More than half the rivers in India are polluted, with the developing economic power unlikely to meet demand for fresh water from its still-growing population unless dramatic measures are taken, a new report by government scientists has found.

The number of rivers defined as “polluted” in India has more than doubled in the last five years, from 121 to 275, an assessment by the central pollution control board (CPCB) says.

A primary cause is the quantity of sewage generated by cities and towns along polluted stretches the CPCB’s report found.

“In view of population increase, demand for freshwater for all uses will be unmanageable,” it said.

The survey, reported by the local Mail Today newspaper, will add to the pressure on the Indian government to act to protect the environment in the country of 1.2 billion.

On Monday, Narendra Modi, the prime minister, blamed the changing lifestyles that have come with India’s 25 years of rapid economic development for rising pollution levels that have given the country some of the world’s dirtiest air.

A survey released last year by the World Health Organisation (WHO) found that Delhi, the Indian capital, was the most polluted city on the planet, with an annual average of 153 micrograms of the most dangerous small particulates, known as PM2.5, per cubic metre.

The level was six times the WHO’s recommended maximum, 12 times US standards and more than twice the level considered safe by Indian authorities. In all, 13 of the world’s 20 most-polluted cities were in India, according to the WHO.

The country’s waterways have also suffered badly in recent years, with vast quantities of municipal and industrial waste discharged into them every day.

Modi has made cleaning the Ganges, the major river that is holy to Hindus, a key policy goal. There has been little progress so far on a project which has defeated successive administrations, despite substantial funding.

Ministers have said they consider clean air to be a “birthright”.

Speaking at the launch of a new national air quality monitoring index, Modi also urged Indians to curtail waste and conserve resources even as they become wealthier, in order to prevent an environmental catastrophe.

“Until we focus on our lifestyle and get the world to focus on it, we will not succeed despite all other measures being taken,” Modi told state environment ministers in Delhi.

“It is difficult to convince the developed nations about this,” he added, saying that India should set an example.

“We have given a perception to rest of the world as if we are not bothered about climate and environment. The world is tackling with the challenge of global warming, but they still haven’t been able to find a way. No one can question India’s sensitivity towards nature protection,” Modi said, and called on his compatriots to pledge that “once a week we will not use any kind of products that use any kind of energy”.

India is under pressure to disclose its plans to cut green house gas emissions before UN talks from 30 November to 11 December in Paris.

Delhi has so far balked at committing itself to major cuts, arguing that it will not set itself targets that undermine efforts to end poverty.

China announced its plan to cap its emissions by about 2030 in a joint announcement with the US last November.

Experts have previously criticised Delhi’s readings as erratic and unreliable, calling for more transparency and rigour in the data. Much of India’s air pollution comes from coal-fired power plants, crop burning, domestic cooking with firewood or cow dung, and vehicles burning diesel fuel.

Black carbon, which constitutes most of the PM2.5 that can lodge and fester in human lungs, is also blamed for up to 20% of global warming.