Groundwater Sewer Infiltration

Groundwater infiltration to sewers can result in

  • Significant increases in treatment costs
  • Increased risk of sewage tankering with associated costs and risks
  • Discharge of untreated sewage to watercourses


Understanding the risk of infiltration is essential to minimise these potential problems. The key to understanding infiltration is an understanding of the factors that have an impact on and change groundwater levels .


Our Approach to understanding and mitigating risks

  • Develop a detailed understanding of the groundwater regime and seasonal and abnormal variations in levels
  • Develop an detailed understanding of asset location and condition
  • Compute Groundwater Infiltration quantities for sewers under different scenarios
  • Delineate areas of high infiltration


With over 30 Hydrogeologists working from our UK offices we have developed a unique understanding of UK aquifers. This knowledge base and experience of developing some of the most sophisticated groundwater models has supported our consultants in the development of the UK’s first Groundwater Flood Risk Map.


Benefits of our approach to groundwater infiltration

  • Provides Water Companies with an appropriate understanding of groundwater regimes in relation to their sewer networks
  • Provide assistance to Water Companies in completing Infiltration Reduction Plans, using best available groundwater data and catchment understanding
  • Our approach allows us to provide you with advice/assistance on:
    • Development of Early Warning Systems
    • Return Periods for risk of sewer flooding
    • Focusing physical investigation in the identified high risk areas
    • Development of a Cost-Benefit approach to the optioneering and development of mitigation schemes
    • Optimise use of UKWIR model in InfoWorks using best available spatial groundwater level and permeability data.


Safeguard zones

Leaking sewers can pose a significant risk to Groundwater quality especially in Safeguard Zones. Our extensive track record in risk assessments of controlled waters and catchment management projects can help Water companies to:

  • Understand the impact of Sewer leakage to groundwater quality in the context of other sources in both urban and rural environments
  • Assess risk from treated effluent discharge to groundwater
  • Mitigate the need for water company upgrades through the development of catchment management approaches to reduction in phosphate loading to rivers

Please contact us for more information on our Groundwater Sewer Infiltration service.