epa-efeMexico City

Ten percent of the Mexican population does not have access to safe drinking water, the National Autonomous University of Mexico's Social Research Institute says in a report issued Friday on the occasion of World Water Day.

Between 12.5 million and 15 million Mexicans are without a secure, reliable supply of water, lead researcher Manuel Perlo said in a statement accompanying the study.

The shortage of drinking water mainly affects rural areas, but it is also a problem for low-income, marginalized neighborhoods in Mexico's major cities.

"Those people suffer from health and hygiene problems linked to lack of water. We have a debt to them," Perlo said.

And even among people who have access to running water, roughly 30 percent of them experience deficiencies in quantity and quality.

"The right to water is in our legislation, but it is not fulfilled," Perlo said.

An amendment establishing access to water as a human right was added to Mexico's constitution in 2012, and Congress was supposed to draft and approve within 365 a General Water Law to make the measure effective, but the legislation has yet to materialize.

Water resources are distributed unevenly across Mexico, Perlo said.

"Most are in the south-southeast, but in the center and north, where the largest part of the population and the economy are located, there is less," he said.

He also pointed out that more than 15 percent of Mexico's 653 aquifers are overexploited.

Aquifers are underground reserves of water extracted through wells and pumping systems that penetrate anywhere from 50m (164ft) to 300m below the surface.

"But much more water is extracted than can be captured naturally, and the number of overexploited aquifers has increased in recent years," Perlo said.

The number of aquifers classified as overexploited soared from 32 in 1975 to 105 last year.

To address the problem, Perlo recommends making water re-use official policy.

Mexico currently treats only half of the water used by households and businesses and that proportion should be boosted to 90 percent, he said.

And at least of 40 percent of the water pumped by utilities is lost to leaks.

Average daily consumption of water per person in Mexico is 322 liters (85 gallons).

Harvesting rainwater could be a good solution for some elements of the population.

In places where there are public parks, rainwater can be captured. These spaces should not only depend on the water they receive from the general distribution system," Perlo said.