NAIROBI, Kenya -- It's the rainy season, but the sun is still baking the Mathare Valley slum.
A half-million people live in this warren of shacks clustered amid 10 square kilometers of the Mathare River.
When the rains fall, drops spill like marbles on corrugated metal roofs. Narrow alleys swell with murky runoff that flows past open doors and raises the risk of cholera and dysentery.
When the rains fail, as they did for most of last year, a liter of clean water can cost more than petroleum. People who cannot buy water from traveling vendors haul it from the river or steal it from the municipal main.
About half of Nairobi's 3.2 million residents live in such areas that lack municipal water and sewer services. Beatrice Cheptoo is among Mathare's fortunate.
The 26-year-old mother of two pays 100 Kenyan shillings ($1.30) a month to use a privately built water spigot, shower and toilet. Standing near the freshly mopped "Ikotoilet," Cheptoo points up the slope to a field where goats pick through garbage rotting into rust-colored soil.
"Before, we were used to going and practicing open defecation up there," Cheptoo said, broaching a subject that is taboo for many Kenyans.
The poorest of the poor still relieve themselves in the fetid field, and they use the river to bathe and irrigate tiny plots of vegetables. Water is life -- even in this polluted stretch of the Nairobi River Basin. But what happens when the rivers run dry?
Much of Kenya faced that grim reality last year, during what has been called the deepest drought in living memory. The failed rains, followed by flash floods, exacerbated existing water quality and quantity challenges and forced a fractious federal government to reassess the cost, scale and speed of adapting to a warming world.
Two parts hydrogen, one part oxygen, water is the molecular compound that binds urban sanitation with energy, tourism, agriculture and other sectors throughout sub-Saharan Africa.
"These negative effects of climate change have threatened the economic stability of the country as more resources have been devoted towards meeting the basic needs and life of Kenyans," warned Ministry of Finance Permanent Secretary Joseph Kinyua in a Nairobi speech late last year. He cited a 2009 Stockholm Environment Institute report that estimates $500 million is needed annually to address Kenya's immediate needs as well as prepare the country for future climate change; annual adaptation costs could approach $2 billion in 2030.
When dust turns to mud
Equatorial Kenya's long rains typically begin in March and continue through May. June through September marks a comparatively cool and dry spell before rains recommence in October.
Most of Kenya did not get much rain, if any, until the final weeks of 2009.
"When we have had droughts in the past, there has not been a failure of rains for as long," observed Charles Musyoki, a senior scientist with the Kenya Wildlife Service, which manages nearly 10 percent of the land in this Texas-sized nation.
Tree limbs and watering holes withered, contributing to the death of as many as 500 elephants, according to the wildlife service. Migratory animals and livestock competed for pastures, spurring Maasai shepherds to encroach upon Nairobi's green spaces.
Water levels in important rivers dropped, forcing the Kenya Electricity Generating Co. to reduce hydropower production. Nairobi endured inflated water prices, intermittent blackouts and electricity rationing.
Crops failed throughout the country, even in the breadbasket region between Nairobi and Lake Victoria.
Heavy rains that began in 2010 proved just as problematic.
Flooding in low-lying areas of the Great Rift Valley caused farmland destruction, death, displacement and disease in December and January. By February, an estimated 3.8 million Kenyans needed emergency food assistance -- a 32 percent increase over a year, according to the U.S. Agency for International Development.
Kenya's agricultural sector is beginning to recover with the onset of the long rains this spring, but some southwestern Kenya farmers are abandoning tradition in the face of unpredictability.
"People used to have organized planting and harvesting sessions, but now it is impromptu," said Jacob Olonde, a native of the agricultural hub of Migori. "People plant by trial and error."
Some farmers have switched from planting maize and other food staples to planting hearty bamboo, the 22-year-old student explained.
"They have never done this before," Olonde added.
Roots of a crisis
Experts who study the nexus of population and the environment contend that climate change is only partly to blame for Kenya's water woes.
Historically, East Africa has experienced drought then heavy rains every five to 10 years, caused by a shift in Pacific Ocean winds and currents known as the El Niño-Southern Oscillation. The cycle appears to be getting more frequent and intense, as droughts have occurred during 10 of the past 20 years.
The seasonal shift between wet and dry months is also becoming more volatile, observed Paul Faeth, president of the Global Water Challenge, a coalition of corporations, nonprofits and government agencies that invests in water and sanitation projects in Kenya and other developing countries.
"What you're seeing is an exploding oscillation -- the droughts are deeper and the rainy times are wetter," Faeth explained. "Within that, you are also seeing more bumping around on an annual basis and that just makes things more difficult to manage."
Kenya's mean annual temperature has increased by 1 degree Celsius since 1960, and the number of hot days and nights has increased significantly, according to U.N. data. The changes are consistent with the U.N. Intergovernmental Panel on Climate Change's global warming models, noted Achim Steiner, executive director of the Nairobi-based U.N. Environment Programme.
"We're always cautious about making a causal link, but this fits into all of the models that the IPCC and climate scientists have come up with over the years," Steiner added.
More cautious is Paul Watkiss, a London-based consultant who contributed to the Stockholm Environment Institute's study of the economics of climate change in Kenya.
"Most of the current problems are really due to existing climate variability and socioeconomic change," Watkiss contended in an e-mail.
Such change includes a Kenyan population that has grown more than 20 percent during the past decade to nearly 40 million people.
Of the 150,000 additional housing units needed each year in urban areas, 35,000 are built, according to the government's "Vision 2030" planning document. In rural areas, deforestation, soil erosion and unsustainable farming practices contribute to about $390 million of annual losses, about 3 percent of gross domestic product.
"With every rainfall now, Kenya washes down from its most fertile soil the most precious capital it has to grow its food," Steiner said.
Accelerated warming of the Earth's atmosphere with man-made greenhouse gas emissions could exacerbate these and other challenges in the coming decades, the IPCC and Stockholm Environment Institute reports conclude. Sub-Saharan Africa is among the world's most vulnerable regions because of its low adaptive capacity.
Kenya gets about 647 cubic meters of renewable fresh water per capita, but the number will to fall to less than half of that by 2025 if supply does not keep up with population growth, according to the Vision 2030 plan. So to hedge against tomorrow's water risks, Kenya's government plans to invest tens of billions of dollars to expand hydropower alternatives, rehabilitate forest rain towers, dig rural catchments and reduce pollution.
"The reality is we have to keep working on the science to better understand what's going to happen over the long term with the climate," said Peter McCornick, director of water policy at Duke University's Nicholas Institute for Environmental Policy Solutions. "In the short term, we need to be taking actions to improve the resilience of the water systems."
The region's water systems are linked inextricably with its volatile politics.
Violence following Kenya's disputed December 2007 elections left more than 1,000 people dead and 660,000 others displaced. Former U.N. Secretary-General Kofi Annan helped broker a power-sharing agreement between Prime Minister Raila Odinga and President Mwai Kibaki, but each political camp continues to battle charges of corruption.
Many of the internally displaced have moved to slums, alongside refugees from Sudan and Somalia. Kenya has an estimated 4 million urban poor today, most of whom live on less than $1 a day, according to a U.N. estimate.
"There's this belief that if you come to Nairobi, there will be better opportunities for jobs ... but, of course, you find cities are not well-equipped to cope with such huge numbers," said Edward Kairu, chairman of the Nairobi-based African Civil Society Network on Water and Sanitation.
The Lake Victoria Basin, which includes Kenya's western and southern neighbors Uganda and Tanzania, is also experiencing rapid and unplanned growth. The basin is the home of 30 million people, about half of them impoverished.
The lake is both the region's main water source and its main waste depository. Nutrient-rich runoff feeds algal blooms that turn large swaths of the 68,000-square-kilometer lake into dead zones devoid of aquatic life.
For the past six years, Kenya, Tanzania and Uganda have been working collaboratively to achieve U.N. Millennium Development Goals by reducing lake pollution and improving sanitation. The Lake Victoria Region Water and Sanitation Initiative has improved water supplies for 143,000 people and sanitation for 40,000 others throughout the basin by rehabilitating water intake systems, expanding distribution pipelines and building kiosks with taps, U.N. officials claim.
Nongovernmental organizations have also dug latrines and hand-pumped wells throughout the crowded basin, but many of these projects fail within a few years for lack of parts and maintenance. The Global Water Challenge is working in western Kenya schools to create a sustainable water, sanitation and hygiene model that could be scaled up throughout the country, but graft by local leaders and other middlemen is constant challenge, said Tanvi Nagpal, the coalition's water and sanitation initiatives director.
"Our projects will not be sustainable unless the government picks them up," Nagpal warned. "The government must also be accountable."
The Kenyan government has made political accountability and environmental protection pillars of its Vision 2030 plan. One of its most aggressive targets is to nearly cut in half by 2012 the number of people living below the poverty line.
"Protection of the environment is the cornerstone of sustainable development and combating poverty in Kenya," Deputy Prime Minister Musalia Mudavadi vowed at the U.N. World Water Day conference in Nairobi earlier this spring.
UNEP Director Steiner commended the rhetoric but wants to see results.
"The problem has been recognized," he added. "The solution is not a matter of a lack of knowledge; the solution lies in the ability of the political system to resolve conflicting interests that exist here."
In Kenya -- one of sub-Saharan Africa's largest economies -- just 32 of 174 local sanitation authorities have sewage treatment and disposal facilities. Across the region, more than half of the population lacks access to clean water and two-thirds lacks access to basic sanitation, according to U.N. data.
Bai-Mass Taal, executive secretary of the African Ministers' Council on Water (AMCOW), predicts that most of the continent's countries will not meet the 2015 Millennium Development Goal of reducing by half the number of people without access to drinking water and basic sanitation. A key reason is that water and sanitation ministries are often outcompeted for money.
"When the water and sanitation minister presents a budget to the finance minister, he's competing with agriculture, with defense, with education, with health," explained Taal, who served as Ghana's water minister before joining AMCOW. "The agriculture minister can say, 'Give me money, and I'll double crop yields.'"
Perception is another challenge in a region where sanitation is widely regarded as a personal issue.
"'Defecation,' 'sanitation' should not be dirty words," said World Bank managing director Ngozi Okonjo-Iweala, formerly Nigeria's minister of finance. "They need not be, if there were more money and commitment to improving people's access to clean toilets and clean water."
Perhaps the biggest challenge of all is profitability.
Public- and private-sector utilities are often reluctant to make capital investments in areas where illegal water connections are common. The people who steal water are often the poorest and least politically powerful.
"Water for drinking and sanitation is important, but as a government, you need to make money," Sierra Leone's energy and water minister, Ogunlade Davidson, said on the sidelines of a recent meeting of water ministers and donors in Washington, D.C. "If you don't make money, then it is difficult to sell, because you have other demands from society."
The World Bank is expanding a pilot output-based aid program in Kenya as a way to reduce corruption and encourage capital investment in new infrastructure. Water and sanitation providers would receive bank funding after they deliver services, according to bank program managers.
Entrepreneurs are also seeking to surmount the financial challenge in the slums of Nairobi.
Toilets, water taps as status symbols
Mathare's Ikotoilet -- one of 15 in Nairobi -- is the brainchild of David Kuria, an architect and CEO of the startup venture Ecotact Ltd. The facilities are designed to be socially, economically and environmentally sustainable by combining community ownership, affordable sanitation and entrepreneurship.
Kuria's for-profit company owns the Mathare Ikotoilet, but local residents manage it. The facility includes waterless urinals and drinking water that is treated with ultraviolet light.
Each of Kuria's Ikotoilets, which number more than three dozen across Kenya, costs about $20,000 to build and $3,000 to maintain per year. To supplement the user fees and boost foot traffic, some of the facilities house snack vendors and other small businesses.
Kuria has hopes of plastering banking and telecom advertisements on the sides of Ikotoilets and turning human waste into fertilizer and bioenergy.
"In order to be commercially sustainable, these must be profitable," said Kuria, who has attracted seed money from the Acumen Fund and other high-profile donors. "We need a component of cash generation to ensure that they're able to recruit and hire boys and girls to manage these facilities."
In order to persuade slum residents to pay for toilets, showers and taps, Kuria is trying to make sanitation a status symbol. Kuria modeled Mathare's Ikotoilet after a prototype he built in Uhuru Park, a lush downtown mall popular with the office lunch crowd.
Each facility is painted brown and white and features a stylish sign.
"We're telling people: 'Imagine yourselves using this modern facility; imagine you can drink water from the tap,'" he added.
Kuria has hopes of securing World Bank funding and plans to build Ikotoilets in Tanzania and Uganda next. Ultimately, he wants to transfer ownership of the facilities to local citizens' boards or governments.
African Civil Society Network on Water and Sanitation Chairman Kairu, who also runs the Nairobi nonprofit Maji na Ufanisi, is implementing a similar model in the city's slums.
Like the Ikotoilet, Maji's sanitation blocks include showers, toilets and taps. Community boards run the facilities and set user fees.
Unlike the Ikotoilet, Maji's sanitation blocks lack entrepreneurial frills and septic tanks. Community groups must procure land and put money toward construction of the facility; utility pipes provide the water.
Nairobi Water Co., a wholly owned subsidiary of the Nairobi City Council, invested money in Maji to build five sanitation blocks that serve about 10,000 people per day in the slum of Kiambiu. Without the blocks, Kiambiu's residents would be forced to relieve themselves in pit latrines that fill up quickly or plastic bags that are flung into the bush -- a practice known as the "flying toilet."
"If those blocks were not there, those 10,000 people would most likely be stealing water," Kairu explained. "So the company finds it is in its interest, from a profit-margin perspective, to come and put money here."
Water may be life, but sanitation means "dignity" for the poor, Kairu said, echoing the words of former South African President Nelson Mandela. And if Kenya's most recent drought had an upside, he added, it was that it forced Nairobi's elite to think deeper about their changing water and world.
"They got educated about the link between water in the forest and water in their homes," Kairu said. "They used to think deforestation and drying out the forest wouldn't affect them."
Click here to view "When Rivers Run Dry," a photo gallery of images from Africa.