Microorganisms in swimming pool water can pose a serious health threat and pool disinfection is therefore compulsory by law in all developed countries. The most common disinfectant is chlorine, which is always found in its active form, hypochlorous acid (HOCl), in pool water. HOCl is rapidly decomposed by UV light, losing its bactericide effect, and a continuous supply is needed to maintain safe levels of microorganisms in pool water.Cyanuric acid (CYA) stabilises HOCl and is added to pool water to slow down the degradation of HOCl. CYA does not degrade however, and the CYA concentration therefore rises steadily over time. At high CYA levels, chlorine is overstablised, rendering it ineffective as a disinfectant. This increases the risk of recreational water illnesses (RWIs) and acceptable levels of CYA are therefore regulated by law. Currently the only viable solution to this problem is to replace some of the pool water with fresh water, which poses environmental concerns due to the large consumption of water this implies. The effects of high CYA levels also have a negative effect on the image of the swimming pool facility and can lead to a loss of business. There is therefore a strong need to find a way to break down CYA in pool water.POOLSAFE will provide an effective and efficient solution to the CYA problem through the development of a soft sensor to monitor the levels of CYA and other pool water quality parameters, as well as a simple, cost-effective method for degrading excess CYA, using photocatalysis. With its two-fold method of ensuring that CYA never reach a hazardous level, POOLSAFE will reduce the environmental impact of swimming pool maintenance by eliminating the need to periodically replace the pool water, provide improved safety to bathers by ensuring that chlorine lock and the subsequent lack of sanitation is prevented, and ensure compliance with health and safety regulations for pool water.