User blog comment:Joey.eyeball/The Sims Wiki News - 2nd November 2014/@comment-4568327-20141102004820/@comment-1519608-20141102160711

They are not in the base game. Base game = available out-of-the-box at time of purchase. If you bought The Sims 4 before now, pools were not available to you. Ergo, pools are not in the base game.