If you are planning to drive through the North-bound Sta Venera tunnel, do not do so in an open-top car. Water has again started pouring from a section of the roof.

The leak appeared to have stopped over the past few weeks, but returned with a vengeance yesterday after two days of rainfall, although the source is still under investigation.

On September 29, the tunnel was closed for two hours after water started pouring from the ceiling. The following day, with no intervention from the Water Services Corporation, the leak stopped abruptly, only to start again in December and then stop again.

The WSC and Transport Malta last month said they had carried out tests to establish where the water was coming from, but the results were inconclusive.

Chemical tests by the WSC established that the water leaking into the tunnel was “considerably different” from that in the mains or drainage pipes running in the area and even differed from two private boreholes nearby; one near the Fleur-de-Lys roundabout and another one in Triq Antonio Miruzzi. The WSC said it could be “contaminated rain water that is somehow finding its way through fissures above the tunnel”.

Meanwhile, a spokesman for the transport authority, which is responsible for the tunnel, had said tests carried out on water culverts showed the fluid was not coming from there either.

The transport regulator ruled out that the fissures could be a threat to the tunnel. “Transport Malta has engaged the services of a structural engineer to assess and closely monitor the structural stability of the tunnel. The fissures are not a threat to the structural integrity and stability of the tunnel.”

In October, a spokesman for the WSC had said that if the source of the leak was not identified by the end of October, the authorities would consider attaching a water catchment system to divert the leak to drainage channels running along the tunnel’s sides.