A leaky water pipe can ...

A leaky water pipe can trigger landslides in hilly terrains which can cause tremendous damage both for peoples health and for property. In other areas with soils as a loes it can lead to differential foundation settlement and building collapse/costly repairs. Areas with underlying expansive clays will experience ground swelling, again leading to property damage. All of this can also be caused by leaky sewer, but because it generally operates under atmospheric pressure, potential for causing damage and size of affected areas are significantly smaller compared to pressurized water distribution pipes. So, viewing from this angle leak from the water distribution system is more severe.