Brazil is known for having the largest potable water reserves in the world. According to the World Atlas (“Which Country Has The Most Fresh Water?“), in 2014, the country had about 8,200 km³, almost double the amount available in Russia (second place). However, since mid-2014 several regions of Brazil have been devastated by water shortages in dry seasons, what used to be a more latent reality in the northeast of the country is now a constant concern also of major economic and political centers such as Sao Paulo and Brasilia. The periods of lack that the country has gone through have caught the attention of international information vehicles, such as The Economist (Water in Brazil – Nor any drop to drink | The Americas), The Guardian ( Brazil’s worst drought in history prompts protests and blackouts) and World Bank ( Brazil may be the Owner of 20% of the World’s Water Supply but it is still Very Thirsty).

Jacareí River Dam Reservoir, Part of the Cantareira System (The Guardian, 2015).

Knowing that water is an essential resource for human life and for various sectors of the economy, several alternatives have been explored in order to make up for the lack of quality water in the country’s rivers and springs. An excellent alternative, easy to replicate, and that allows the best use of this natural resource is the Rainwater Harvesting system or Cisterns. According to the Water Treatment Website (Rainwater harvesting generates savings of up to 55%; see your roof potential), rainwater harvesting systems can generate savings of up to 55% in water supply costs. Rainwater reuse solutions have been gaining national relevance in recent years, being the object of national incentive policies, such as the law 13.501/2017, which stimulates the creation of state and municipal laws on the subject.

Operation and Benefits of the System

Faced with the context of scarcity and climate change, the NGO Engineers Without Borders has developed and implemented rainwater reuse systems consisting of low-cost reservoirs used to capture, store and conserve rainwater that flows through roofs and gutters, thus ensuring the reuse of this water in a more direct and economical way. PVC pipes are connected to the gutter outlets, directing the water collected by the roof of the building to a filter, which aims to remove large materials such as leaves, branches and solid waste present on the roofs. The first rainwater eventually contains particulate waste, such as dust and sediment, and is then directed to the disposal device. When the initial volume collected is discarded, the water is directed to storage tanks. The tank has also an overflow pipe that allows the disposal of the excess volume, and a turbulence reducing device, which aims to reduce the whirlwind and proliferation of organisms.

Rainwater Harvesting System Sketch Implanted by ESF (ESF, 2019).

The water collected by the cistern is of good quality and can be used for non-potable purposes such as cleaning, gardening, irrigation, and even for use as a toilet flush.

Despite the filtering process, the system is not recommended for drinking use because it does not have adequate treatment or disinfection for this purpose. Thus, rainwater harvesting is an alternative for schools, community centers, houses, and buildings for collective use to save drinking water from the city’s sanitation system. The cost of the project varies according to the storage capacity, type of reservoir, and length of the piping. However, if alternative materials are used such as handcrafted bombones and filters (EverlastinglySustainable), the total cost of implementation may be less than R$ 500.00, which makes the solution accessible and economically affordable.

The main benefits generated by this system, when installed, are: it incorporates environmental education concepts in the community where it is inserted; it is easy to install and low-cost; it helps combat the water crisis; it reduces the demand of the water resource for water treatment; it allows savings of up to 55% in the value of the water bill monthly; it prevents the proliferation of the Aedes aegypti mosquito and helps combat floods.

Rainwater harvesting system implemented by ESF-SP (ESF, 2019).
Work of Engineers Without Borders

Knowing all the advantages mentioned above and with the objective of minimizing the effect of the water crisis in the country, the Engenheiros Sem Fronteiras network carries out rainwater harvesting projects in all regions of Brazil, starting at Engenheiros Sem Fronteiras – Viçosa, in the first half of 2017. The city of Minas Gerais, as well as much of the southeast region, faced several consequences due to the lack of water in the two previous years. Since then, the project has been carried out by several centers, either to generate water savings, reduce costs, or bring a more sustainable alternative to the location. Knowing that water is a fundamental human right for everyone and that access to it is aligned with the Sustainable Development Objectives of the UN and Engineers Without Borders – Brazil, we believe that rainwater harvesting systems have much to contribute to the rational use of water and sustainability in the place where it is installed.

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The rainwater harvesting project, besides being sustainable, also has a high degree of replication, without the need of specialized labor and making use of low-cost materials. The cisterns can be installed in practically any place that has a basic structure of collection (roofs and gutters) and a place to house the cistern. Based on the projects already executed, the project time (from planning to execution) lasts on average about 3 months, and may vary according to the implementation site, system sizing, capital collection, planning and other external factors. In order to keep costs, deadlines and quality within plan, Engineers Without Borders uses project management methodologies based on PMBOK (PMI) and PMDPro (APMG International).

The project is divided into the stages of planning, choice and preparation of the site to be implemented, elaboration of the ground plan, collection of capital for the purchase of materials, execution and installation of the rainwater harvesting system, and education for society (aiming to improve its conservation and environmental awareness).

The execution consists in the installation of the piping and cistern that, together, transport and store water collected by the rainwater drainage system (roof and gutters). Auxiliary devices are installed along the piping, such as filter and disposal tank. The filter is intended to retain leaves, branches, insects and other solid materials that are carried by rainwater. The “first rainwater” is collected by the disposal tank and must be rejected due to the large amount of impurities not retained by the filter, such as dust, sediment and animal feces. After filling up the disposal, the water is then sent to the cistern, where it is stored for later use. Finally, it is necessary to add chlorine or sanitary water, which works as a disinfectant agent avoiding the proliferation of microorganisms and mosquitoes.

Education for society is the final stage of the project’s implementation and its main objective is to make the population aware of the importance and need to save water, in addition to explaining the functioning of the system and transmitting guidelines for periodic maintenance. This stage has special importance, since Engineers Without Borders values the engagement with society, always being concerned with involving society during the planning, execution and post-project, improving the understanding by the beneficiaries and working on important aspects such as education and sustainability.

It is believed that the rainwater harvesting project is an excellent alternative in several aspects, bringing environmental and educational benefits to the localities where it is inserted. Considering the low technical level required for its implementation can become an excellent option not only for those who suffer from the water crisis in times of drought, but also who seek financial savings in water consumption or even make their communities more sustainable.

Below we have projects executed by some Chapters of the Organization:


Victória Abrahão
Anna Beatriz Bergo
Mariana Gomes
Vitor Rodrigues