With an overflow pool, instead of having the water sucked in by the skimmer, it is collected in a “water tank”. The water is then filtered and redistributed to the pool through a mixture of different return inlets ( floor & multi-flow). Since the pool is already full, the incoming water automatically spills over into the water tank, creating the overflow effect. Although the circuit is “technically” not closed, it is always the same water that flows in and out of the filtration system. So, no need to worry about issues of water consumption.