On Block 37, the city water supply starts flowing around 7 a.m. Two or three hours later, it stops.

Evelyn Angeles and her partner make what they can of the window of opportunity, using two taps to fill two 20-liter drums with water to use through the day.

"We can collect enough water to wash our hands, clean our dishes, flush the toilet - and one of us gets to shower," she said, outside her home in Addition Hills, one of Manila's most dangerous and neglected slums.

"It's tough, sure, but it's much worse for people living on other blocks on higher ground," where water pressure is lower, she said, sitting behind a curtain of rubber sandals hanging for sale outside her home.

Since early March, the Manila metropolitan region has been in the grips of a water shortage, as the El Nino phenomenon has contributed to a 60 percet decline in rainfall, compared the country's long-term average, across half the country's provinces in the first part of the year, according to the government.

In Manila, that has exposed shortfalls and delays in the region's water infrastructure.

At the peak of the shortage in March, supply was 30 percent lower than normal in the city's East Zone, according to Manila Water, the private company responsible for providing water to almost seven million people living in the zone.

While commercial centers and heavily touristed areas were largely unaffected, some of the city's more neglected areas had no running water for seven days or more, the company said.

As the crisis mounted, Manila Water's chief operating officer quit, in mid-April.

Before the month was out, the government hit the firm with a $10 million fine for breach of contract and ordered it to spend $12 million developing a new water source.

Water supply has since been partially restored to 98 percent of customers, for at least eight hours a day - though at low pressure, a spokesman told the Thomson Reuters Foundation.

Normal service is expected to resume in June, spokesman Mark Orbos said, when seasonal monsoon rains are expected.

For now, however, life in places like Addition Hills revolves around water rationing.

'A way of life'

The water crisis in Metro Manila - a sprawl of 16 adjoined cities populated by about 12.8 million people - is hardly an anomaly.

From South Africa to India, and across North Africa and the Middle East, water scarcity is creating growing stresses as rising wealth and population growth, combined with climate change, place an unsustainable strain on water reserves.

In Asia, 3.4 billion people could be living in "water stressed areas" by 2050, according to a 2016 Asia Development Bank (ADB) report.

"Water shortage should be treated as a permanent ongoing issue," said Thuy Trang Dang, an urban development and water specialist at the ADB's Southeast Asia office.

Global warming, population growth, diets filled with more water-demanding meat and dairy products and general growth in consumption mean "the issue will only become more pressing unless dealt with not as a one-time crisis but as a way of life", she said.

Metro Manila - the Philippines' capital - is already one of the world's most densely populated urban areas.

The number of people living in the East Zone has ballooned from 3 million to almost 7 million since 1997, when Manila Water was awarded a 25-year contract to supply the zone's water.

During that time, the amount of water the firm has been allowed to draw from the Angat dam has remained steady, at 1,600 megaliters per day, Orbos said.

In 2016, demand began surpassing supply, he said.

"Manila Water has strongly advocated for many years for the development of new water sources ... both to ensure sufficiency of water supply as well as resiliency in case of any calamity," the spokesman said.

"However, the development of the new water source is, under the concession agreement, ultimately the responsibilty of MWSS," he added, referring to the Metropolitan Waterworks and Sewerage System.

Ronald Abrigo, a spokesman for the MWSS, told the Thomson Reuters Foundation that the agency has long sought additional sources of water to shore up Manila's supplies.

Constuction began on a series of new dams and treatment plants in 2017, he said, pointing to a study the Manila government used in preparing its 20-year water security plan.

The study warned that "by 2021, supply would be unable to meet demand" in the capital.

New water?

Faced with a very dry start to the year, 10 provinces in the Philippines had declared a state of calamity as of the start of April, with the Department of Agriculture saying more than $25 million of crops had been lost to drought.

The crisis in Manila hit in early March when the water level at a secondary city source, the La Mesa reserve, fell below the aqueducts that allow it to flow to the city.

When news of shortages spread, people began hoarding water, placing further strain on supply, Orbos said.

In an April 24 statement, the MWSS said it would recommend that President Rodrigo Duterte issue an executive order to fast-track the capital's 20-year water infrastructure plan.

Under the original plan, projects with the capacity to add a total of 1,500 megaliters to the city supply - currently 4,000 megaliters - would go online between 2018 and 2023, when the 600 megaliter Kaliwa dam is scheduled for completion.

The Cardona treatment plant, which was scheduled to begin adding 100 megaliters last year, hit construction delays but will be fully operational by August, Manila Water said.

Meanwhile, in Addition Hills, Aldrin Ricio - who lives a short walk uphill from Angeles - wonders when his water-storing days will end.

The part-time electrician said that most nights he stays awake until 1 am to make the most of the area's delivery schedule for tap water.

Even so, sometimes the water makes it up the hill, and sometimes it doesn't, he said.

"What can we do?" he asked.

"We could complain, sure, but we are the people at the end of the line. We have become used to being the last ones to receive a solution."