Desalinating a cubic metre of seawater costs the government at least four times as much as extracting the same amount from the water table, Minister Austin Gatt said in parliament on Monday.
But in the absence of measures to clamp down on the illegal extraction of ground water, Malta is set to become more reliant on reverse osmosis (RO) plants, which consume vast amounts of electricity.
While the production costs of deriving a cubic metre of water from the water table amounts to €13, it costs the Water Services Corporation €49 to produce the same amount of desalinated water, Gatt said.
In 2007, 44% of the drinking water supply derived from the water table, while 56% derived from reverse osmosis plants. In the same year, 97 million units of electricity were used to produce 16.97 million cubic metres of desalinated water through the osmosis plant.
But due to rampant illegal exploitation of underground water, the water table is increasingly under threat. A report by the Food Agricultural Organisation warns that water bills may have to be doubled if no action is taken to stop ground water extraction.
Since the costs presented to parliament do not include capital and depreciation costs, reverse osmosis water is probably even more expensive than €49 per cubic metre.
RO comes at a high capital cost due to expensive high-pressure seawater pumps, energy recovery devices and membranes.
The Water Services Corporation also pays a subsidised rate for energy consumed in its reverse osmosis plants. Thus if the WSC was to pay the full price for its energy costs reverse osmosis water would be even more expensive.

jdebono@mediatoday.com.mt