According to the 2004 report of the German Water and Wastewater Association (DWA) on damage, the short- to medium-term costs of repairing damage to water-treatment plants in Germany's sewage system are approximately 55 billion euros. It is reckoned that the same amount needs to be invested in short- to medium- term repair of water-treatment systems in the private sector (domestic and industrial). One of the causes is corrosion of construction materials by chemically-corrosive substances.