Salt intrusion ruins tap water sources in Mekong Delta

One afternoon in mid-February, Dang Thi Hong Lac, 59, poured out the family’s tap water to test its salinity level. It was 2.2/1,000, much higher than the usual standard of 0.5/1,000.

"This water cannot be used for cooking, but can still be used for showering and laundry. When the salinity level reaches 3-4/1,000, I will use the water stored in the canal, as I worry that the salt-contaminated water would ruin the washing machine and the water heater," Lac said.

After the historic salt intrusion and drought period five years prior, she has built seven reservoirs to store freshwater, enough to cook for the whole family for the entire dry season.

Over a kilometer away, due to the family’s tap water source being contaminated with salt, Nguyen Thanh Mong depends on freshwater stored inside a reservoir for cooking.

Mong and his wife have three children and own a sole 1.5 m3 cement pond. Thanks to benefactors, last year the family got two additional reservoirs made of plastic, capable of storing 1.5 m3 of water.

"The stored freshwater can help us last around three months. If the salt intrusion lasts longer than that, we might have to get water from the commune’s water provision spots," said Mong, 42, adding that there were freshwater provision services in the local area at a price of VND100,000 ($4.08) a cubic meter. A unit of salt-contaminated water meanwhile costs only VND8,000.

Nguyen Huu Hieu, chairman of the Luong Phu Commune People’s Committee, said there are over 1,400 families using tap water in the area, accounting for 80% of the families in the area. Among them, around 500 families live near severely salt-intruded river areas.

There is a water factory in the commune, with a capacity of 90 m3 per hour. But because the water is taken from salt-intruded rivers and streams, their salinity level is at 1.1-2.2/1,000. To meet people’s freshwater demand, the factory has invested in a saltwater filtration system, with a capacity of 2.5 m3 of water per hour.

When the salinity level reaches above 0.5/1,000, the factory turns on the filtration system to provide freshwater, three times a week, providing 60 liters for each family at the same price as normal tap water.

The commune also has six locations that provide collected rainwater, with each spot having a reservoir at a capacity of 15 m3, prioritizing families in circumstances so they can use the water during the dry season.

Ben Tre currently has 60 water factories managed by the Department of Construction and the Department of Agriculture and Rural Development. There are also other private water factories. Right now, the factories are taking water directly from salt-intruded rivers, whose salinity levels are at 0.1-0.3/1,000.

Nguyen Xuan Hoa, vice director of the Ben Tre Center for Clean Water and Rural Environmental Sanitation, said the unit currently managed 32 water factories that serve around 98,000 families. After Tet, salinity levels in water factories of Giong Trom and Mo Cay Nam districts have risen, especially during periods of high tides.

"Currently, besides 15,000 families who use water within standard levels, there are around 13,000 families using water with salinity levels above 1/1,000, and the rest of the families are using water with salinity levels below that," Hoa said.

The center has equipped 29 water filtration systems in factories, as well as transporting water from factories in less salt-intruded areas to more salt-intruded locations to alleviate the situation.

The unit also plans to use barges to transport raw water from river systems, which have yet to be contaminated with salt for people’s use.

The Ben Tre Center for Hydro-Meteorological Forecasting said since the beginning of the dry season, the period with the most severe salt intrusion occurred in mid-February, lasting around a week and resulting in salinity levels at 4/1,000, intruding as far as 55 km away from the estuaries.

The most severe salt intrusion period is anticipated to happen in March, with salinity levels at 4/1,000, reaching as far as 70 km away from the estuaries of the Cua Dai, Ham Luong and Co Chien rivers.