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A detailed look at HCMC’s water supply serious problems, 13 million at risk

The city's water security is under threat from an increase in pollutants, a lack of an up-to-date water distribution network, and salt intrusion.

"Oil stain down the river."

"It was the most stressful Sunday in all my 33 years as head of the pumping station," - Woken up by the 6 a.m. announcement and quickly got dressed and headed to the Hoa An pump station, five employees who lived close to the station, alongside the director of Thu Duc water treatment plant were quickly dispatched to the scene, which is around 30 km away from HCMC. 14km away, at another water treatment plant, employees from the plant's water quality management department were also called to take samples and test them for oil.

Since 2009, Saigon Water Corporation (Sawaco) had been preparing for the possibility of a water shortage, but it hadn't actually happened until now. 

Whether an environmental crisis akin to what happened in 2019 may happen again, depends on how quickly this problem is dealt with.

Oil spills can be difficult to clean up, as the oil spreads out and seeps into the surrounding water. The spill in this case was close to two pumps where raw water would be sucked in, and it had already stained the dykes black. People used buoys to block off sections of the spill, but it wasn't enough.

Tran Kim Thach, head of the water quality management department at Sawaco, asked for the raw water to be checked every fifteen minutes in order to ensure that it was safe. Unfortunately, two of three water treatment plants detected oil in their supply. Thach immediately ordered that all water be flushed out of the system in an effort to remove any oil residue. After discharging around 10,000 m3 of water within two hours, the oil was gone thankfully.

Incidents of water contamination are a serious problem for any water supply system, especially in Ho Chi Minh City, which is almost entirely dependent on outside sources for freshwater. There are hundreds of other pollutants that can also harm the environment, and they're often hard to detect.

Dan said that factories and industrial complexes should have been located in downstream areas, like HCMC or Ba Ria-Vung Tau, instead of upstream areas like Binh Duong and Tay Ninh. The pollutants they produce would affect the water downstream.

"HCMC cannot completely manage the water quality on its end," he said, adding that the planning for the construction of industrial complexes should be done depending on regions, not localities.

According to a report by the Ministry of Natural Resources and Environment, wastewater released from daily activities in the Dong Nai River could have reached 4.7 million liter per day by 2020. The amount of wastewater released annually from all sources in this river alone accounts for one-third of all wastewater released nationally. Water quality in the Saigon River, one of Vietnam's most polluted rivers, has been dropping year after year. However:

"The state of the economy and the environment are always inversely proportional to one another"

Saigon and Dong Nai rivers have been an important factor in the Southern Key Economic Zone's growth over the past decade. In 2019, this region provided 5.1 billion cubic meters of water to various plants - 68.3% of all industrial wastewater usage in Vietnam during that year. However, as wastewater levels increase every day, it is becoming increasingly difficult to keep these rivers clean and healthy.

When the environment paid for our prices

"Using fuel comes with a price, and in this case, it’s the environment (that pays it)"

In the seven years from 2014 to 2020, industrial wastewater discharged into rivers has increased by 111%, from 110,000 to 1.21 million cubic meters a day. This increase in wastewater is due in part to an increase in the amount of industrial waste produced, but also an increase in the diversity and complexity of pollutants detected. Over the past decade, pollutants and contaminants have been found in water samples from the Saigon River section running through Binh Duong and HCMC frequently. These substances change the color, taste, and smell of water, as well as causing gastrointestinal symptoms like diarrhea.

The environment ministry has issued regulations requiring water quality be evaluated at various depths every six months and tap water be evaluated every month.

A 2021 survey by the Asian Water Research Center (CARE) found that new pollutants have been detected in the Saigon River and they are not being included in water quality metrics by both the environment ministry and the health ministry. Specifically, CARE found 106 out of 205 known organic micropollutants in samples taken from the river.

The study, conducted by the United States Geological Survey and released last April, found that micropollutants produced through industrial, agricultural and daily activities were present in the water supply in HCMC and its neighbors Tay Ninh and Binh Duong.

"These pollutants may have a negative impact on HCMC's water sources, as they were found near the sites where HCMC gets its raw water." - Professor Nguyen Phuoc Dan of CARE. "I had to send the samples to Sweden for analysis because Vietnam still doesn't have the technology or resources necessary for these tests." The water supply was found to be polluted with micropollutants, which is an indicator that the issue must not be overlooked.

Dan said that factories and industrial complexes should have been placed in downstream areas, like HCMC or Ba Ria-Vung Tau, instead of upstream areas like Binh Duong and Tay Ninh. The pollutants they produce would affect the water downstream.

"HCMC cannot completely manage the water quality on its end,"

Dao Phu Khanh, deputy head of the department of environmental health and school medicine under the HCMC Center for Disease Control, said that stable organic pollutants (SOPs) are one of the most toxic types of pollutants. They can be carcinogenic and hard to get rid of, as well as propagated over large distances and accumulated inside organisms.

Khanh said that he is not familiar with the specific pollutants that are being mentioned, and because they are not included on the water quality evaluation list, there is no way to know if they are safe or not.

"If we do discover the presence of these pollutants in raw water, we would also have to test the quality of tap water to measure their levels, as well as routinely monitor them and evaluate risks. It would be dangerous if tap water has high levels of these substances," he said.

And More Chemicals Doesn't Stop

In HCMC, home to 13 million people, many raw water sources are becoming more unsustainable than ever as the city's 140-year-old water treatment and distribution system cannot keep up with economic growth. When an emergency arises, the city lacks a contingency plan to respond.

"The poorer the raw water quality is, the more chemicals would need to be used,"

The water quality management department at HCMC uses pre-oxidation and coagulation methods to filter its water before it is treated with chlorine to get rid of microorganisms. The filtration system cannot meet more stringent water quality standards, such as those for contaminants such as antibiotics or organic micropollutants. Even with current technology, treating water contaminated with salt would be difficult.

The amount of chemicals used for water treatment in Ho Chi Minh City has consistently exceeded government standards over the past seven years. For example, the amount of lime used for water filtration is around 10-13 times the current threshold, the amount of chlorine around 1.8-2.6 times, and the amount of polyaluminum chloride three times higher than what is recommended by Ministry of Construction guidelines. Despite the fact that HCMC's water quality meets health ministry standards, it is considered too "ancient" and lacks proper water treatment systems, which can lead to many risks.

For example, if the ammonium level in the water gets too high and chlorine is still used to treat it, toxic substances like nitrites or nitrates could be produced, causing numerous symptoms if ingested. Water problems in HCMC are not limited to the water treatment system. They also extend to how HCMC distributes its water throughout the city.

Contaminated tap water

In 2014, HCMC experienced a water crisis when the health ministry discovered that three of the city's largest water treatment plants did not meet quality standards. This meant that tap water in certain areas of western HCMC was contaminated with several diarrhoea-causing bacteria species.

An investigation found that high water pressure in certain areas near the treatment plants led to sediment buildup, which caused problems with hydraulic flow. This higher water pressure was especially pronounced in downstream areas, where it was much lower than in surrounding areas. Sediments like iron and manganese can attach themselves to pipes when there's a surge of water, and when this happens during a hydraulic disturbance (like an earthquake), the sediments are swept along with the flow of water.

Another potential issue with this water treatment method is that the speed at which water flows through the pipes can be inconsistent. If the water moves too slowly, it allows chlorine to evaporate and, as a result, there is not enough chlorine in it to kill germs.

The water distribution network in HCMC is outdated and needs to be updated. It is 8,200 km long, and many parts of it are in poor condition.

Thach said there are two types of water distribution networks: ring-like networks, which have a main pipe and several reservoirs to supply water to smaller branches, and fishbone-like networks, which have one main pipe and several smaller branches. Ring-shaped networks are more efficient when it comes to dealing with sediment buildup because the consistent pressure from the pipes keeps debris at bay. Fishbone-shaped networks might be more efficient when it comes to cutting off water supply in certain regions due to sediment build up but would find it difficult if necessary deal with situations where regular water pressure is not maintained.

"The city’s water supply network was built in the French colonial times (1880s),"

A ring-shaped water network, which HCMC's water network is, would have interconnected pipes as part of a common network, making it easier to deal with water supply cuts. However, due to inconsistent water pressure, there would be more sediment buildup in the system.

Salt intrusion, the unlikely culprit

Tran Duy Khang, the director of Tan Hiep water treatment plant, said that salt intrusion has been a problem that has haunted his dreams since he had to deal with a salt intrusion crisis in 2016.

"We’ve never had to face such a dangerous situation. The pump station was forced to stop taking in raw water,"

The water at the Hoa Phu pump station had a salinity level of over 300 mg/l for around four hours during the 2016 crisis. This was higher than any previous salinity level ever seen and allowed the pump station to hold its ground until more freshwater came in from Dau Tieng Lake to dilute it. However, during the 2016 crisis, Dau Tieng Lake was only at 76 percent of its maximum capacity, meaning that not enough water was available for use.

Khang's phone rang constantly for those four hours, with the only treatment plant that could provide water for residential networks in the western parts of the city being Kenh Dong. If Khang allowed valves to be opened to let the Thu Duc plant supply water, it would have weak water pressure and sediment would accumulate.

After considering all of the options, Khang decided to compromise and only drink water from the Kenh Dong plant while waiting for salinity levels to fall.

Following the incident with the Tan Hiep plant, the tension never left the Hoa Phu pump station. The pump station had to stop taking in raw water 15 different times between January and March due to high salinity levels.

Ho Chi Minh City's biggest predicaments

HCMC has two major water-supply facilities: the Thu Duc plant in the west, which receives water from the Dong Nai River; and the Tan Hiep plant in the east, which receives water from Saigon River. The east side of HCMC has had a stable water supply regimen for many years, while west side suffers from two predicaments at once: river pollution and salt intrusion.

The dry season is a time of great anxiety for 800,000 families living in 11 districts in the west of the city, which account for around 36 percent of all families. When it comes to closing down Tan Hiep, announcements from the factory are often few and far between - leaving people wondering whether they will have to wait until next year or longer.

The 2016 water crisis has forced the Tan Hiep plant to make changes to its salt intrusion prevention processes. The plant has extended a contract worth 4 billion VND ($171,210) a year to make sure that the Dau Tieng Lake will be ready to discharge water whenever needed. Three water reservoirs were also built in order to store water for 6-7 hours if raw water could not be taken from rivers for some reason.

Nagging worries

According to a 2021 climate change report by the Intergovernmental Panel on Climate Change, the amount of rainfall on the Dong Nai River is projected to rise towards the end of the century. This would mean an increase in water levels, exacerbating risks of salt intrusion. Several experts have warned this could lead to more coastal flooding and erosion.

The freshwater pump stations downstream from salt intrusion suffer the most from the contamination. If salt is not removed, no water can be taken in, so these stations would have to stop operating until the salinity is gone.

The uneven distribution of water throughout the year means that HCMC will continue to worry about water shortages.

"HCMC’s worries for the future aren't exactly a lack of water, but the fact that there would be too much water without a way to deal with it,"

- Dao Nguyen Khoi, head of the environment department of the HCMC University of Science.

In a worst-case scenario, the Saigon Dong Nai river area would be impacted by both droughts and salt intrusion during dry seasons, said Khoi. The three pump stations--Hoa Phu, Binh An, and the newly built one at Cu Chi--would be unable to operate because of salinity levels that are too high.

"The water supply may increase, but if the quality can't keep up, it will be of no use,"

Water pollution, treatment systems that lag behind, and salt intrusion exacerbated by climate change are the most dangerous threats to HCMC's water security. As the economy grows and the population keeps rising, there will be more wastewater to deal with.

We Need To Act Now

Source: VNExpress