Common Causes of Water Quality Failures in Ontario SDWS

Written By: Canadian Water Compliance | On

O. Reg. 319/08, small drinking water systems, sdws-water-quality-failure-ontario Tags: SDWS Ontario, water testing failure, boil water advisory causes, rural water system compliance

Common Causes of Water Quality Failures in Ontario’s Small Drinking Water Systems (SDWS)

Small Drinking Water Systems (SDWS) are critical for public health across Ontario—especially in rural areas, seasonal businesses, parks, and private facilities not connected to municipal supplies. But maintaining safe water in these systems isn’t always straightforward. Every year, dozens of SDWSs receive boil water advisories or inspection notices due to preventable issues with their water systems.

Understanding the most common causes of water quality failures is the first step to preventing them. Here’s what Ontario SDWS operators need to watch out for—and how to stay compliant with O. Reg. 319/08 under the Safe Drinking Water Act.


1. Missed or Irregular Water Testing

E. coli and Total Coliforms are required to be tested at least every two weeks during the operating season for most SDWS setups. Many failures occur because:

  • Operators skip tests due to staffing or oversight

  • Testing isn’t aligned with the operating schedule

  • Samples aren’t collected or transported correctly to an accredited lab

Solution: Set automated reminders and maintain a water testing schedule, especially for seasonal sites. Work with a certified water testing provider to ensure all documentation is valid.


2. Inadequate Disinfection or Flushing

A large number of SDWS-related water advisories stem from poor system maintenance before or during the season:

  • Systems aren’t flushed thoroughly after winterization

  • Disinfection is skipped or not performed correctly

  • Treatment equipment (e.g., UV lights, chlorinators) is out of service or malfunctioning

Solution: Ensure your seasonal start-up includes full flushing, disinfection, and testing. Keep logs for inspections. Confirm all treatment systems are functioning and maintained.


3. Equipment Failures and Outdated Infrastructure

Old pumps, deteriorating pipes, and aging pressure tanks can compromise water quality or contribute to low-pressure incidents that increase contamination risk.

Solution: Inspect and upgrade aging equipment. Include preventive maintenance in your annual planning and document all repairs or replacements for review.


4. Well Contamination from Nearby Land Use

Private wells and surface sources are vulnerable to runoff from:

  • Agriculture (manure, fertilizer, pesticides)

  • Septic fields

  • Fuel storage or vehicle maintenance areas

Solution: Regularly inspect wellheads for integrity and distance from contamination risks. Consider adding nitrate or pesticide screening to your annual testing if your SDWS is near high-risk land use.


5. Poor Record-Keeping and Administrative Oversights

Even when testing is done, many SDWS fail inspections due to:

  • Incomplete testing logs

  • No posted advisories after failed results

  • Missing maintenance or operator training records

Solution: Keep organized, up-to-date records for at least 5 years. Use logbooks, digital forms, and label posting areas for compliance.


How Canadian Water Compliance Helps Prevent Failures

We support SDWS operators across Ontario with:

  • Routine microbiological and chemical water testing

  • Seasonal start-up protocols and equipment checks

  • Log templates and compliance documentation

  • Emergency testing and Public Health Unit coordination

Whether you operate a campground, church, rural business, or seasonal venue, we help ensure your system stays safe, inspected, and open for use.

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