Sewer Backup: A Broker's Guide

Key Takeaways

• Sewer backup is a major exposure for your clients and their policies

• Most homeowners live just 10-15 feet from potential sewage backup with no protection if they lack a functioning backwater valve

• Annual maintenance prevents most incidents, but less than 1% of homeowners do it

• Unlike weather events, sewer backups are largely controllable risks

The Critical Numbers Your Clients Need to Know Numbers Your Clients Need to Know

Your client's home sits just 10-15 feet from the municipal sewer line. When that system fails, there's typically nothing between the backup and their basement except a small valve that most people don't know exists. According to the Insurance Bureau of Canada, the average insurance payout for a flooded basement as a result of a sewer backup flood is $43,000.

How Sewer Backups Occurs?

Municipal sewer systems operate under two basic designs, each creating different risk profiles:

Combined Systems (Older Neighbourhoods)

These systems handle both storm water and sewage in a single pipe. During heavy rainfall, the pipe becomes overloaded—storm water and sewage compete for the same space, often forcing contaminated water back up through basement drains. Most systems built before 1940 use this design.

Separated Systems (Newer Neighbourhoods)

Modern systems use separate pipes for storm water and sewage. While theoretically safer, they still connect to older infrastructure and can be overwhelmed during extreme weather events.

Why Systems Fail Despite Design?

Three factors create backup conditions regardless of system age:

• Population Growth - Current usage exceeds original design capacity

• Climate Change - Storm intensities now regularly exceed historical planning parameters

• Infrastructure Bottlenecks - New systems must still connect through century-old infrastructure

Risk Factors Your Clients Face

Geographic Risk Distribution Sewer backup can occur anywhere in the system, not just low-lying areas. Even homes on hills connect to the same municipal infrastructure that can fail during system overload.

The 15-Foot Vulnerability Most residential properties sit approximately 15 feet from the municipal sewer line. This proximity means that when municipal systems back up, contaminated water reaches homes quickly and with significant volume.

Prevention Opportunities

Backwater Valve Maintenance A properly maintained backwater valve blocks reverse flow from municipal systems. However, these devices require annual cleaning to remain functional. Debris and sediment accumulate over time, preventing proper closure when needed most.

Education Gaps Most homeowners are unaware of their proximity to sewer infrastructure or the preventable nature of most backup events. This creates opportunities for brokers to add significant value through risk assessment and protection guidance.

Bottom Line for Brokers

Sewer backup represents 40% of flood claims in Canada, yet most incidents are preventable through proper home protection measures. Unlike weather-related flooding, these events typically result from inadequate maintenance of controllable protection systems.

Sources and References

1. Backwater Solutions Canada - Sewer backup statistics, 15-foot proximity data, and backwater valve maintenance requirements

2. Insurance Bureau of Canada - Canadian flood payout statistics and claim distribution data

3. Municipal Infrastructure Studies - Combined vs. separated sewer system design and capacity data

4. Climate Change Infrastructure Impact Reports - Storm intensity increases and infrastructure stress factors