Sewer networks are expected to operate with minimal or no interruptions. The complex nature of randomly occurring failures in sewer networks arising from blockages significantly adds to the cost of operation and maintenance. Blockages are significant due to sewage backup or basements flooding, resulting from their occurrence. Continuous performance assessment of sewer pipe networks is necessary to ensure a required level of service at an acceptable cost. This study provides insight into the performance of the sewer pipe networks by assessing the proneness of the network to blockages and drawing inferences at a holistic strategic level of influential explanatory factors of blockage proneness, using data available in the VASS statistics database managed by Swedish Water and Wastewater Association. Results indicate that medium sized municipalities are prone to at least 30% more blockages per km per year compared to other municipalities. A hypothesis of explanatory factors includes, reduced flow volumes and design flow depth resulting in flow velocities below self-cleaning velocity in sewer pipe networks encouraging the sluggishness of flow and increased possibility for sediment deposition and accumulation in sewer leading to blockages. This is also exacerbated by the deposition of non-disposables (wet wipes, baby diapers, hard paper etc.), accumulation of FOGs in sewers and increased water conservation measures. Blockages also show a trend indicating occurrence may have a constant return frequency in medium – less than small sized municipalities.