Footage shows the playful creatures enjoying the water together while residents watched in Prince Charles Crescent on April 6.
The marine mammals swam closely with each other and even hunted the small fish being cared for by residents in a nearby pond.
With temperatures reaching 31C, they enjoyed the refreshing dip in the cool water.
Resident Yvonne Chan said the animals were peaceful and did not damage anything but they almost ate all of the ornamental fish they have in the compound.
"I felt happy when the otters came," she said. "I have always been fascinated by them. They didn’t harm anyone nor damage the property so all was fine."
The resident added that the otter family might have been looking for food when they saw their backyard pond filled with fish.
She said: "I think they were hungry and looking for around the area. We have a backyard pond by the garden which might have drawn them to our block. The swimming pool might have just been an extra perk."
The sea otter is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters usually weight between 14 and 45 kg making them the heaviest members of the weasel family but among the smallest marine mammals.
Singapore has a thriving population of otters, which swam across the Johor Straits from Malaysia in the 1990s. They now live all over the island.