Highly filtered treated sewage might find its way back down to the aquifer in a few years’ time if a project piloted by the Water Services Corporation works out.

“We’ve been hearing a lot about the aquifer being depleted and we’re trying to help in bucking that trend,” Marc Muscat, the corporation’s chief executive officer said. The corporation plans to reclaim all the water possible from treated sewage.

At present, the corporation has a small purification plant at the Bulebel Industrial Estate, above a reservoir which was built in the 1980s to accompany the Sant’Antnin Sewage Treatment Plant in nearby Marsascala.

The plant, which was transferred to Malta from Ras il-Ħobż in Gozo, takes the second class water treated at the Marsascala plant and runs it through an ultra filtration unit, which removes the large impurities in the water. It is then run through a reverse osmosis plant. At the moment, the corporation is running purity tests on the water being produced, which is currently being pumped back into the sewers.

The water will only be injected into the aquifer through boreholes after the Malta Resources Authority establishes that it is safe. It would be passed through further barriers – the porous rock leading down to the aquifer, taking a long time to seep through, which would also rid it of any viruses there might have been.

If the pilot project works out, the plan is for the Ċumnija, Mellieħa, Ras il-Ħobż, Gozo and the Ta’ Barkat plant outside Xgħajra to start recharging the aquifer with reclaimed water, Mr Muscat said.

Currently, sewage treatment plants are dumping treated effluent directly into the sea.

“The idea behind this project is to further treat this water to make it usable,” said Tonio Muscat, an engineer working on the project.

“In other European countries, water is discharged into lakes and rivers, which are also used as potable water sources. In Malta, however, we do not have the luxury of rivers and lakes, and at the same time we have an aquifer which is being depleted. The water is being treated more than is normally done in other countries, as we cannot afford to make a mistake in a sensitive area such as Malta’s aquifer, which caters for the whole island,” the engineer said.

One of the conditions laid down by the MRA for the recharging of the aquifer to take place is that the water being pumped into it would be of a better quality than the one already present, as otherwise the water would be contaminating the aquifer, rather than improving it.

All this comes at a cost, however. The infrastructure to make this happen once the new sewage treatment plants are operative, which can potentially pump back 60,000 cubic metres daily into the aquifer, is expected to cost €28 million, and the water reclaimed would come at a cost of 54c per cubic metre.

The plan, however, is for the project to be sustainable even in the financial sense, and the CEO pointed out that the MRA is already in the process of metering boreholes, implying that businesses which are extracting groundwater might have to pay for the privilege to do so.