Tuesday, 6 December 2011

Stormwater Infiltration and Inflow

In HRM, there are two types of wastewater collection systems. Separated wastewater systems are designed to carry wastewater only. In older areas of Halifax and Dartmouth, combined systems exist that accept both wastewater and stormwater. When stormwater unnecessarily enters the wastewater system, the excess water load can cause a range of problems.

Stormwater can enter the wastewater system in two ways:
Infiltration (groundwater entering through cracks and leaks in the wastewater pipes) or Inflow (stormwater entering the system through a direct connection like sump pumps, drains or catchbasins).  Stormwater that enters the wastewater system ends up being collected and treated unnecessarily, which causes extra strain on  treatment plants and can lead to  combine sewer overflows (CSO) in heavy rains. CSOs cause untreated wastewater to overflow directly into natural water bodies leading to environmental and health risks. Infiltration and inflow can also cause sewer backups in people’s homes and can add to operating costs of treatment facilities which ultimately leads to higher rates for customer.  To address this serious issue, stormwater needs to be better managed at the source, by retaining runoff (allowing it to soak into the ground, or be collected and reused) on-site instead of allowing it to enter the wastewater system.

To reduce the frequency and magnitude of infiltration and inflow events,  Halifax Water has designed a Stormwater Inflow Reduction (SIR) Program to help customers indentify ways to better manage stormwater on their properties. The number one tip for property owners? Disconnect your downspout if it is directly connected to the wastewater system. This water can be redirected onto your lawn and collected in a rain garden or rain barrel, or allowed to directly soak into the ground.

If you have concerns about where your water is going, you can call 490-RAIN (7246) to have a free inspection of your property. Click here to find out more.


  1. Water infiltration woes affect the quality of water in the community and cause pipe leaks and damages. One measure that can help minimize the influx is to direct the flow into green spaces like lawns and gardens. Open spaces and green infrastructures can make a valuable contribution to managing water run-off.

  2. When will you be doing another article on this subject? 

    Amela Jones
    waste water services