The city is running low on water, both above and below ground. A poor monsoon so far has left reservoirs with 48% less water than they held at this time last year, while groundwater levels are about 45% deeper.Metrowater is looking to the sky for relief. “If we don’t get more rain, we might have to consider rationalising water supply, while relying on desalination plants,” an official said.The city’s five principal reservoirs, Poondi, Cholavaram, Red Hills, Chembarambakkam and Kannankottai-Thervoy Kandigai, held 4.79 thousand million cubic feet (tmcft) on Thursday, compared with 10tmcft on the same day last year. That is 41% of their combined capacity of 11.75tmcft.Groundwater levels also dipped. The average depth rose from 3.77m in Oct 2025 to 5.48m in Oct this year, a fall of 1.71m, or 45%. Madhavaram recorded the sharpest fall, from 5.80m to 10.81m. However, levels across city has improved by nearly a metre from last month.Metrowater says desalination will cushion the shortfall. On Wednesday, the 110 million litres a day (mld) and 150mld plants supplied 100mld and 87mld, respectively. By Thursday, the supply rose to more than 100mld in both plants. “Both the Nemmelli plants can be operated at full capacity. By Feb, the Minjur plant, which has a 100mld capacity, will yield at least 20mld,” a senior official said. “We are confident of handling the situation,” he said.Water experts are not so optimistic. They warn that the situation is worrying and the offered solution is dangerous. “Surplus rain was expected this year. But that has not been the case,” said S Janakarajan, a retired professor at Madras Institute of Development Studies. Evaporation from the soil and water lost through plants, together called evapotranspiration, would be very high in summer.Janakarajan said the state govt lacked a water security plan despite several warnings about El Niño. “Chennai receives an average of 120cm of rainfall every year. Desalination plants can never be solution. Govt is taking an easy way out, which harms coastal ecosystem,” he said.Sekhar Raghavan, Chennai’s ‘Rain Man’ and founder of The Rain Centre, an NGO, said residents should not wait for govt to supply water. They should recharge groundwater themselves. “By this time, Chennai should have had at least 140cm of rainfall, but we received only 110cm as of Nov 10,” he said.The govt must act on two fronts. “First, appoint third-party monitors for rainwater harvesting. In many places, builders have not constructed the systems properly, yet the CMDA approved them,” he said. TVK govt relaunched its rainwater-harvesting initiative. “But enforcement will not improve without outside monitors,” he said.“Second, govt must draw up a preventive plan, and it must involve experts with decades of experience,” he said. “The govt must change its attitude and seek external expertise.”“Both floods and droughts are man-made,” he said. “If govts do not learn from experience, the same problems will recur, and we will keep having the same discussions with no change.”