1All information regarding costs and potential savings are estimates based on calculations using the shower calculator provided by the Consumer Advice Centre of North Rhine-Westphalia, as of 4 May 2026 (https://www.verbraucherzentrale.nrw/duschrechner). The potential savings are therefore estimates based on the use of a water-saving shower head with a flow rate of 8 litres or 6 litres per minute, compared to a shower head with a flow rate of 16 litres per minute. The flow rate figures always refer to a water pressure of 3 bar. The term ‘family’ refers to a family of four, which has approximately four times the consumption of a single person. The underlying cost examples are shown in the text. The data on drinking water and wastewater charges stored in the NRW Consumer Advice Centre’s shower calculator are based on statistical data from destatis.de and refer to the year 2022. Current drinking water and wastewater charges may differ from the 2022 figures. The price of natural gas has been set at 10 cents per kilowatt-hour. Actual consumption figures, costs and savings may vary depending on many factors, such as the efficiency of the heating system, the outside temperature, water pressure, the flow rate of the shower head used, individual showering habits and individual costs for water and energy.