Abstract: A wetness indicator used on absorbent pads such as diapers for visually signalling the presence of water. The wetness indicator preferably comprises a hydratable salt mixture applied to a water permeable membrane and visible from an external observation of the absrobent pad. The hydratable salt has the characteristic of changing from the color it exhibits in its normal, anhydrous state to a contrasting color when it becomes hydrated. The wetness indicator is physically disposed within the pad so that it contacts water as it reaches the absorbent layers of the pad. The wetness indicator is constructed so that the hydratable salt mixture does not leach back into the absorbent layer or into contact with the wearer of the pad. The hydratable salt may be arranged to combine with a binder upon hydration to reduct toxicity.