Phosphates and zeolites act as water softeners. Hard water contains calcium salts which greatly reduce the surfactant effect of soaps and detergents. Zeolite A is a aluminiosilicate. The cations are loosely bound and can easily be replaced by other cations such as calcium. This is the principle of ion exchange.
Zeolites thus remove the calcium from solution.
As far as is known they have no negative effect on the environment, unlike phosphates.