JAMB - Chemistry (2000 - No. 16)
A side effect of soft water is that
it gives offensive taste
excess calcium is precipitated
it attacks lead contained in pipes
it encourages the growth of bacteria
Paliwanag
Water is a solvent, and soft water is more aggressive at leaching metals from pipes. Soft water has little or no minerals, so it pulls minerals from the pipes it travels through. Thus, Soft water can dissolve lead from pipes because it's more reactive and lacks minerals.