(Photo: WSC)

A third of Malta’ potable water is being produced at the Pembroke Reverse Osmosis plant, with the remaining three plants accounting for another third, and the rest being derived from ground sources.

Figures published in the Water Service Corporation 2024 annual report show that during the period under review water production from RO plants peaked to an all-time high in August at 79,316 cubic metres per day which is roughly the size of 32 olympic swimming pools.  

In total, RO water production in 2024 rose by 8.5% over the previous year, with half of the total production – which stood at 25.7 million cubic metres or 10,200 olympic-sized swimming pools – coming from the Pembroke plant.

The overall annual specific energy consumption averaged 4.68kWh/cubic meter, or just 1.4% more than that of 2023. This increase is the effect of RO membrane ageing, as over time, membranes became fouled, even under normalised conditions, to a point where it would then become cost-effective to have them replaced. In fact, in 2024 a total of 4 RO trains, specifically one at Pembroke, two at Lapsi and one at Ċirkewwa, had their performance restored following the replacement with new membranes. The plan is to continue restoring RO train performance in 2025, with further membrane replacement programmes, particularly at Pembroke.

The increase in population resulted in a bigger demand for potable water with the result that RO plants had to increase production from 22.7 million cubic metres in 2022, to 23.7 million in 2023 and 25.7 million last year.

In 2024, the Pembroke plant produced 51% of all RO production (13 million cubic metres), followed by Ghar Lapsi (30% or 7.7 million), Cirkewwa (11% or 3 million) and the Hondoq plant in Gozo (8% or 2 million). As expected the peak demand is in summer, while the lowest is in January and February.

In its annual report the WSC indicated that by 2030 it would be upgrading generation levels across all plants   and commissioning a new one, to cater for increase in demand.  The total amount of potable water supplied to the whole WSC network for 2024 stood at 38.8 million cubic meters. Potable water production to meet water demand is a mix of reverse osmosis water and ground water production sites.

In 2024, 13.1 million cubic meters, approximately 34% of the potable water production, was met by groundwater. WSC’s strategy to limit groundwater abstraction is complemented by the recommissioning of groundwater sources that had been abandoned, mostly due to collection network limitations. With an improved network to transfer water from production sources to reservoirs, WSC has been reactivating sources whilst reducing abstraction from previously utilised sources. This results in a better distribution of abstraction of groundwater, thus relieving stress on localized water abstraction.