Yes, if the water is genuinely big enough
Red-eared sliders are among the few reptiles on this list where group living is a real option — wild sliders pile onto the same basking log in numbers. The catch is scale. A basking log on a pond is not the same as a dock in a glass box, and sliders kept together need a very large aquarium or an indoor pond: deep water well beyond what a single turtle requires, strong filtration, and room for a chased turtle to actually get away and stay away. Two adult females are the steadiest grouping. Whatever the mix, the enclosure has to be planned around the adults these turtles will become, not the coin-sized youngsters they arrive as.
Where slider sharing breaks down
Competition centres on the dock. Basking is not optional leisure for a slider — it needs the heat and dry time to digest, regulate its body, and keep its shell healthy — so a dominant turtle that monopolises the dock is quietly damaging the health of the one waiting in the water. Males add two problems: they flutter their long front claws in the face of females and other males as courtship and challenge, and persistent males harass females until the female is stressed and injured around the neck and legs. Biting at feet and tails happens in cramped tanks of any mix, and a noticeably smaller turtle in a group is at risk of being treated as an obstacle at best.
Building a shared tank that gives everyone a turn
A workable group setup provides at least two separate basking areas, each fully heated and lit, so no turtle has to win a contest to dry off. Feed in a way that lets you confirm every turtle ate — some keepers feed the shyer turtle in a separate container of tank water — and keep the water scrupulously filtered, because several large aquatic turtles produce waste at a rate that overwhelms equipment sized for one. Visual barriers underwater, plants and structures that let a turtle break a pursuer's line of sight, and generous length for swimming all lower the daily temperature of the group. Even built well, the setup needs a backup plan: a second tank or stock tank on standby is part of honest group keeping.
Signs a group needs splitting
Separate the turtles if you see one always waiting in the water while others bask, bites or raw patches on feet, legs, or neck, a male whose chasing never lets a female rest, or a turtle that has stopped coming up to feed. Injuries on aquatic turtles belong in front of a reptile veterinarian, since wounds kept in water heal slowly and infect readily, and a turtle being harassed needs its own water while it recovers, not a return to the group that hurt it. Eggs are another group surprise: females may lay them even without a male present, and need a place to do so out of the water.
A big shared tank runs on a rota, not memory
A multi-slider setup generates real work — water testing, filter maintenance, basking checks, per-turtle feeding confirmation, dock inspections — spread across every week of the year. KinsLe Care Teams lets the household divide that work into assigned duties, from the morning basking check to the weekly filter clean, with each finished job timestamped, so the shy turtle's missed meals and the second dock's failed lamp are caught by the rota instead of discovered weeks later.