People in Bangkok and its vicinity should save water for household use over the next few days as raw water pumping might be temporarily suspended due to salt water intrusion.
The intrusion has reached the Sam-Lae water pumping station, the biggest tap water producer for the capital.
Narongrit Srisatidnarakul, deputy governor of the Metropolitan Waterworks Authority (MWA), said the salinity level at the Sam-Lae station in Pathum Thani was measured at 0.32 of a gramme per litre, higher than the "monitoring level" of 0.25 grammes per litre.
He said it is possible the salinity will rise above 0.5 of a gramme per litre, in which case the authority will stop pumping raw water to produce tap water as the high levels of salt would damage the water production system. The saltwater enters the Chao Phraya River from the Gulf of Thailand, and ends up at the power station.
"There might be poor tap water levels in Sukhumvit, Phra Khanong, Thung Mahamek, Mahasawat and Samut Prakan province between March 30-April 1. It would be good to reserve some water for consumption," Mr Narongrit said.
The level of salt water increased from 0.16 of a gramme per litre on Monday at the Sam-Lae water pump station to 0.32 on Tuesday. This led to the warning from the MWA for people to conserve water as there are no signs of the salinity decreasing.
Meanwhile, Royal Chitradon, director of the Hydro and Agro Informatics Institute, told the National Science and Technology Development Agency annual conference yesterday he was afraid salt water intrusion this year might might be as bad as in 2014, when a massive amount of water was used to push it back to the sea.
Water flowing at over 100 cubic metres per second from the Chao Phraya dam in Chai Nat was discharged to push back the salty water and the MWA was unable to pump raw water for 70 hours. The highest salinity level was recorded at 1.92 grammes per litre in that year.
The MWA can halt pumping raw water for only four hours without it affecting tap water production. After four hours, tap water can become salty or run dry. However, Mr Royal was confident the 17 million cubic metres per day that is being released by the four major dams in the central region is enough to fight the intrusion problem.