Solvatten is a dual water treatment and solar water heating system that is tackling climate change
and improving lives in Kenya’s urban slums. The device harnesses the power of the sun to
treat and heat water, reducing the need to heat and boil water by burning firewood or charcoal. The
units are capable of rendering highly contaminated water drinkable in a few hours, provided there
is sufficient sunlight. Solvatten Solar Safe Water Heater improves health, increases renewable
energy, reduces deforestation, addresses climate change and gives access to safe water, while
lifting people out of poverty.
2,592 Solvatten systems have been distributed and sold at a subsidized price in Kenya,
benefitting 12,900 people in Nairobi’s urban slums
22,000 tonnes of greenhouse gas emissions have been avoided in Nairobi’s urban slums
after four years of Solvatten use
Almost 62 million litres of water have been treated since 2012
More than 40,000 Solvatten systems are used daily by more than 200,000 people around the world
Families in Sub-Saharan Africa typically heat and boil their water by burning firewood and charcoal. Not
only is this time consuming and expensive, it causes harmful indoor air pollution and releases greenhouse
gas emissions. The high dependence on firewood and charcoal by a large percentage of the population is a
major cause of deforestation in Kenya.
Swedish inventor Petra Wadstrom created the Solvatten system to bring portable water treatment and solar
water heating to people in developing countries. Solvatten addresses poverty-related health issues that are
connected to energy scarcity and poor water quality.
By harnessing the energy of the sun, the system ensures that the water is safe to use. A combination of
UV rays and heat warms and eliminates all pathogenic material in 10 litres of water
within 2-3 hours, allowing for multiple batches of water to be treated in a given day. The system is
maintenance free and can be used more than seven years.
Helping the planet
The solar technology reduces the need to heat and boil water by burning firewood or charcoal. This leads to
reduced deforestation, reduced burning of solid fuels, and consequently reduced emissions, as well as
reduced fuel expenses for the urban poor. One year of using a Solvatten unit saves 5-6 mid-size trees.
By using solar energy instead of charcoal to heat and purify water, the Solvatten project in the Kenyan
urban slum saves up to 6,000 tonnes of CO2 emissions every year. After four years of Solvatten use, 22,000
tonnes of greenhouse gas emissions have been avoided.
The significance of efficiency
Energy efficiency is the most effective tool to reduce energy sector emissions and contribute to limiting
global warming to less than 2 degrees centigrade. The Solvatten technology makes resource use more
efficient and provides the technology needed to refine that resource for use. In this case, the Solvatten
technology purifies and heats water, directly improving energy and water efficiency.
Considering the efficiency factors, Solvatten should be valued not only based on the services that it
brings, but also on the savings and ease of use that it entails. Moreover, even if there is infrastructure
for water and energy available, Solvatten can support an under-sized electrical grid and water
By ensuring access to safe and heated water the technology has increased the urban poor’s resilience
to the effects of climate change, such as droughts and floods, and reduced their vulnerability to
water-borne diseases. Both droughts and floods reduce water quality, which facilitates the transmission of
In this case, the Solvatten units were distributed and sold at a subsidized price of USD 15 for the
end-user, generating a profit of USD 3 for the seller. The Nordic Climate Facility subsidized the units at
a cost of 66% of the total market value, reducing the up-front burden. Use of Solvatten significantly
reduces the amount of money the urban poor spends on alternative fuel sources (wood or charcoal). On
average, users have been able to reduce their energy costs by half (savings of 11-12 USD per month).
Solvatten increases safety for women and girls by freeing up time for chores, such as collecting water and
wood for cooking and boiling that typically fall on women and girls. Solvatten enables women and girls to
focus on productive activities and school. According to a Solvatten survey, 66% of respondents said that
absenteeism from school and jobs was significantly reduced after the inception of Solvatten.
Solvatten aims to make health, environmental and economic benefits accessible to as many people as
possible. The technology is available for the UN system, NGOs, governments and others to insure that
families have a tool that brings heated and safe water to improve daily life. Solvatten contributes to
reaching all of the 17 Sustainable Development Goals. Solvatten is exploring the possibility of scaling up
the project to expand not only in Nairobi’s slums but in other parts of Kenya too. The goal is to
reach millions of people living without access to electricity and safe water.
More than 800 million households worldwide currently use solid fuels. For these households living in sunny
conditions, CO2 emissions could be reduced by 1 tonne per year if they reduced heating/boiling with solid
fuels by using Solvatten.
Solvatten is highly replicable as the project methodology and process are successful and sound and can be
replicated to other cities in other countries.
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