Seventy percent. That’s the potential amount of Dresden’s drinking water needs that Wasserwerk Hosterwitz can cover. Welcome to a place that has been vital to Dresden for over a century. Wasserwerk Hosterwitz is located east of Dresden’s city center in the Hosterwitz district. Built between 1905 and 1908, this waterworks provides about 20 percent of Dresden’s drinking water. The plans were designed by city building director Hans Erlwein.
Let’s dive into its history. Wasserwerk Hosterwitz started operating on December 11, 1908. It was Dresden’s third waterworks, following Wasserwerk Saloppe and Wasserwerk Tolkewitz. Initially, the water treatment involved extracting groundwater enriched with bank filtrate. This water was then pumped directly into Dresden’s water distribution system.
As Dresden’s need for drinking water grew, Wasserwerk Hosterwitz expanded between 1928 and 1930. The goal was to supplement the available natural groundwater supply. Elbe River water was pumped, pre-cleaned by seeping through gravel beds, and then extracted again through wells. A new filter stage was added to treat all the raw water. This was necessary because the Elbe’s water quality had decreased due to pollution. During this expansion, electricity replaced steam as the driving energy.
By the 1970s, Wasserwerk Hosterwitz’s capacity was once again too small. Major renovations began in 1983 after thorough preliminary studies. The aim was to increase the drinking water output to 72,000 cubic meters daily. New technological modules and more efficient treatment stages achieved this goal.
After the reunification of Germany, further improvements were made. The introduction of a filter system with activated carbon further enhanced the water quality. Even today, the plant sources its raw water from three sources. These are natural bank filtrate, artificially increased infiltrate, and additional groundwater flowing from the land side. This makes Wasserwerk Hosterwitz unique in Dresden.
The old factory buildings, designed by Hans Erlwein, were in operation from 1908 to 1992. Because the buildings are protected as historical monuments, the operating facilities were moved to a new building between 1983 and 1992. The old buildings were preserved as empty industrial monuments. After the relocation, the buildings were restored to their original appearance. The reconstruction of the roofs began in 1994. They regained Erlwein’s dormers, beaver-tail coverings, and copper gutters.
Today, the old river water filter hall houses the waterworks’ social and office area. Pumps for supplying Dresden’s higher elevations, such as WeiBig, are located in the former machine house. The former clean water filter hall is leased to a branch of the German Association for Gas and Water Technology Center’s technology center. Architect Eberhard Pfau has created a house within a house inside the hall. The office wing does not completely fill the hall. From the open space, you can see how the old roof extends far beyond the new interior building. In addition to the office wing, space is kept free in the hall for additional technical equipment.
Following the 2002 Elbe flood, 5.3 million euros were spent to repair the waterworks. The pumps, chemical storage facilities, and dosing systems were restored. The electronic measuring and control technology and the power supply had to be replaced. The waterworks was able to return to the grid after four and a half months of repairs.
Many of the 144 wells still in use today date from 1932 to 1934. Each well can extract 100 cubic meters of water per hour. The wells are up to 22 meters deep and two to three meters in diameter. The wells have been gradually renovated since 2007. The current maximum treatment capacity is 72,000 cubic meters per day. In 2015, ten million cubic meters of water were treated. Half came from raw water from the Elbe and half from free groundwater inflow.
The sand from the infiltration basins must be removed and cleaned every 20 years. Approximately 1,500 cubic meters of sand are washed in a mobile cleaning system using excavators. Weeds, dirt, and other contaminants are removed here.
The Wasserwerk Hosterwitz was expanded between 2015 and 2020. A large pumping station and three sludge tanks were built. These allow sludge from the Elbe’s bank filtrate to settle. This eliminates the need to interrupt the pre-cleaning of the bank filtrate for sludge disposal. The goal was to increase the maximum daily treatment capacity to 107,000 cubic meters. The control electronics were also relocated to flood-proof transportable containers, and an inner dike was built. The total cost was around 6.4 million euros.
So, as you can see, Wasserwerk Hosterwitz has a rich history. It has evolved to meet Dresden’s changing needs. It remains a vital part of the city’s infrastructure, ensuring a reliable supply of high-quality drinking water.