As a huge culvert discharged sewage into the flooded streets, Tejada, 50, and her family retreated indoors, while passers-by held their noses.

With no running water in their homes, kids sometimes bathed in the floodwater. Tejada worried whether the pollution would harm the health of her two-year-old and seven-month-old grandchildren.

"This is a foul-smelling place," she said of the neighbourhood where she has lived for eight years, and where the precarious wooden houses lack water and sewer service. "But we're poor. We have nowhere else to go."

Of all the environmental injustices that Pope Francis could address in the encyclical on ecology and climate, to be published June 18, lack of access to sufficient clean water is emblematic, Christiana Z. Peppard, assistant professor of theology, science and ethics at Fordham University, told Catholic News Service.

"Water is a central part of Catholic teaching on environment and social justice," said Peppard, an expert on water and ethics. "It's tangible, it's essential for life and it's a way of anchoring more general claims about justice and political economy and how climate change will disproportionately affect people living in poverty."

The encyclical comes amid indications that climate change — which Pope Francis has identified as a pressing issue — is exacerbating conflicts and social problems around the world, said Anthony Annett, climate change and sustainable development advisor to the Earth Institute at Columbia University and to the non-profit Religions for Peace.

In Africa's Sahel region, the Sahara Desert is encroaching on grazing land around Lake Chad, triggering conflicts between people who pasture animals and those who farm for a living. One of the most severe droughts in recorded history also may be contributing to conflict in that country, Annett said.

"It's over-simplistic to blame the Syrian civil war and the rise of (the Islamic State) on (climate change), but it is a major part," he said.

The connection between land and water has been drawn sharply in Brazil in recent months, as the southern part of the country, including Sao Paulo with its 20 million people, has been gripped by drought that drained reservoirs and led to cutbacks in water supplies.

Scientists attribute the drought to a combination of weather patterns and deforestation in the Amazon basin, which reduces the amount of moisture carried to southeastern Brazil by the wind.

With its large expanses of forest and network of broad, looping rivers, the Amazon region, which is shared by nine countries, appears to have an endless supply of water and trees. But its rivers are being harnessed for hydroelectric energy and poisoned by mercury from unregulated mining operations. Scientists estimate that about 20 per cent of the original forest has been lost to roads, farming, ranching, logging and other human activities.

"There are situations of privilege where some people benefit and situations of burden where other people are deprived of access" to water, land or the benefits of infrastructure projects, Peppard said.

The Amazon "is a place where I think that the idea (that) the goods of creation (are) intended for all is really important," she said. Those goods are "not for the benefit of a few corporations or governments, but need to be equitably shared."

For more than 50 years, Catholic social teaching has emphasized that economic prosperity "is not about how much your balance sheet holds, but how equitably people around the world have access to goods that sustain life," she explained.

Although Latin American economies have boomed over the past two decades, the region continues to have the world's most unequal distribution of wealth, according to the International Monetary Fund. Indigenous people are especially affected by development projects, although they often live in areas where government services such as education, health care and water and sewer systems are poor or nonexistent, said Mauricio Lopez, director of Caritas Ecuador and co-ordinator of the Catholic Church's new Pan-Amazonian Ecclesial Network, which aims to connect Church workers throughout the Amazon basin.

Many problems — including those related to water — are common to all the Amazonian countries, Lopez said. Pollution from mining, agriculture and wastewater, as well as sedimentation due to erosion resulting from deforestation, can reduce the fish on which many Amazonian communities depend for protein and livelihoods. When that problem is exacerbated by heavy flooding or a severe drought, many families are forced to migrate to cities, where they settle in poor neighbourhoods like the one where Tejada lives near the sewer overflow.

Studies have found that indigenous territories in the Amazon generally have the lowest deforestation rates, sometimes even lower than protected areas such as parks, but infrastructure projects threaten those communities.

Indigenous groups are protesting the huge Belo Monte hydroelectric dam on the Xingu River in Brazil, as well as dams planned for that country's Tapajos watershed and various rivers in Peru.

Environmentalists note that environmental impact studies for those dams and other infrastructure construction do not consider the combined impact of multiple projects. And local communities often remain without electricity despite having a dam nearby.

Although countries such as Peru and Colombia have laws requiring that indigenous communities be consulted about any development project that would affect their rights or territories, governments do not always respect the legislation, Lopez said.

Peppard hopes Pope Francis' encyclical will draw attention to the unequal distribution of resources and the connections between consumer demand in wealthy countries and the impact on natural resources and poor communities in developing countries.

"What it means to have a life of well-being or even basic sufficiency is more than gross domestic product," she said. "It's tangible realities like do (people) have clean water."

That resonates with Tejada, as she waits for the grimy floodwaters around her house to subside. The local parish has helped co-ordinate meetings between residents and government officials, and Tejada's son made a video about the pollution that won a local competition on June 5, World Environment Day. She hopes that will help draw attention to the problem, which she said affects at least 600 families.

"We just want clean water and sewer service," Tejada said. "We want the mayor to listen to us."