Despite receiving only moderate rainfall, much of Mumbai sank on Sunday, thanks to four key factors: overflowing Mithi River, Vakola River, Vihar Lake and a high tide of 4.83 metres at 2.30 pm. Coupled with the high tide, the water from Vihar lake and Vakola River also emptied into Mithi, which not only increased its level above the danger mark but also made it rise above sea level.

Officials from the BMC's storm water drain (SWD) department said the tide started to rise around 11 am and Mithi's water level crossed the maximum safe limit, rising to 4 metres. "At one point, the water level of Mithi River was 6 inches, 1 foot higher than the sea level, since the seawater had started flowing back into Mithi. Due to this, many areas in the eastern suburbs remained waterlogged. The water will recede gradually," said a senior civic official from SWD department.