In a plan the city administration has put forward for public feedback, the fee will equal 20 percent of the current tap water bills of local households and 30 percent of businesses.

The fee will be applied from this year and rise 5 percent each year until 2023, and the city will only collect it in 12 selected districts out of the total of 27.

Hanoi currently collects an environmental protection fee equivalent to 10 percent of the tap water bill, which averages less than VND10,000 (43 cents) per cubic meter.

However, this sum can only meet 20 percent of what the capital needs to invest in, operate and maintain the city’s drainage system, amounting to millions of dollars each year.

In case the new plan is approved, each household consuming less than 10 cubic meters of tap water per month will have to pay a little more than VND11,000 each month as the wastewater discharge fee; and by 2023, this fee would increase to more than VND22,000.

Hanoi dumps around 1.2 million cubic meters of wastewater per day, 900,000 cubic meters of which is domestic wastewater.

Only 22 percent of the city's wastewater amount is treated, meaning the rest is dumped directly into rivers and lakes, according to statistics from the Hanoi Sewage and Drainage Company.

This carries organic residues, chemicals, heavy metals and microorganisms, polluting the water environment and affecting water companies downstream, driving water quality test levels way below the national standards.

The World Bank said in a report in June that the lack of investment in collecting and treating wastewater was the reason for most of the water problems facing Vietnam.

Polluted water and overdependence on international rivers could drag Vietnam's GDP down by 6 percent annually by 2035, it has warned.