Prawet district officials have discovered water being leaked out of sewers into road tunnel where a businesswoman was drowned in her pickup truck trapped in the flooded tunnel in Prawet district on Wednesday night.

The officials found the leaks after all the water was pumped out of the tunnel on Friday.

Prawet district police superintendent Pol Col Alongkorn Sirisongkram has ruled out the assumption that a malfunctioned water pump caused water to flow into the road tunnel –one of the two routes leading to Golden Nagara housing estate.

However, he said police would question more people in order to be able to determine correctly who should be held accountable for the flooding of the road tunnel.

Prawet district chief Thanasith Methpanmuang, meanwhile, said that the tunnel was under water of between 70-80 cm deep on normal days, but on the day of the tragic incident, there were 1,970 cubic metres of water as the water was reported to be about three metres deep.

He said Bangkok Governor Aswin Kwanmuang noted that the incident should serve a valuable lesson for precautionary measures to be taken to avoid a repeat of the tragedy.

The governor has suggested CCTV and rescue equipment to be installed at all road tunnels, he added.