Oaxaca 2016: Rainwater Harvesting

Author: Kevin Zhou      Photo Credit: Gabrielle Weiss

On our second day in Oaxaca, we were fortunate to have an INSO staff member, Vincent Aba, introduce us to the Intelligent Water Use Program (PIA). PIA is one solution to solve the shortage and cost of water for users in the city of Oaxaca de Juárez. Water problems in the city of Oaxaca are due to many factors. One is that the city’s water pipes and infrastructure are old, dating from the early 20th century and the pipes leak! This means that about 50% or more of the city’s piped water supply is wasted. In addition, everyone from hotels to households receives water just twice a week to fill up their tanks. Therefore, the city relies on water trucks run by private companies to deliver water. And for many, having to buy water is an economic hardship that builds injustice into the water supply and price. Poor people use more of their household income when they buy water and rich people tend to pay less. In addition, water trucks are not consistently available in some of the poorer neighborhoods.

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One solution to provide some of the water needed by households and businesses is to capture rainwater. The technique and practice of rainwater harvesting is an old one in Oaxaca. For hundreds of years, convents and monasteries used their roofs to capture rain and store it in large cisterns. The current rainwater capture system promoted by INSO is a 21st century re-invention to this older method of rainwater harvesting. Water harvested during the rainy season (starts in June and ends in November) can be used for washing clothes, showers, toilets and watering the garden.

Rainwater capture is very efficient in Oaxaca during the rainy season, as most precipitation comes in major rain events. People only need to put a rainwater collecting system on their rooftop to benefit from using rainwater. By adjusting the gutter and pipeline, rainwater will be led to a filtered container underground, or in people’s backyard. Rainwater harvesting can be a game changer in the current water system. It only relies on the weather and it is a green infrastructure that can help the current situation in Oaxaca.

We walked with Vincent from the INSO office back our eco hostel, Casa Angel Youth Hostel, to see the rainwater harvesting system they owners installed with technical help from INSO. As the picture 2 shows, the blackboard is the lead for rainwater to entire a pipeline network connected to a “first-flush filter,” (essentially trapping the initial runoff contaminated by dirt, debris, etc) before endnig in the facility´s cistern. But, these dirty water and wastes are not wasted. They will be used for watering the garden. Vincent is working with other hotels and hostels that are large water users to help the idea of rainwater harvesting. Promoting this type of green infrastructure is one step in making water use more sustainable in Oaxaca.

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