Hà Nội, on 6 October 2026, became the focal point of a national investigation into why rivers in Việt Nam's biggest cities remain polluted despite an installed base of 83 treatment plants designed for 2.06 million cubic metres a day, with a headline finding that only about 18 per cent of urban wastewater is actually being collected and treated (vietnamnews.vn). The reporting, built around the Tô Lịch, Kim Ngưu and Nhuệ rivers and the HCM City canal system, frames the country's wastewater problem as a collection gap, not a treatment-capacity gap.
Key takeaways
- At the end of 2024, Việt Nam had 83 treatment plants in more than 50 cities with a combined design capacity of 2.06 million m³/day (vietnamnews.vn).
- Plants were receiving about 1.06 million m³/day, just over half of design capacity, because the sewer networks that should feed them are incomplete (vietnamnews.vn).
- By the construction ministry's count, only around 18 per cent of urban wastewater was being collected and treated, a figure re-confirmed by a National Assembly oversight team in 2025 (vietnamnews.vn).
- Hà Nội has approved a basin clean-up expected to cost more than VNĐ75 trillion (US$2.9 billion) between 2026 and 2029, with the city counting about 2,500 pollution sources in the catchment (vietnamnews.vn).
- HCM City is counting on the Nhiêu Lộc–Thị Nghè plant, designed for 480,000 m³/day and due to be finished and test run by 31 December, to push collection above half of wastewater and treatment above a quarter to standard (vietnamnews.vn).
What happened on the Tô Lịch
In August 2025, contractors diverted the Tô Lịch River's sewage outfalls to a new treatment plant at Yên Xá; lake water and treated effluent were fed in to keep it flowing, and the river took on a mossy green rarely seen on its surface (vietnamnews.vn). When the supplementary lake water was switched off, stretches of the Tô Lịch turned dark again and the smell returned, because, in the words of a Tô Lịch project management board representative, "rain and sewage still share the same pipes in the area, so a downpour can send a mix of both spilling into the river" (vietnamnews.vn).
Trần Hoài Anh, deputy director of the construction ministry's Department of Construction Infrastructure, said in late 2025 that about 70 per cent of wastewater in areas that have sewers is collected, but many mid-sized and smaller cities have no central collection or treatment system at all, so household sewage runs into storm drains (vietnamnews.vn). Nguyễn Việt Anh, vice president of the Vietnam Water Supply and Sewerage Association, told the outlet that a simple flow-balance check — water supplied to a neighbourhood against flow arriving at the pumping station — should show 90–100 per cent capture, yet the national estimate has stuck at around 18 per cent (vietnamnews.vn).
What it means beyond Hà Nội
Along the Kim Ngưu River, a 60-year-old riverside security guard, Nguyễn Văn Hiếu, said the water is dark and reeks of sewage, particularly on muggy days, but clears when heavy rain flushes the system (vietnamnews.vn). Farther southwest on the Nhuệ River, 54-year-old drinks vendor Bùi Xuân Hòa told the outlet that raw sewage is regularly dumped straight into the water, including a three-day episode just before Lunar New Year 2025 that she said produced an overwhelming stench (vietnamnews.vn). In HCM City, the renovated Nhiêu Lộc–Thị Nghè canal was still drawing complaints of discoloured, foul-smelling water earlier this year, with rubbish from upstream piling up at its lower end (vietnamnews.vn). The reporting also referenced the wider public-health backdrop in which untreated discharge has proved fatal elsewhere, with coverage of the 1999 death of eight-year-old Heather Preen after she contracted E. coli O157 on a Devon beach near a combined sewage outlet (The Guardian).
Specification read
Restating the reported scale in buyer units: 83 plants at a combined 2.06 million m³/day (2,060 MLD) of design capacity versus roughly 1.06 million m³/day (1,060 MLD) actually received, with 18 per cent of urban wastewater collected and treated nationally. Hà Nội alone is sizing a basin programme that the report values at more than US$2.9 billion over 2026–2029, and HCM City's Nhiêu Lộc–Thị Nghè plant at 480,000 m³/day (480 MLD) is the single largest asset moving to completion by the end of this year.
The class of project implied here is a combined-sewer-area interceptor feeding a large urban secondary works: coarse and fine screening, grit removal, primary clarification, biological treatment in an A2O, MBR, MBBR, SBR or UASB configuration sized to a high population equivalent, followed by tertiary filtration and disinfection before discharge. The stage this event bears on is the front end — collection, interceptor and pumping — not the bioreactor, because the bottleneck is that only 18 per cent of urban flow is reaching the headworks. If your plant is one of those running at 50–60 per cent of design capacity because its interceptor sewers are incomplete, with BOD and COD in the typical combined-sewer range and a regulator pushing for higher capture, the procurement focus shifts from new tankage to upstream gravity and pumped networks, pumping-station flow metering, and disinfection capacity to handle the wet-weather surges that currently bypass the works.
Buyers mapping this opportunity should treat it as a collection-and-interceptor programme first and a municipal treatment upgrade second; for the smaller cities that the report says have no central system at all, the appropriate product class is packaged integrated sewage treatment with on-site disinfection equipment. The wider context of untreated discharge and beach-water fatalities is covered in our related piece on rural sewage treatment in Qatar and in the broader industrial wastewater management buyer's guide.
FAQ
How big is the Việt Nam urban wastewater gap in m³/day?
The construction ministry's end-2024 count is 83 plants designed for 2.06 million m³/day, actually receiving about 1.06 million m³/day, with only around 18 per cent of urban wastewater collected and treated (vietnamnews.vn).
What is the headline contract value and timeframe for Hà Nội's clean-up?
More than VNĐ75 trillion (US$2.9 billion) between 2026 and 2029, against about 2,500 pollution sources the city has logged in the basin (vietnamnews.vn).
Which single plant is closest to commissioning and at what capacity?
The Nhiêu Lộc–Thị Nghè wastewater plant in HCM City, designed for 480,000 m³/day and due to be finished and test run by 31 December, with collection targeted above half of wastewater and treatment above a quarter to standard (vietnamnews.vn).
How do operators tell whether sewage is actually reaching a plant?
Nguyễn Việt Anh of the Vietnam Water Supply and Sewerage Association recommends comparing water supplied to a neighbourhood against flow at the feeding pumping station; setting aside rain and groundwater infiltration, the pumping-station figure should be 90–100 per cent of supply, but the national estimate remains around 18 per cent (vietnamnews.vn).
