Bangkok residents stranded by neck-deep floodwaters on Sunday appealed for clean water and food, as Thai Prime Minister Anutin Charnvirakul cut short a diplomatic trip to the United Kingdom to monitor the response amid growing criticism online.

In the worst floods to hit the Thai capital in 15 years, life has ground to a standstill in parts of the city since Friday evening, prompting the town hall to declare a disaster in all 50 districts.

Days of incessant rains that overwhelmed Bangkok’s creaking drainage system appeared to have let up on Sunday morning, leaving residents cautiously hopeful that the water may have stopped rising.

But densely populated eastern Bangkok remains hard hit, with canals unable to drain the volume of water pouring out from inundated roads and homes.

Residents of at least two large housing complexes in the east of the city took to social media to appeal for help as a deluge that has virtually submerged cars cut them off from fresh food and water supplies.

In one block of flats in Bang Kapi district, residents said that with each passing hour without help they feared being exposed to mounting risks that come with floods in Southeast Asian megacities – including electrocution, disease and encounters with snakes flushed out from the drains.

“The water [around the flats] is chest high. No one has come to help us at all,” Siraprapha Sangseeluem, 24, told This Week in Asia.

“Someone in my neighbourhood was electrocuted. I’ve got 10 bottles of water and some mama (instant noodles) left but I’m not sure when the cooking gas will run out,” Siraprapha said.

“I’m mostly concerned about running out of water to drink because the floodwater doesn’t seem to recede at all.” She also criticised the perceived sluggish response to the flooding by the Bangkok Metropolitan Administration (BMA) as “too little, too late”. “We’re all just left to fend for ourselves and take care of each other right now,” she said.

City residents shared flood resilience tips online – including how to make “sandbags” without sand – by using plastic bags filled with floodwater to make barricades at the entrances to homes and businesses.

Others found time for a lighthearted response to a crisis beyond their control, posting videos of swimming, fishing or lying on floaties in swimwear on inundated roads.

Bangkok Governor Chadchart Sittipunt on Sunday said that if there was no more rain to add to the situation, authorities would accelerate the drainage-clearing work. “But the water cannot be drained quickly. As we pump the water out, water from higher-lying areas continues to flow in and replenish it. It will take several more days,” Chadchart said.

He added that many stranded communities wanted to evacuate and taking care of such large groups, including 30,000 residents in the Rom Klao housing estate, was challenging.

Earlier, Chadchart admitted that the BMA initially downplayed the risks of the rains, which had been raised by flood experts and city residents on social media in the days before the waters rose on Friday.

The BMA has invested huge resources in cleaning and widening drainage, especially in deluge-prone areas ahead of the peak flood risk period which runs until late October. But its efforts appear to have been thwarted by the sheer volume of water dumped down on Bangkok since late Wednesday.

An eerie calm descended over other parts of the Thai capital on Sunday, as drivers stayed off the traffic-clogged roads and residents in hard-hit areas waded through knee-high waters, pulling improvised rafts and basins to bring bottled water to stricken neighbours.

Some began counting the cost of floodwaters that came without warning and attempted to start waterlogged cars and motorbikes, although it was too early to begin a clean-up with waters sitting at around 12 inches (one foot) high in many neighbourhoods.

The disaster also prompted Prime Minister Anutin to end a trip to the United Nations in New York and then London early – conscious of the political stakes in a capital that largely did not vote him into office earlier this year yet retains outsize economic influence over the country.

“During this time all of the ministers in my cabinet will not travel overseas, including myself,” he told reporters after a walk around northeastern Bangkok.

“Our main goal is for the people to be able to return to work, for kids to go back to schools and for shops to reopen, for the public to be able to commute safely again.” Thailand is accustomed to the annual flooding season, but this year’s catastrophe has caught many by surprise. The rains were lighter but more persistent compared with the heavy storms that triggered the 2011 crisis, which killed 500 people across the country, including hundreds in Bangkok.

Bangkok, which sits in a soft clay basin that experts say is slowly sinking, is highly exposed to climate extremes. But the climate crisis is challenging the resilience of its people and infrastructure like never before.