The homeowner's guide to septic systems in Ontario
How your system works, how to make it last, and the warning signs that it's time to call someone. Tap through the cross-section to see each part.
How a septic system works: tap any part
A live cross-section of a conventional system. On Frontenac bedrock the bed on the right is built up as a raised bed.
How a septic system works
- The tank: everything from the house drains into a buried tank. Solids settle to the bottom as sludge, grease floats to the top as scum, and bacteria break down part of the waste.
- The effluent: the clearer liquid in the middle flows out through an effluent filter to the distribution box.
- The leaching bed: perforated pipes spread the effluent through stone and soil, which filter and treat it before it reaches groundwater.
The soil does the final treatment, which is why thin soil over limestone, common around Kingston, needs a raised bed.
Make your system last
| Do | Don't |
|---|---|
| Pump the tank every 3 to 5 years | Wait for a problem to pump |
| Spread laundry through the week | Run five loads on Saturday |
| Fix running toilets and drips | Let a toilet run for weeks |
| Keep a sketch of where the tank and bed are | Build, park or plant trees over the bed |
| Point downspouts and sump discharge away | Drain the pool or hot tub onto the bed |
| Clean the effluent filter yearly | Pour grease, wipes or solvents down the drain |
Warning signs
- Slow drains throughout the house, or gurgling pipes
- Sewage smell in the yard or near the tank
- Wet, spongy or unusually green grass over the bed
- Backups into basement drains or the lowest toilet
- A well test showing bacteria or nitrates
If you notice these, cut back water use and run the symptom checker.
Pumping schedule
| Household | Tank 3,600 L | Tank 4,500 L |
|---|---|---|
| 1 to 2 people | Every 5 years | Every 6 years |
| 3 to 4 people | Every 3 to 4 years | Every 4 to 5 years |
| 5 or more, or garbage disposal | Every 2 years | Every 3 years |
Source for Code requirements: Ontario Building Code, Part 8. Homeowner guidance: Ontario Onsite Wastewater Association.
Want a professional opinion?
Send the property's town and what you need. If you're working to a closing date or a building permit deadline, say so and we'll prioritize. Answers from the tools on this page come through with the form.
Phone: 343-342-3461
Hours: Mon to Fri, 8 am to 5 pm
Office: 945 Princess Street, Kingston, ON K7L 3N6
Septic care questions
How often should a septic tank be pumped?
Every three to five years for a typical household, more often for larger households, smaller tanks or a garbage disposal. Regular pumping protects the leaching bed, which is the expensive part.
What shouldn't go down the drain with a septic system?
Grease and cooking oil, wipes (even "flushable" ones), paper towels, feminine products, medications, paint and solvents, and large amounts of bleach or harsh cleaners. A garbage disposal adds solids and shortens the time between pump-outs.
Are septic additives worth it?
Generally not. A healthy system has the bacteria it needs. Pumping on schedule and keeping the wrong things out of the drains do far more than any product.
Can I drive over my leaching bed?
No. Vehicles compact the soil and crush pipes. Keep cars, trailers, sheds, pools and hot tubs off the bed, and plant only grass over it.
How long does a septic system last?
Concrete tanks can last 40 years or more. Leaching beds typically last 20 to 30 years. Advanced treatment units last 15 to 25 years with their service contract kept up.