As the Cambodian capital’s least-majestic waterway, the infamous “Shit Canal” is descended from greater architectural marvels intended to re-engineer the landscape.

Touring Phnom Penh's 'Shit Canal' by Drone from CityLab by Thomas Cristofoletti / Ruom on Vimeo.

This post is part of a CityLab series on wastelands, and what we squander, discard, and fritter away.

South of Preah Sihanouk Boulevard and a few blocks east from Olympic Stadium, Phnom Penh’s most infamous waterway makes its first—and largely unwelcome—appearance.

Rising above ground from a dank sewer, the drainage canal spans a few feet across, protected on either side by a small guardrail. Rising and falling in depth with the seasonal rains, the canal is filled on a typical day with a bubbling and slow-moving black sludge making its way southwards to lakes on the edge of the city.

The canal has no official name. On paper, it’s known simply as the “Boueng Trabek sewage canal,” but it’s more commonly known as the “shit canal” in English, the “loo teuk sa-ouy” in Khmer (literally, “smelly water canal”), or the more poetic French “le canal aux mille parfums” (“the canal of a thousand fragrances”). The thousand fragrances come from thousands of septic tanks and sewers that empty into the waterway.

This odor, however, and other sewage-related hazards do not keep people from living and working alongside the canal—or in some cases even directly on top of it. While mildly repulsive to many foreigners and Cambodians, the sewage canal is not atypical of 19th-century urban planning—most others have simply disappeared underground in cities from New York to Tokyo.

Built sometime between the twilight of the French protectorate and the early years of the post-independence Sangkum Reastr Niyum “golden age” of the 1950s and 1960s, the canal is also a reminder of how Phnom Penh’s urban planners have continuously struggled to transform a marshy and mosquito-infested floodplain into a modern city of 1.5 million by reshaping the natural landscape.

While less aesthetically impressive than the city’s pagodas and colonial boulevards, its underside of canals and sewers is no less important, according to Van Molyvann, Cambodia’s most preeminent contemporary architect. “The major environmental constraints on the city of Phnom Penh are flooding and drainage,” he says. “The history of Phnom Penh’s expansion is, in a sense, a hydraulic history.”


On a late Sunday afternoon, Moeun Sothear’s family is making num banh xeo, a thin pancake fried on a wok and filled with vegetables, at their food stall along a busy segment of Street 105 adjacent to the Shit Canal. Customers come and go, some eating in at a small counter and others carrying food out. The stall is in a popular location for small restaurants near a shopping plaza and a large construction site. It would be a perfect location except for the occasional wafting smell of “combined sewage” that comes in over frying food.

“Although the water in the canal smells bad, we still have many customers because our food is delicious,” says Sothear. “Some customers pack the food [and take it] home if they cannot handle the smell, and for those who can, they eat here, so [the canal] does not affect our business,” he adds. “I have been selling here for two years, so I am fine with the smell. But at first, I thought it smelled so bad and sometimes I could not handle it.”

For these inconveniences, his family gets a competitive rate on the location: rent is just $100 while a smaller spot in another part of town could cost up to $200 or $300. Moeun Sothear’s food stall brings in around $600 a month, which means his family makes a fair amount of money.

“I have been selling here for two years, so I am fine with the smell,” says Moeun Sothear. “But at first, I thought it smelled so bad and sometimes I could not handle it.” (Ricardo Perez-Solero Llosa)

The high profit margin justifies the occasional flooding during rainy season—which can reach knee-high—or the monthly fevers that have come since the business opened alongside the canal. It’s an excellent breeding ground for mosquitos and increases the risk of contracting to parasites, salmonella, gastroenteritis and hepatitis A, according to the Australian Department of Health. “I have fever once or twice per month because of the [canal] but I have no choice. This place is good for business and there are many customers,” Sothear says.

It’s the same calculation that many of Phnom Penh’s earliest residents seem to have made.

Founded in 1431 as a one-time royal capital, Phnom Penh remained a major trading-center for centuries after it was abandoned by the royal court. Chinese, Malaysian, Japanese, Indian, and Dutch merchants built up the town, braving mosquitos and flooding for the sake of Phnom Penh’s strategic location at the meeting point of the Tonle Sap, Bassac, and Mekong rivers, one of Southeast Asia’s most important waterways, according to the Paris Urbanism Agency (APUR).

Ideal for trade, the site of Phnom Penh was less ideal for human settlement. Located on a natural floodplain, the landscape was dotted with rivers, lakes, and marsh. Still, a town sprang up of raised wooden houses built on the water’s edge or floating upon it to accommodate flooding and a royal decree that only the King could build on the land, writes Penny Edwards in Cambodge: The Cultivation of a Nation 1860-1945.

When Cambodia became a French protectorate in 1863, Phnom Penh was made the capital—although little was done to improve it. As late as the 1890s, the town was more swamp than capital city, writes Edwards:

“The city was best known for its vast tracts of mosquito-infested swamp land, the stench of stagnant water and human waste, and frequent outbreaks of cholera. In the wet season, boat travel was necessary between different sections of Phnom Penh.”

The new French rulers finding the conditions intolerable and eventually brought the principles of “rational” 19th century urban planning, perhaps inspired by Georges-Eugène Haussmann’s “renovation of Paris” 20 years earlier. Starting with Phnom Penh’s French quarter, the colonial administrator Huyn de Verneville began in 1889 the long process of raising Phnom Penh with a system of dikes, landfill, and canals to drain water and sewage away from urban areas.

Molyvann writes in Modern Khmer Cities, his seminal 2003 book on architecture (an except of which is available on the City of Water blog):

The city expanded by the construction of dikes which extended away from the colonial center of the city on the banks of the Tonle Sap River. The process of building dikes and then filling in their interiors was repeated several times, creating a series of concentric arcs on which the major boulevards of the city run today: Preah Sihanouk Boulevard, Monivong Boulevard, Mao Tse Tung Boulevard are all built on dikes.

Many of these canals were used to racially segregate the city, although rapid population growth gradually did away with the capital’s ethnic zones for Europeans, Cambodians, Chinese, and Vietnamese Christians. Following a master plan, Phnom Penh expanded zone by zone as more dikes and canals were built, draining water into two major lakes south of the city whose wetlands provided a natural filtration system, according to APUR. Over the years, many of these canals were covered over becoming an underground sewer system.

At some point in the mid-twentieth century, the Shit Canal was built.

While its definitive construction date is somewhat elusive, maps from APUR detailing the expansion of Phnom Penh suggest that the contemporary Shit Canal was probably built sometime between 1943 and 1958 when the zones it flows through were gradually urbanized. It may have been built as late as the 1960s, according to Shelby Elizabeth Doyle, an American architect who has extensively researched the urban planning history of Phnom Penh and its relationship with water, but Doyle could not confirm the exact date of construction.


Building a city of canals and drains may have made sense to the 19th century mind, but it set Phnom Penh up for the kinds of long-term problems faced by other French master-planned cities like New Orleans, says Doyle, whose blog City of Water catalogues Phnom Penh’s sewage system and waterways. Taking “ideas of the Enlightenment and urban planning and imposing those ideas upon an environmental condition where they didn’t make sense has led to a lot of current-day issues,” she says.

A manmade city can, after all, still be undone by natural forces, as became apparent in New Orleans in 2005 and Phnom Penh on a semi-regular basis.

Meong Yim’s room in a derelict building along the Shit Canal floods occasionally from outside sewage and rain water. She stays because she feels safe in the community and has finally gotten used to the smell. (Ricardo Perez-Solero Llosa)

Buildings in Cambodia that have been abandoned for even a few years are quickly consumed by plants and vines in the tropical climate. The city’s French ornamental parks provide little natural absorption for floodwater and its system of canals and sewers can quickly become overwhelmed by seasonal rains. In the 21st century, problems that began in the colonial era have grown exponentially as the city is filled in with concrete and littered with new materials like plastic bags, which can easily block drains. Massive migration form the countryside to the capital means more and more sewage is flowing through its pipes and canals than ever before.

Meong Yim, a dishwasher in her fifties, has experienced the city’s sewage failures on a more personal level than most Phnom Penh residents. At her small room in a derelict building along the Shit Canal and several blocks south from Moeun Sothear’s food stall, she points several inches up the wall to mark the heights reached by a flood of sewage and rainwater. “When it rains, my house is flooded. Last year, it rained and flooded badly twice. The water comes from both rain and the canal but it’s gone after two or three hours,” she says. She stays because she feels safe in the community and has finally gotten used to the smell.

Although large luxury condominiums are rising across the canal, Yim’s small building and its surrounding lanes are signs of a pervasive urban poverty in Phnom Penh. Her room is sparse with very little furniture or indoor plumbing, which is available in a communal toilet around the corner. Making do with limited plumbing and environmental hazards are the only options for thousands of residents like Yim who live in a city with limited basic services.

Millions of dollars, meanwhile, have been spent maintaining the Shit Canal and its network of pipes and pumping stations. In 2002, the Asian Development Bank spent $4.7 million rehabilitating it and its sister Toul Sen Canal as part of a massive project to overhaul Phnom Penh’s sewage system, which fell into disrepair under the Khmer Rouge, the radical Maoist regime that ruled Cambodia from 1975 to 1979. The capital remained badly damaged under the Vietnamese occupation and into the 1990s, when Phnom Penh began to emerge from decades of war.

Since then, the Japan International Cooperation Agency (JICA) has spent $75 million on Phnom Penh’s sewage system with another $30 million in upcoming aid already planned, according to JICA’s Atsushi Uchida. Much of the funding spent on the Shit Canal has gone to systems to prevent flooding and maintain the flow of the canals to Phnom Penh’s lakes, whose aquatic plants and morning glory farms have made an effective natural filter for the city’s semi-treated sewage for the past century and a half. Until recently.


Where the Shit Canal once emptied into Boueng Trabek lake, it now spews out into a foaming pool next to a large construction site. Acres of sand have replaced much of the lake to make room for large housing developments. The ecosystem that once treated the city’s sewage is rapidly disappearing.

Farmers working in the morning glory farms, for example, have already observed a difference in water quality and are finding that they have more rashes from an excess quantity of sewage, says Taber Hand, founder and director of Wetlands Work!, a Phnom Penh-based environmental organization. “For years, [sewage] was treated adequately by the lakes, but the wetland system doesn’t have the capacity to treat the water as adequately as in the past,” he says.

The problem is compounded by the fact that more and more sewage is spewing out of Phnom Penh thanks to largely unchecked urban development.

Covering over the Shit Canal could be a fortuitous outcome for the area but one that would also lead to rapid gentrification. (Ricardo Perez-Solero Llosa)

The city may one day need to build a modern sewage filtration plant which will require overhauling its pipes, sewers, and likely the Shit Canal from a “combined sewage system” into a separated one. If the city continues to expand into the southern lakes, this will become more and more of a certainty.

Under a separate sewage system, a new version of the Shit Canal would likely carry either sewage or surface water, rather than carrying them in the same pipe. If residents were lucky it could be turned into a stormwater drain only, eliminating both the smell and bacteria risk of the canal’s current incarnation.

Covering over the Shit Canal could be another fortuitous outcome for the area but one that would also come at a price: in rapidly-developing Phnom Penh property values would quickly rise next to Street 105 and housing like Meong Yim’s would almost certainly be demolished to make way for more high-end apartment buildings or offices. The same could happen to the shopping plaza where Moeun Sothear has made a successful living despite the health hazards of the Shit Canal.

For now, though, the canal will continue its slow trudge from central Phnom Penh to the city’s southern fringes, all the while slowly bubbling with its distinctive rancid odor. If destroyed or covered, it would not be missed but the capital would certainly lose one of its most eccentric landmarks and reminder of its subterranean hydraulic history.

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