The concrete of wastewater structures and especially sewers suffer badly due to chemical and biogenic sulphuric acid attack. Only in recent decades has it become clear that a protective lining of these structures is desirable to prevent water leaks. Yet there are also other causal factors that can lead to water infiltration into the soil in below grade wastewater structures, such as soil subsidence or erosion, degradation by plant roots or exceeding permissible loads.