MEXICO CITY, Oct. 30 (UPI) -- Millions of central Mexican residents face a weeklong water outage starting Wednesday.
The public water system's engineers say the outage is necessary to undertake major refurbishment of the reservoir pipelines feeding the metropolitan area from the Cutzamala reservoir, one of the world's 10 largest freshwater delivery systems. Pumping stations also require upgrading, as does the electrical supply and the purification system.
"Normally one talks about the metropolitan area, not just Mexico City, and the reason is the water comes from Cutzamala," said Cecilia Tortajada, senior research fellow at the Lee Kuan Yew School of Public Policy in Singapore who is an international authority on public water systems.
The metropolitan area, with more than 20 million people, draws from two sources of water, an aquifer and the reservoir.
"The amount of water taken from the aquifer should be reduced," Tortajada told UPI, "because of the risk it presents to infrastructure and places in the city that are subsiding. The aquifer is not being replenished so the metropolitan area depends on the Cutzamala reservoir system."
The metropolitan area encompasses Mexico City, and the states of Mexico and Hidalgo. About 900,000 people in Mexico City face a total water shutoff and millions more will have water 70 percent of the time, totaling almost 4 million people. The outage also affects 3 million residents in Mexico state, the suburban-rural feeder for Mexico City. The engineering work is expected to end Sunday night, with a return to partial supply on Monday. The public utility services for Mexico City and the state of Mexico have also said it might take until Nov. 8 to restore full water service.
"Everybody should learn from Mexico City's water system for what should not be done," Tortajada said.
Researchers at the National Autonomous University in Mexico City estimate that 35 percent of the water supplied to the city and the surrounding Mexico state is lost in leaks in pipes damaged by earthquakes, subsidence or age.
Tortajada, who used to live in Mexico, worries about the health of the water system.
"It is a system that is very resilient in that it is a system that keeps working in spite of being not maintained properly for decades," she said.
"In this sense, the city is very lucky because it is still working. But it has not been improved for many years and because it is old and so many pipes have been added there are few people now who know physically how the system actually is. There are designs, of course, but it is the old engineers who actually know and I'm not sure that their knowledge at an institutional level has been passed from one generation to the other."
Mexico City has gone from a city of houses to one of apartment buildings, with no corresponding transformation of the water delivery system, Tortajada said.
"You still have the same pipes with the same diameter, which still get the same cubic meters per second. But now, instead of supplying a family in a house, the pipe supplies water to a building constructed where the house was and these can be 10 stories tall. So the people who live at the top never have enough water pressure."
Tortajada said this week's work will not fix the problem of a system that is outdated for the uses its sustains.
"The network of pipes is very big. It's not just the reservoir system that's the problem, and many of these pipes are broken. What we need is a holistic approach," Tortajada said.
On Twitter, some residents are hailing the upcoming outage as the "mega shut-off."
Friday is an unofficial public holiday in Mexico, with many capital residents traditionally leaving for a long weekend to visit family for Day of the Dead. Those who stay behind in the city on long weekends have become somewhat accustomed to water outages.
"It feels like a forced holiday to me," said Irasema Mendoza, a working mother of two kindergarteners. "Schools including child care facilities are closing on Wednesday and won't reopen until the beginning of next week. But the thing is, my employers are not giving me Wednesday and Thursday off, so I don't know what to do with the children."
The outage is technically necessary, she said, adding that many people don't have cisterns to store water during outages.
"It's good to have this awareness about how much we use water," she said. "Maybe it will make people like my husband think more about how much water they use."
To prepare for the imminent stoppage, Mexico City's mayor said the city will deploy more than 900 water trucks to deliver free water to affected neighborhoods. Delivery priority will be given to hospitals and prisons. Child care facilities in Mexico City run by the Mexican Social Security Institute will also close until Monday. The capital's major universities, totaling hundreds of thousands of students, faculty and support staff, will also close on Wednesday and reopen Monday. The closures are necessary to preserve water for hospitals and prisons, water utility authorities say.
Between Christmas 2017 and New Year's Day 2018, the city's residents also faced an unannounced weeklong water outage while engineers conducted repairs to the Cutzamala reservoir.
"This time around it is a little different because there has been more advanced notice," Tortajada said.
Authorities have told city residents to store water in their homes, to take short showers and to use stored water for flushing toilets.