Post-Legionella at the swimming baths: SCHELL SWS and SCHELL shower panels help to maintain drinking water hygiene

5-minute read

After the discovery of Legionella in the showers, the Rheinmünster swimming baths were temporary taken out of service. The clean-up project that followed took just six months – using sustainable solutions from SCHELL.

Managers of public and semi-public sanitary facilities must always be aware of the risk of Legionella and apply the principle that ‘prevention is better than the cure’. In the Rheinmünster swimming baths, a routine inspection discovered Legionella in the female and male showers. Urgent action had to be taken, especially since the swimming baths were also used by local schools who had no other venue available for their swimming lessons.

Climate change comes home to roost

The Rheinmünster swimming baths opened in 1976. The mixing station for the shower water still housed in the basement also dates from this period. To date, this mixing station was responsible for heating both potable and non-potable water for the showers in the swimming baths and the adjacent sports hall to 40 °C, and then pumping it upwards. When water was left in the piping overnight, however, this provided an ideal breeding ground for Legionella. This problem was made worse by the over-dimensioned and corroded piping, also dating from the 70s, which promoted its spread, as well as low pressure in several sections of piping. Hydraulic balancing was necessary in order to maintain a minimum flow speed throughout the installation. The cold water mains presented another problem. Here, climate change was to blame: the temperature at the point where the utility line entered the building was reaching 20 °C during warmer weather – the typical 80 cm depth used here (to protect against frost) was no longer deep enough to keep the drinking water cool. Accordingly, fresh water had to be pumped regularly into the building mains, so as to flush out stagnating water and effectively prevent bacterial propagation.

Shower panels with integrated thermostats

As a first step, all of the over-dimensioned piping in the basement was replaced and almost the entire installation ‘slimmed down’ – reduced from DN 125 to DN 50. The outdated mixed water installation was replaced by a new and more advanced system that now produces hot water at 60 °C. In addition, water is now routed to the showers by two drinking water lines for cold water and hot water. The old concealed shower fittings were also dismantled, being replaced by 17 electronic Linus D-C-T exposed shower panels instead. These enhance the overall visual appeal of the shower area while improving comfort for users and are very easy to service. The integrated thermostat was the main reason for choosing to install these shower panels: hot and cold water can now be mixed to an agreeable temperature in the shower panel itself instead of in the basement. This short route from heating to actual usage by visitors to the baths hugely reduces the risk of Legionella.

SCHELL’s SWS Water Management System – safety first

Where corners certainly can’t be cut when it comes to maintaining drinking water quality: regular stagnation flushes. This is why the showers in the Rheinmünster swimming baths are now flushed automatically. The automated flush simulates specified normal operation, ensures a complete exchange of water and also logs all of the flushing operations. A second solenoid valve in the shower panel also offers the option of conducting thermal disinfections with hot water at 70 °C to kill off any potential bacterial contamination. The central control and documentation (logging) of stagnation flushes and thermal disinfections is handled by the SCHELL SWS Water Management System. Here, all of the flush times have been set as specified by the planning engineers, with multiple shower panels arranged into flush groups. Thanks to SCHELL SWS, the individual piping segments and shower fittings can now be flushed at a high volume flow rate without intervention from facility staff, which greatly reduces the risk of biofilm formation and Legionella growth in the piping.

Planned with an eye to the future

The wired variant of SCHELL SWS was installed in the Rheinmünster swimming baths: bus cables were run between the individual sanitary facilities and each of the 17 shower panels was connected up. Data is transmitted through the cables, and can be analysed (and the parameters adjusted) at any time. This means maintenance work can be planned well in advance. The system is very easy to operate, since the SWS software is browser-based and can be accessed from any standard PC, tablet or smartphone. This cost-effective, expandable and updatable system not only simplifies maintenance and servicing but also meets requirements for maintaining drinking water hygiene both today and in the future. Especially since renovations to the potable and non-potable water installations here in Rheinmünster are just the first step. All of the technical systems, together with parts of the building envelope, have yet to be renovated here at the baths. As part of this work, additional electronic SCHELL fittings on wash basins, WCs and urinals can then also be integrated – wired or wirelessly – into the existing network. At the moment, only SCHELL offers this option of combining wired and wireless in a single water management system, thereby offering the key to the hygienically safe and economical operation of drinking water installations.