At our university, both the indoor and outdoor swimming pools are disinfected using salt electrolysis, a modern and sustainable technique. A small amount of salt is added to the pool water. This salt (sodium chloride, NaCl) is then converted into chlorine (sodium hypochlorite) using a low electrical voltage. The chlorine works directly as a disinfectant. This method ensures stable water quality and provides a pleasant swimming experience for everyone who regularly takes a dip.
Water quality and reliability
Salt electrolysis provides a continuous supply of freshly produced chlorine, keeping disinfection levels highly stable. Because the chlorine is generated directly within the system and does not age during storage or transport, the water quality remains consistent. In addition, the swimming experience is milder, as fewer by-products such as chloramines are formed. Swimmers often experience the water as fresher, with less odor and reduced irritation of the eyes and skin. You won't taste any salt, by the way. Salt electrolysis automatically produces exactly the amount of chlorine needed at any given moment. This greatly reduces the risk of peaks or drops in chlorine levels, improving both safety and hygiene. The result is predictable, stable, and safe water treatment.
More environmentally friendly and safer
This technique is demonstrably more environmentally friendly than traditional methods. The required salt is easy to store and has a low environmental impact. By producing chlorine on site, packaging waste is avoided and energy-intensive transport is no longer necessary. Controlled production also results in less chemical waste and fewer harmful by-products. All of this makes salt electrolysis a more sustainable solution, perfectly aligned with the sustainability ambitions of our university.
Solar collectors
Did you know that a total of forty solar disks and five solar collectors have been installed across the roofs of the changing rooms, on top of the existing boiler system, and on the rooftop terrace? Together, in 2025, they generated 26,276 kWh of electricity and 15 GJ of heat. This means the swimming pool not only contributes to sustainable energy generation but also produces part of its own energy demand. This energy is used to heat both the outdoor pool and the water for the nearby showers. This is beneficial for the environment and helps reduce energy costs.
The sustainable heating system supports the extensive and intensive use of the swimming pools. The pools (Sports & Culture) are used by swimming, water polo, and diving associations for training sessions and competitions. The outdoor pool also serves as the setting for various sports events, including the annual UT Triathlon and the Kick-In pool party. Special events, such as the spectacular 2025 edition of Ter Land, Ter Zee en in de Lucht, have also taken place here. In addition, the UT Swimming School provides weekly swimming lessons for children in the indoor pool. Thanks to the solar collectors, the use of the outdoor pool is becoming more sustainable.
And did you know that on our Energy Data Platform (Energy Data University of Twente) you can see exactly how much energy the different buildings use? This gives everyone insight into current consumption and trends throughout the year.
