As Mumbai braces for the monsoon with massive desilting operations, clearance of chronic garbage spots and activation of flood mitigation systems, another hidden sanitation battle unfolds deep inside the narrow bylanes of the city’s old chawls.In the dark underbelly of these crumbling neighbourhoods lie thousands of “house gullies” — airless gaps between buildings so narrow that even sunlight barely enters. Choked with sludge, sewage, broken glass and rotting waste, these lanes have quietly evolved into some of Mumbai’s most hazardous sanitation pockets.Every week, a cramped lane in Dongri becomes witness to a grim relay of labour. Armed with reflective vests, hard hats and long iron rakes tied to bamboo poles, teams of conservancy workers wedge themselves into house gullies barely a foot wide. Unable to move freely, they work in a human chain, the first labourer scraping garbage from the tightest corners before passing it down the line until it is dumped into rubber baskets and ferried away in compactors.Wedged between rickety, decades-old chawls, nearly 4,900 of these existing narrow lanes were originally meant to function as duct spaces for water pipelines, electric cables and sewage lines running between parallel residential structures.Over the years, however, the gullies have evolved from utility corridors into informal dumping grounds. In the absence of adequate space inside cramped chawls, residents routinely throw household waste into the lanes through their windows. As the garbage accumulates, it mixes with sewage and drain water flowing through the pipelines, creating a sludge-filled breeding ground for mosquitoes, rats and even snakes.Recently, one such house gully in Pydhonie’s Ismail Curtey Lane became a roadblock for police investigating the mysterious deaths of four members of the Dokadia family allegedly linked to rat poison consumption. According to officials, police were unable to access the cramped gully or trace remnants of the poison bottle believed to have been discarded into the heap of waste. Relatives of the family said the building, like several others in the locality, was heavily infested with rats.The house gullies of MumbaiMumbai is home to at least 4,943 house gullies — narrow lanes wedged between old chawls that have, over the decades, transformed into some of the city’s most persistent sanitation blackspots.Story continues below this adRecords accessed by The Indian Express show that nearly 98 per cent of these gullies are concentrated in South Mumbai localities such as Dongri, Masjid, Mumbadevi, Kalbadevi and Walkeshwar. Civic data shows that the highest number of house gullies are located in C ward — encompassing Chirabazaar, Pydhonie and Bhuleshwar — which alone has 1,640 gullies. This is followed by 918 gullies in B ward (Dongri, Masjid, Bhendi Bazaar), 915 in D ward (Grant Road, Haji Ali) and 889 in E ward. A ward, covering Colaba, Fort and Churchgate, accounts for another 460 gullies.According to senior BMC officials, the prevalence of house gullies in South Mumbai is rooted in the unplanned construction of chawls during the 19th century, when buildings were erected in extremely close proximity within the island city’s dense urban fabric.“Unlike the suburbs, which developed later and were more planned, the chawls of South Mumbai are very old and were constructed in tight spaces. The narrow gaps left between these chawls eventually became house gullies. Pipelines for water, sewage and electric cables run through these lanes,” a senior BMC official told The Indian Express. Mumbai is home to at least 4,943 house gullies — narrow lanes wedged between old chawls that have, over the decades, transformed into some of the city’s most persistent sanitation blackspots. (Express Photo/Amit Chakravarty)Much like the gullies themselves, the chawls surrounding them are marked by cramped living conditions, often housing large families in tiny single-room tenements. “Their kholis are extremely small, sometimes barely 10×10 feet. Families hardly have enough space for themselves, let alone to store garbage bins. With larger families, the volume of waste generated is also higher. As a result, many residents end up throwing garbage directly into the house gullies through their windows,” the official explained.Story continues below this adAccording to the civic body, even after waste is collected from buildings every morning, fresh garbage accumulates by afternoon and is dumped into the gullies. The waste ranges from clothes, foil and plastic wrappers to bottles, broken utensils, glass and kitchen refuse.In several house gullies along Dongri’s M A Sarang Street, heaps of garbage rise almost to the level of first-floor windows. “The BMC cleans the lane regularly, but by evening the garbage returns to square one,” said Irfan Shaikh, a resident and owner of Tawakkal Eatery on M A Sarang Street. “The area is infested with mosquitoes and the foul odour has become unbearable. Sometimes the waste even spills onto the streets.”Another resident from a chawl on Dongri’s Tandel Street, requesting anonymity, said, “We try to keep the area around our house clean, but unless everyone cooperates, nothing changes. Rats are a huge nuisance, they not only run through the gullies but also enter our homes.”Amid the stench, overflowing garbage and growing pest infestation, the city’s house gullies have emerged as a major public health and sanitation challenge for both residents and civic authorities.Story continues below this adHow the BMC cleans house gulliesMumbai’s house gullies first drew serious civic attention in 1994, after the plague outbreak in Surat triggered nationwide concern over urban sanitation and waste management.While the Brihanmumbai Municipal Corporation (BMC) had long earmarked funds for improvement works in these narrow lanes, it was only in 2013 that the civic body launched a dedicated weekly drive to clean house gullies across the island city. “Most of these house gullies technically fell under private jurisdiction. But residents would frequently approach local corporators complaining about the filth and lack of cleaning,” a senior official said. “In 2013, then BMC commissioner Sitaram Kunte directed the Solid Waste Management department to put a proper mechanism in place after repeated complaints started pouring in. That is when regular cleaning and sanitisation drives began.”Today, across the five island city wards, the BMC deploys hundreds of workers to clean these lanes. Of the city’s 1,776 “chronic” house gullies — extremely narrow lanes that are difficult to access — many are cleaned through conservancy workers hired via NGOs. While wider gullies can often be handled by a single worker, the more cramped lanes require teams of three to four labourers.“It takes us almost three hours to clean one small chronic gully,” said Babu Naidu (28), who has been cleaning house gullies for the past nine years. “We start at 8 am and work till 3 pm. In some lanes, we can barely move our hands. At most, we manage to clean three gullies in a day.”Story continues below this adStanding beside a heap of broken glass and discarded mirrors pulled out from a lane, another worker said injuries on the job are common. “Our mukkadam (contractor) informs residents before we start work and asks them not to throw anything while we are inside. Still, people continue throwing objects from above and sometimes we get hurt. We have to constantly watch out for broken glass and mirrors dumped in the gullies,” he said.In South Mumbai, the BMC’s own staff clean house gullies daily, while the chronic gullies are cleaned weekly through conservancy workers hired via NGOs. “Every gully comes with its own challenge,” said an official from the Solid Waste Management department in B ward. “If the lane is relatively wider, one worker can clean four or five gullies in a few hours. But in the really cramped ones, we need at least three workers to clean a single lane together.”Officials in B ward — among the city’s worst-affected areas — estimate that nearly 50 metric tonnes of the 110 metric tonnes of waste generated daily comes from house gullies alone. “A large portion of the waste is wet because it gets mixed with sewage and drain water flowing through the lanes. Once that happens, segregation and processing become nearly impossible,” the official said.Civic records show that while house gullies range from one to four feet in width, nearly 1,158 are less than a foot wide, making cleaning operations extremely difficult. To navigate these spaces, workers use long iron rakes attached to bamboo poles, solid rubber tyre baskets, gloves and spades.Story continues below this adThe BMC had earlier attempted a pilot project to install garbage chutes in house gullies in D ward, but the experiment failed. “The waste started accumulating inside the chute itself and eventually clogged the system,” a civic official said.‘Number of gullies may be shrinking, but the crisis persists’Over the past few years, the number of house gullies in Mumbai has gradually declined due to the cluster redevelopment of old chawls. While the city currently has 4,943 house gullies, civic records show that the number stood at 5,249 until 2024.According to Amin Patel, MLA from the Mumbadevi constituency, one of the worst-affected pockets in the island city, sanitation conditions inside these remaining gullies have continued to deteriorate despite regular civic drives. “Many of these gullies are extremely inaccessible, but the BMC’s cleaning drives also need to become more consistent,” Patel told The Indian Express. “In several places, heaps of garbage rise almost up to the first floor. The situation on the ground is alarming because pipelines running through these gullies frequently get damaged, leading to contamination of water supply. Despite repeated cleaning drives, we continue to receive sanitation complaints from these areas. In many cases, residents are forced to spend money from their own pockets to hire private contractors to clean the gullies.”Patel said the BMC must earmark a dedicated fund specifically for the cleaning and maintenance of house gullies and ensure adequate allocations at the ward level.Story continues below this adAt present, the civic body spends nearly Rs 20 crore on cleaning house gullies across the five island city wards spanning A to E wards. The funds are routed through the BMC’s Solid Waste Management department, which received an allocation of Rs 5,740 crore in the 2026-27 civic budget.Waste management activist Rishi Agarwal, who has worked in the sector since 1995, said that while redevelopment and improved collection systems have helped reduce the problem to some extent, the larger sanitation crisis remains unresolved. “Sanitation cannot depend on the typology of a building,” Agarwal said. “Even in chawls, waste management systems should be robust enough to ensure that house gullies are not used as dumping grounds. Had the BMC imposed stricter penalties on buildings with dirty gullies, this problem may not have continued well into the 21st century.”