June 20, 2016.
- ↑ Chateau de la Pompe. Retrieved August 26, 2009 .