MEXICO CITY, Apr 5 2021 (IPS) - In neighbourhoods like Tehuixtitla in southern Mexico City, rain brings joy, because it provides water for showering, washing dishes and clothes, and cooking, by means of rainwater harvesting systems (RHS). Water storage containers are part of the landscape in the streets of Tehuixtitla. Residents keep them next to their homes to supplement their water supply by buying water from tanker trucks.
“When it starts to rain, we feel so happy. We clean and sweep so that there is no dust on the roof and gutters, and so the water doesn’t get dirty or clogged,” said Gabino Martínez, a resident of Tehuixtitla, part of the touristy municipality of Xochimilco, one of the 16 districts that make up Mexico City.
This is what the 63-year-old man told IPS, pointing to the roof of his house to show the infrastructure that makes it possible to collect rainwater to meet the family’s basic needs for part of the year.
Martínez, a married father of three who works as a handyman, still has a little water left from last November’s rains, and is counting the weeks until May brings the first drops, provided the climate crisis doesn’t modify the normal seasonal rainfall.
Gabino Martínez cleans the "Tláloc", the tank that filters dust from the rainwater collection system in his home in the Tehuixtitla neighborhood in the Xochimilco district in southern Mexico City. During the May to November rainy season local residents collect the water they use for washing, bathing and cooking, due to the lack of access to piped water. CREDIT: Emilio Godoy/IPS
“We don’t waste water here. Everything we store, we use,” said Martínez, who installed his system in 2008 at a cost of about 270 dollars and whose neighbourhood was the first in Xochimilco to have RHS, since the public water supply system does not reach this area nestled between hills.
Before rainwater began to be harvested, the people of Tehuixtitla, who today number some 2,500 spread over 11 streets, collected rainwater with makeshift systems and filtered it through cotton cloths. They also bought water from tanker trucks, known locally as pipas, which they then carried in jerry cans to their homes.
“Utilities” was just an abstract term in the dictionary. But through community organising, they have obtained electricity, telephone and internet services, essential for working and studying during the COVID pandemic.
The RHS consists of a receptacle, called “Tlaloc” because of its physical resemblance to the Aztec rain god, which filters dust out of the water before it runs into a 5,000 litre tank, to be distributed to the local supply network. The collectors allow two or three downpours to pass through first so the harvested water is cleaner.
Rain is the salvation
Rainwater can help this Latin American country of 126 million people face the water crisis which experts project will start in 2030, while it currently causes floods and landslides and generally ends up in the drainage system.
Rainwater harvesting reduces the need to obtain or import water from conventional sources, allows the creation of supply at specific points and does not depend on the traditional system.
At the same time, it can help Mexico achieve the goal of clean water and sanitation for the entire population, the sixth of the 17 Sustainable Development Goals (SDGs) set for 2030.
The situation in greater Mexico City, home to more than 21 million people, is particularly delicate, as the metropolis is heading towards the so-called “Day Zero”, when it will no longer have enough water to meet its needs.
The city is the third most water-stressed of Mexico’s 33 administrative divisions, after the states of Baja California Sur, an arid territory in the extreme northwest of the country, and Guanajuato, located in the center-north and strained by agricultural activities.
Purchasing jerry cans of water transported by donkey is the alternative left to the inhabitants of Tehuixtitla and other neighbourhoods in the hills of the Xoxhimilco district, in the south of Mexico City, when the rainwater collected during the rainy season runs out and the supply of water from tanker trucks, locally known as “pipas”, is delayed. CREDIT: Emilio Godoy/IPS
Drought is raging this year in Mexico, especially in the capital, whose main source of water – the Lerma-Cutzamala dam and reservoir system in the neighbouring state of Mexico – is below half its capacity.
As a result, the local government has had to ration water in a city already under pressure from shortages.
In Mexico City, the largest metropolis in Latin America, some 15,000 people suffer from poor access to water and marginalisation, in eight municipalities in the south and southeast of the city, according to the 2019 study “Captación de lluvia en la CDMX: Un análisis de las desigualdades espaciales” (Rain catchment in Mexico City: An analysis of spatial inequalities), the latest edition published.
In addition, approximately 70 percent of the city’s residents have water available for less than 12 hours a day.
Government programmes have been operating in Mexico City since 2016 to provide RHS to neighbourhoods affected by a lack of water.
The “Rainwater Harvesting Systems in Mexico City Homes” programme, which in 2020 gave families about 900 dollars in subsidies, has installed more than 20,000 devices since 2018 in five municipalities on the outskirts of the city to the south and southeast.
By 2021, it will reach 529 neighbourhoods in eight municipalities in the capital. However, the programme only includes homes in urban areas. Households in shantytowns outside the city are considered to be located on land earmarked for conservation, and the classification of these neighbourhoods as occupying public land means they are denied services.
Mexico City’s constitution, in force since 2017, stipulates that the city will “guarantee universal water coverage and daily, continuous, equitable and sustainable access” and that it will incentivise rainwater harvesting.
But on the hills of the southern municipality of Tlalpan, for example, that constitutional article has not been enforced. That is why, for residents like Silvia Ávila, RHS systems have been the salvation.
“The situation was very difficult, we had no water. It was a big problem. The authorities at the time sent a tanker truck once a month, but we had to walk about a kilometre and pipe the water to our homes using hoses,” she told IPS during a visit to her house.
“It wasn’t enough water even for our basic needs. There were people who didn’t even have a water tank to store water. This was a desert because of the lack of water and services,” she said, explaining the transformation that RHS has meant for families in the neighbourhood.
With the installation of a 10,000-litre system in 2011, for which she paid about 230 dollars, much more than her access to water changed.
“When it rains, we can meet our basic needs,” said Ávila, a widowed homemaker and mother of four. “Every house has a system. It has allowed many to live off their own crops. We have become sustainable, little by little. After arriving here, the programme was expanded to several nearby towns.”
Paraje Quiltepec resembles an ecovillage. Its 30 families use biodigesters, make vermicompost, recycle water, raise chickens and grow fruits and vegetables.
In the dry season, neighbourhoods like Tehuixtitla and Paraje Quiltepec buy tanker truckloads of between 6,000 and 10,000 litres for 50 dollars per household. In the former, the local government also helps, distributing 800 litres a week.
Not only Mexico City suffers from water shortages
The Mexican capital reflects the water problems in this vast country with an area of 1.96 million square kilometres, 67 percent of which is arid and semi-arid and 33 percent of which is humid.
In 2020, Mexico received more than 722 millimetres of rainfall per day, below the average of 779 in recent years.
Although Mexico had a low degree of pressure in 2017 – 19.5 percent – its risk of water stress is high, according to the Aqueduct platform, developed by the Aqueduct Alliance, made up of governments, companies and foundations.
In fact, it is the second most water-stressed country in the Americas, behind Chile. It may suffer from water stress in 2040 all the way from the center to the north.
Enrique Lomnitz, founder of the civil association Isla Urbana, a pioneer in rainwater harvesting that installed the systems in Tehuixtitla and Paraje Quiltepec, pointed to the progress made in the last decade with regard to the adoption of rainwater harvesting.
“A market and promotion policies have been developed. Rainwater harvesting relieves some of the demand in an autonomous fashion, reducing pressure on the government to provide the service,” the promoter of the initiative explained to IPS.
“Sometimes water is abundant in this country, but it is seasonal. That is why it is becoming increasingly important to harvest rain, because we cannot afford to waste what falls from the sky,” he said.
Lomnitz noted that downpours increase the availability of water and are the only source of water in several areas of the capital.
Since 2009, Isla Urbana, the winner of several international awards, has installed some 21,000 RHS throughout the country.
The National Programme for Rainwater Harvesting and Ecotechnics in Rural Areas (Procaptar) was launched in 2016, benefiting 4,500 people in 114 municipalities between 2018 and 2020. In 2021, it will help 11,500 inhabitants in 63 municipalities.
The 2019 report estimated that the installation of 105,000 RHS would improve conditions for about 41,500 people.
The 2019 “Internal Evaluation of the Rainwater Harvesting Systems in Mexico City Homes Programme” concluded that the programme met its physical goals in the installation of systems, and reported good acceptance and satisfaction among beneficiaries.
In addition, it recommended improving adoption of the system, especially in maintenance, performance indicators and gender perspective. The 2020 review has not yet been published.
In Tehuixtitla people are not waiting. Local residents are designing a pumping system with the state-owned National Water Commission to provide them with drinking water, at a cost of about 1,750 dollars per household.
“It’ll improve living conditions here,” Martinez said enthusiastically.
Lomnitz suggested creating incentives for rainwater harvesting, reviewing service subsidies and encouraging wastewater treatment and reuse.
“In the city the situation is very serious, so measures are needed to take care of water,” he said. “There is a range of possible solutions, such as recycling water or using water-saving devices. Rainwater harvesting is one of several elements that need to be worked on to address the crisis. But it alone will not solve the problem.”