Permutit is also known as zeolite. When a sample of hardwater is percolated through a bed of powdered permutit the following base exchange reaxtion takes place making the sample of water soft.
 2Na-permutit + Ca\(^{+2}\) → Ca (permutit)2 + 2Na\(^{+}\).
 The ions Ca\(^{+2}\) causing hardness to water are absorbed by permutit releasing releasing Na\(^{+}\) and hardness is removed. When all the Na site in permutit is replaced by Ca\(^{+2}\)