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Septic and Wells

Effective January 1, 2021, the Township of Stone Mills now accepts new applications for On-Site Sewage Systems under Part 8 of the Ontario Building Code.

New applications and inquiries for sewage systems should be directed to Building staff via 613-378-2475 ex. 241 or via email to

Application Forms:

Payment Options:

  • Cash, debit or cheque in person at the Administrative office – 4504 County Road 4, Centreville ON or,
  • Online ePayment via credit card. When making a payment online, please ensure you input the correct payment amount and application number that was provided by building staff.

All development (residential, commercial and institutional) in Stone Mills has a sewage system which is designed to treat wastewater which goes down the drain (toilets, showers, dishwashers, washing machines, etc).

A sewage system includes a septic tank and a leaching bed — both hidden below the soil. It is critical to your health, the health of neighbours, the health of the ecosystem and your property investment that your sewage system is working properly. It is your responsibility to make sure your sewage system is in good working order.


  • Know where your septic tank and leaching bed are located on your property
  • Keep accurate records of sewage system maintenance, pump outs and service calls
  • Test your well water at least three times per year for indicator bacteria (spring, summer and fall)
  • Have your system inspected by a licensed installer or sewage hauler every three to five years and pumped out when required (house typically every three years — seasonal cottage every five plus years). Best time of year for pump out is summer or fall before the cold weather.
  • Clean the effluent filter (located in the tank where it flows to the bed) at least once a year
  • Direct surface water/drainage away from leaching bed
  • Conserve water use to reduce amount of wastewater needed to be treated

Do Not:

  • Enter your septic tank
  • Put fats, oils, paints, food waste, chemicals, pharmaceuticals, sanitary products, condoms or anything plastic down the drain
  • Use special additives that are claimed to enhance your tank or system
  • Use cleaning detergents that are high in phosphorus
  • Dig on your property without knowing where your sewage system is located
  • Drive or park over your sewage system
  • Pave over your leaching bed
  • Put an above ground pool over your leaching bed
  • Put an outdoor skating rink over your leaching bed
  • Plant vegetation over your leaching bed (e.g. garden, flower beds, trees etc.)
  • Allow livestock over your leaching bed
  • Connect rain gutters, sump pumps or storm drains into your sewage system
  • Drain hot tubs or pools into your sewage system

Signs that your system is not working properly:

  • You detect a sewer odor
  • There is effluent pond on top of leaching bed
  • Toilets, sinks or other drains are slow to drain or backing up

What to do when you suspect a problem:

  • Contact a licensed professional and have the system inspected
  • After inspection it may be necessary to have a licensed hauler pump out tank
  • If the system has "failed" it may be necessary to replace all or part of the system
  • Contact the Building Department to obtain necessary permits — if near water there many also be a need for Conservation Authority permits

See links to additional Sewage System resources and information:

Septic Smart! Understanding Your Home's Septic System

Ontario Onsite Wastewater Association

Private Wells

Contact Us

Township of Stone Mills
4504 County Rd 4
Centreville, ON K0K 1N0
Phone: 613-378-2475

Hours of Operation
Monday: 8:30am - 6:00pm
Tuesday-Thursday: 8:30am - 4:30pm
Friday: 8:30am - 12:30pm

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