The city draws some 94 percent of the water it uses for treatment at a spot downstream of where the Saigon meets the Dong Nai River, the Hoa Phu pumping station in its Cu Chi District, and at Hoa An in Dong Nai Province.

But it has become impossible for the city to control the pollution or the saltwater that flows up the river from the sea.

This is not even to mention the fact it has to rely on provinces and cities in the Dong Nai River basin to treat wastewater thoroughly before discharging into the river.

So the city plans to draw water from a spot further upstream in the Saigon River, which originates in Binh Phuoc Province and flows through Tay Ninh and Binh Duong Provinces before meeting the Dong Nai River.

It is around 20 km (12.42 miles) from the Hoa Phu pumping station and reportedly less polluted by domestic, industrial or agricultural wastewater.

The Dong Nai River originates in the Central Highlands and runs south to Dong Nai Province and HCMC, where it meets the Saigon.

According to the city, the water in the Saigon-Dong Nai river system suffers from severe microbiological pollution besides oil and gas from ships.

Pollution indicators like ammonia, microorganisms and manganese have all increased.

Besides, in the dry season saltwater flows well past the point where the city draws water, making it unpotable.

Authorities are also working on a plan to build reservoirs to store water for treating.

On average, each city resident consumes 140 liters of water daily.

By 2025 the city plans to ensure every resident gets tap water and increase the average supply to 165 liters.