There’s no direct answer to this question, as the right depth of pool for water volleyball is simply dependent on the height of the players. If your kids play this sport seriously, you should get them to the sports pool, which is mostly around 3.5-4 feet deep.
Some may argue that the pool is not too deep. But ideally, that should be the case. The depth should be moderate, and your kids must be able to jump up and down the water comfortably. When the water level is too deep, jumping and swimming while the game is on might get difficult for little ones.