On 5 May 2007, the new law on the environmental compatibility of detergents and cleaning agents (Detergents and Cleaning Agents Act - WRMG) came into force. Amongst other things, it now regulates how the hardness ranges for drinking water must be specified. Instead of the previous four water hardness ranges, only three will apply in future. The new designations are soft, medium and hard.
New categorisation into water hardness ranges
This classification has been in force since 5 May 2007:
| Hardness range | Millimoles of calcium carbonate per litre (mmol/l) | German degrees of hardness (°dH) |
| soft | up to 1.5 | 0-8,4 |
| medium | 1,5-2,5 | 8,4-14 |
| hard | over 2.5 | over 14 |
Drinking water hardness in Giessen
Giessen is supplied partly with water from the Queckborn waterworks and partly with water from the Central Hesse Waterworks Association (ZMW). As the water does not just come from one source area, there are different water hardnesses in the city. The water from Queckbörn is medium hardness, but just on the edge of soft. The water from the ZMW falls completely into the soft hardness range. Depending on the street, the water hardness therefore varies between soft and medium.
If an SWG customer wants to know the hardness of the water in their home, they can call the service telephone on 0180 22 11 100 or ask for this information in person at the infoCentre on Marktplatz. On the SWG website (www.stadtwerke-giessen.de), customers can enter their district under the keyword "water quality" to find out the water hardness there.
SWG customers can also read a detailed report on the subject of water hardness in the next issue of the customer magazine elahn. It will be published at the end of June 2007.
Correct dosing protects the environment
Knowing the water hardness is important in order to dose detergents and cleaning agents correctly. Most detergents are labelled on the packaging with the appropriate dosage for each degree of hardness. Using too much detergent not only puts a strain on your wallet, but also on the water. This is because many detergents contain phosphates, among other things, which over-fertilise rivers and lakes with nutrients. As the water from Queckborn only just reaches the medium hardness level, SWG recommends that all customers only use detergents and cleaning agents for soft water hardness.