• Christelle Kwizera

Increasing Rain Water Harvesting

"On one side people are complaining of empty tanks, on another side streets are flooded and gutters overflowing, and all the residue from runoffs ends up in rivers polluting them to the point where purification becomes very expensive for the water treatment plants that bring water to the city. It was a three-side sided problem, a self-feeding cycle we found a win-win situation to" - Christelle Kwizera on the creation of the project.

While countries like Germany see 2/3 of new buildings equipped with rain water harvesting (RWH), most Kigali households do not harvest and use their rain water despite a building code requirement to do so. In this article we dive deeper into the water sector, why solutions like are needed and what can be done to fast-track adoption.

The water sector is underfunded

There is a need to improve the ability of countries to provide drinking water to their population. According to the 2021 UN SDGs Report, despite some progress, more than 2 billion people still lack safe drinking water and 1.7 billion don´t have access to basic sanitation. This is primarily due to the degradation of water resources across the globe, as shown by heavy rain sediments, water pollution from agricultural chemicals, fertilizers, industrial residue and municipal waste.

This issue is getting worse in regions with already high water scarcity and water stress levels, like Sub-Saharan Africa, where more than 386 million people do not have the basic access to water and where current investment in the water sector are not enough to achieve Sustainable Development Goal 6 of “Water and sanitation for all” by 2030.

According to Wambui Gichuri, the Acting Vice President of the Agriculture, Human and Social Development Complex at the African Development Bank Group, the annual investment necessary to reach this goal in sub-Saharan Africa has been estimated to be $35 billion per year. Current investments are only $4 billion per year. That is a $31 billion/year gap, and it grows wider every year.

The added costs of not attending this issue is much higher than the needed investment. A partial estimate of the global economic losses caused by water insecurity include the following:

· $260 billion per year from inadequate water supply and sanitation.

· $120 billion per year from urban property flood damages.

· $ 94 billion per year of water insecurity to existing irrigation schemes.

Currently, countries like Rwanda are facing an interesting challenge: finding new ways to adapt themselves to the current environmental conditions, expected and experienced climate change impacts, while supplying their population with clean and safe water.

For this, water harvesting seems to be ahighly successful and accepted strategy. It can reduce losses from increased rainfalls while unlocking water access for millions.

Water harvesting in Rwanda

Countries like Rwanda are investing heavily in rainwater harvesting (RWH) technology in order to supplement their water needs as the situation continues to aggravate. Since 1970, the country has experienced a 1.4°C increase which is considerably higher than the global average of 1.1°C. The Green Climate Fund estimates that by 2050, the temperature in the region will increase up to 2.2°C and the average annual rainfall will increase by up to 20%.

Furthermore, seasonal droughts and intense rainfalls, erosion and floodings will become much more common, and will threaten the livelihood of farmers, particularly those without the economic means to obtain water during harsh dry seasons. Conservative estimates show that Rwanda´s yearly losses will equate to around 1% of the country´s GDP by 2030.

This vulnerability of local communities to environmental changes can be addressed with localized strategies to harvest rainwater during the intense rainy season months of the year, as well as restore and maintain other water sources, like underground reservoirs. This is the opportunity that Water Access Rwanda is creating. is born

At Water Access Rwanda, we are committed to empowering people by providing them with cheap access to safe drinking water. We are able to achieve this with several initiatives such as INUMA: which has supplied over 135 Million liters of drinking water at an average $1/1,000L price, and specifically launched in 2020 to fast-track adoption of rain water harvesting technologies and increase usage of rain water for those who already harvest and use it. offers full rainwater harvesting and treatment systems (rain to tap) that currently allow for 117m3/hr of purified water to reach 18,400 people in households, schools, and restaurants to satisfy their water needs. This has allowed our household users to save an average of 61% of their water bills (when compared with tap water purchases before) while the water expenses for schools were reduced by 71% for a total of $33,000 between January and October 2022. The savings are bigger when you account for prior purchases of bottled water or other treatment mechanisms households used to employ to purify their water.

Through, we provide both the treatment system as well as professional installation services in Rwanda, and the cities of Bukavu and Goma, in the easter side of the Democratic Republic of the Congo.

The rain to tap system starts from the rooftop, where often safe rain water is contaminated with whatever dirt was on the roof. Through a correctly sized First Flush Diverter (FFD), the rain water from the roof is safely harvested into a tank after all unwanted sediments and roof dirt is diverted into the FFD. From the tank, the water undergoes a 4 stage filtration process which will remove unwanted pollutants from the water before it is consumed.

Our 4-Stage Water filters work through the following mechanisms:

1. Polypropylene Sediment Filter (PP): A PP filter is used to remove sand, dirt, sediment, and non-dissolved particulates bigger than 5 microns from the water.

2. Granulated Activated Carbon (GAC): Proven option to remove certain chemicals like pesticides, industrial solvents and volatile organic compounds (VOCs) from water. Furthermore, they also eliminate any particles that give water unwanted odor and taste, like hydrogen sulfide or chlorine. In manganese/iron heavy source waters, this filter can be replaced with one containing Activated Manganese Sand.

3. Carbon Block Filter: Removes remaining hardness and smaller chemicals like hydrogen sulfide and nitrates.

4. UV light: Kills of up to 99.99% of remaining bacteria and viruses that are present in the water.

With this technology, we are able to provide completely safe drinking water for all the people who use our products.

Recently, Rwanda Standards Board put our filter to the test. Feeding it raw water with more than 100 cfu/ml (colony-forming units) of e.Coli, our filter removed 100% of the contaminants for a purified water with >1cfu/ml (less than one is another word for too little to count or absent).

But making a great product is not enough. Working through the existing funding gap, we must find ways to mobilize available and existing actors to own and use that product.

We enable individuals and communities to acquire our equipment through financing and a flexible payment model where individusls access the system and pay in 12-months and 6-months installments. In the first half of 2022, we were able to finance 37 new installations, allowing households to pay on a comfortable 12-month plan with average monthly payments around $45. This allowed our users to afford our equipment while also reducing their expenses. We also continued to sell our most affordable filter for $50, with monthly payments of $8 over 6-months.

Still, this unlocks it for some users while leaving out many more. That is why we partnered with the Rwanda Water Resources Board, through their Enterprise Partnership Initiative, on a pilot project to offer subsidies of 25% and 50% to users who would harvest more water. The result were tangible, with some households who owned our system upgrading their water harvesting capacity from 3,000L to 13,000L in one case.

It is not enough

However, our efforts are not enough to attend everyone. The COVID-19 pandemic and the subsequent economic recovery slowed down our expected growth. This is replicated across the world, with limited investment and support. Without additional funding, we won´t be able to provide everyone with fresh drinking water and sanitation by 2030.

How can we achieve this? By doing the following:

  • We will continue developing the technology, especially with a view of bringing costs down. We have already improved it quite a bit with an FFD sizing tool which means technicians take measurements, size and install the system on the spot within the day. We have the capacity to install up to 5 systems per day as a result.

  • We are experimenting with increasing payment plans to 24 months. We previously extended from 6-months to 12-months plans with great results.

  • We need meaningful subsidies for both companies, households, especially schools to allow them to afford the necessary equipment. With more people harvesting and using their rain water, we increase water accessibility, safety and most importantly reduce run-offs.

We see ourselves as pioneers, who have already proven the viability of this concept, adding a new layer of certainty on the actual usage of rain water. Prior, several subsidies in the sector resulted in many people buying tanks but many found the tanks only useful to store piped water as the rain harvesting committed critical purification equipment.

With our pilot, we can confidently demonstrate to users (especially households and schools), real monetary savings and increased water safety with our equipment. This creates more buy-in from users, while also reducing run-offs since tanks do not remain full during the rain season.

We need to invest in infrastructure that will allow people to adapt themselves to the changing environment. Particularly, for countries like Rwanda, we need to encourage governments and businesses, as well as everyone else, to work together to increase adoption and usage of Rain water harvesting (RWH). There are already successful examples for Rain Water Harvesting adoption:

  • In Germany, there has been significant promotion of RWH systems at the local level through the implementation of subsidies up to a 50% of the total cost of installation, materials and civil work up to a certain limit. Currently, more than two thirds of new buildings have RWH systems installed in them.

  • In Indian states of Gwalior and Jabalpur, builders get a 6% tax rebate when they add a RWH system. In the Surat Municipal Corporation has made RWH mandatory for new buildings and provides up to a 50% subsidy to citizens.

Together, we can make a difference, but only by working together, and doing it now. Otherwise, the damage to the environment will be irreversible.

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