New Delhi | As more than 50 per cent of India's water reservoirs remain dry despite the onset of monsoon, water security must be tackled on both the supply and demand side, an advisor at TERI's water division said.

According to data by the Central Water Commission, 166 major reservoirs across India currently hold 32.38 per cent of their overall capacity, a marginal improvement from last week's 26 per cent.

Speaking about whether India's water storage and demand management initiatives can secure the country's water future amid climate change, Syamal Sarkar, a former IAS officer and advisor at the water division of The Energy and Resources Institute (TERI), said that it is essential to tackle water security from both sides, as demand across the domestic, industrial, and agricultural sectors exceeds supply.

"On supply, storage is key. Major dams currently hold about 250 billion cubic metres, and this can rise substantially through ongoing government initiatives. On demand, the question is how to manage needs when supply falls short, something India, like most countries, has historically neglected in favour of supply-side fixes," Sarkar, who served as a secretary, water resources ministry, told PTI.

According to Sarkar, per capita water availability has fallen from about 5,000 cubic metres in 1950 to roughly 1,500 currently, and that anything below 1,700 cubic metres is classed internationally as "water-stressed" -- a line India has already crossed -- with the country now heading towards the 1,000 cubic metre threshold for "water scarcity." Speaking about the scale of demand, he pointed out that a person needs two to three litres of water a day for drinking, yet Delhi supplies about 165 litres per person per day, with the rest going towards bathing, washing, and other uses largely without being reused or recycled.

He contrasted the data with Israel, which reuses 60 to 70 per cent of its water for agriculture rather than letting it run to the sea.

"NITI Aayog projects that by 2050, India's water demand will be double the available supply," Sarkar told PTI, adding that closing that gap will require both reducing demand through more efficient water management and raising storage beyond current levels.

He attributed the current urgency to climate change, noting that monsoon rainfall has grown erratic in recent years, with no fixed pattern to its timing or volume -- too much brings floods, too little brings drought.

"Without adequate storage, shortages hit growth, drinking water, and even groundwater, which is replenished by surface water," the former IAS officer said.

Sarkar underscored the government responses on the storage front, including Mission Amrit Sarovar, which aims to build 75 water bodies of 10,000 cubic metres each in every district, along with a push for states to adopt rainwater harvesting.

Citing Bermuda, which has no surface drinking water and collects rain from every rooftop into cisterns, he said the model is being encouraged across Indian households and facilities, as only about eight per cent of rainwater is stored, with the rest flowing to the sea.

"Other measures include the Krishi Sanchay Yojana, which encourages community participation with women and girls central to domestic-level storage, along with rainwater harvesting on industrial campuses and more efficient irrigation, where only 30 to 40 per cent of water drawn is currently used effectively," Sarkar said.

Asked what practical steps cities need to take on water infrastructure, given that bursts of heavy rain are making the old approach of waiting for a steady monsoon to fill dams increasingly unreliable, Sushmita Sengupta of the Centre for Science and Environment (CSE) told PTI that cities need to start cleaning up local water bodies, managing wastewater properly, and rebuilding decentralised systems as a sustainable source of water.

She said this is a return to how India managed water long before piped supply took over. The country historically depended on decentralised sources -- small-scale rainwater harvesting, lakes, ponds, and rivers -- with cities traditionally built around a water body specifically to draw from it.

"India depended on rainfall since ancient times, but the British arrival marked a shift toward piped taps," she said.

According to her, the ancestors relied on decentralised systems and cities were built around water bodies. Over time, the British introduced piped drinking water, and households grew used to simply opening a tap that cities adopted and continued ever since.

She noted that the shift itself was not the problem, but the negligence of lakes, ponds, and decentralised water systems, along with the wastewater networks tied to them.

As local water bodies grew polluted and groundwater was over-extracted, she said, cities have had to draw water from progressively farther sources -- Hyderabad from 100-150 km away, Delhi from over 100 km, the Kaveri source from around 90-100 km, and Mumbai from about 95-96 km.

She highlighted that climate change compounds this pattern since erratic rainfall dries up reservoirs and pushes them towards dead storage, while long-distance piped systems lose 40 to 50 per cent of water on average to leakage.

"The result is empty reservoirs with no easy alternative," she told PTI, pointing to depleted groundwater and polluted local sources as the consequence of decades of neglect, until cities begin rebuilding decentralised systems as a sustainable source of water