Malta is one of the most water-stressed countries within the EU. Its potable water is a blend of desalinated seawater and groundwater sources. This blend is continuously monitored to ensure that its quality is compliant with the EU Drinking-Water Directive 98/83/EC. One of the major requirements of this Directive is that the potable water supplied to the consumers is safe for their health. Consequently, the disinfection of drinking water is paramount to safeguard public health.

A common method of disinfection is through the application of chlorine, or chlorination. In Malta, chlorination has been the adopted process to render distributed potable water safe for several decades. To this day, this method of disinfection is used by the Water Services Corporation as its main safeguard towards a safe potable water supply. Over the past years, the use of such disinfectant in the production and distribution of drinking-water has provided satisfactory results for both primary and secondary disinfection. The use of chlorine for such purposes is effective and at the doses required for disinfection, it is safe for public health. Having said that, unfortunately, even when used in doses as low as 1.0 mg/l, and sometimes even lower, the residual amount of chlorine is easily detected in form of taste and odour. This causes the water to be perceived as having a low quality. Another disadvantage that lies with the use of chlorine is the formation of by-products which may also cause an adverse effect on the quality and sensory properties of the water.

Project PURILMA is being undertaken by the Water Services Corporation in partnership with the University of Malta (Department of Food Science and Nutrition). It seeks to identify innovative technologies suitable for disinfecting the water produced in Malta at the primary stages while also establishing the best way to continue making use of chlorine in relatively much lower quantities. This will be done with the aim of improving the taste and odour of the potable water supplied by the Water Services Corporation thereby increasing the consumers’ acceptability of the public water supply. This will in turn benefit the environment as the consumers would opt to use tap water for their drinking requirements rather than purchasing plastic water bottles, thus decreasing plastic waste.

Throughout this project, three disinfection technologies will be short-listed and studied at bench-level. During bench testing, the UM’s team will be able to determine each technologies’ capability in disinfecting water effectively and up to the standards defined by the Drinking-Water Directive. Similarly, their potential to form avoidable by-products and in turn, their sensory manipulation on the water will be established. It is envisaged that this research will give a clear indication of a potential disinfection technology to be included in the Water Services Corporation’s drinking-water production line. Eventually, the technology showing the most promising results during bench-testing will be further assessed on a pilot-scale level by the Water Services Corporation. This arrangement will allow the Corporation to ensure that upon using this disinfection technology on a national level, the public health will be safeguarded and the taste and odour of tap water will be improved, accepted by all and at no additional cost.

Project PURILMA is financed by the Energy and Water Agency under the National Strategy for Research and Innovation in Energy and Water (2021-2030