A homeowner near Fenelon Falls called us last spring in a panic. Water was pooling across his yard. The toilets wouldn’t flush. There was a sewage smell coming from the basement floor drain. He thought his septic tank had cracked or collapsed.
It hadn’t. His sump pump was connected to his septic system. And after three straight days of heavy April rain, his sump pump had been running nonstop, dumping hundreds of litres of groundwater directly into the tank. The system couldn’t keep up. It flooded the drain field and backed everything up into the house.
The repair bill was over $8,000.
If you’ve got a basement sump pump and a septic system, this is something you need to understand before it costs you.
The Short Answer
No. Your sump pump should not be connected to your septic system.
Not sometimes. Not if you have a big tank. Not if your sump pump only runs a few times a year. The answer is no across the board.
A sump pump connected to septic is one of the top reasons we see system failures in the Kawartha Lakes area. It’s also one of the easiest problems to prevent.
Why People Connect Them
It makes sense on the surface. You’ve got water collecting in your basement sump pit. You need it gone. There’s a pipe running from your house to the septic tank. So you tie the sump pump discharge into that pipe and forget about it.
Most people who have a sump pump into septic tank setup didn’t do it on purpose. A previous owner or a handyman made the connection years ago. Sometimes it was done during a basement renovation when nobody thought to ask where the water would go.
Other times, homeowners just don’t realize there’s a problem. The sump pump runs so rarely in dry weather that the extra water doesn’t seem like a big deal.
But it is. And here’s why.
What Happens When You Do
Your septic system is designed to handle a specific volume of wastewater. For most homes in Lindsay, Bobcaygeon, and the surrounding area, that’s the water from your toilets, sinks, showers, and laundry. The tank is sized for that load. The drain field is sized for that load. Everything about your system is built around a predictable daily flow.
When you add a sump pump discharge to your septic system, you’re throwing that balance out the window.
Here’s what actually happens:
The tank gets overwhelmed with water. A sump pump can move 5,000 to 7,000 litres per day during heavy rain. Your septic tank might only be designed to handle 1,000 to 1,500 litres daily. That’s a massive surge of clean water flooding into a system that can’t process it.
Solids get stirred up. Your tank works by letting solids settle to the bottom and scum float to the top. The clear liquid in the middle flows out to the drain field. When a huge volume of water rushes in, it stirs up those layers. Solids that should stay in the tank get pushed out into the drain field.
The drain field floods. Too much water saturates the soil. The drain field can’t absorb or filter anything. Effluent rises to the surface. You get soggy spots, standing water, and sewage smell in your yard.
Sewage backs up into the house. When the system is completely overwhelmed, wastewater has nowhere to go but back up through your drains. This is exactly what happened to our customer in Fenelon Falls.
The drain field fails permanently. If solids reach the drain field and clog the soil, the damage can be irreversible. You may need a full drain field replacement, which can cost $10,000 to $30,000 or more.
This is one of the most common causes of septic system failure. And it’s entirely preventable.
Is It Legal in Ontario?
Under Ontario’s Building Code, connecting a sump pump to a septic system is not permitted. The Ontario government’s guidelines on septic systems make it clear that only sanitary sewage should enter your septic tank. Groundwater, rainwater, and surface water are all excluded.
Municipal bylaws in the City of Kawartha Lakes reinforce this. If an inspector finds a sump pump connected to septic during a property inspection or septic assessment, they can require you to disconnect it. If you’re selling your home, it could delay or derail the sale.
The rules aren’t arbitrary. They exist because a sump pump septic system connection will eventually cause failure. It’s not a question of if. It’s when.
Where Should the Sump Pump Drain Instead?
There are a few proper alternatives. The right one depends on your property, your lot grading, and local regulations.
1. Discharge to the yard surface (away from the house).
This is the most common solution. Your sump pump line runs through the foundation wall and discharges onto the ground at least 3 to 4 metres from the house. The ground should slope away from the foundation so the water doesn’t circle back.
Make sure the discharge point is also well away from your septic tank and drain field. You don’t want to saturate the drain field with surface water either.
2. Discharge to a dry well.
A dry well is a buried pit filled with gravel that lets water slowly seep into the surrounding soil. This is a good option when you don’t want water running across your lawn or your neighbour’s property.
3. Discharge to a storm sewer or ditch (where available).
In some areas around Kawartha Lakes, there are municipal storm drains or roadside ditches that can accept sump pump discharge. Check with the City of Kawartha Lakes before connecting to any municipal system.
4. Discharge to a French drain.
A perforated pipe buried in gravel can distribute the water over a larger area underground. This works well on lots where surface discharge isn’t practical.
Whatever option you choose, the key rule is the same. Keep clean water out of your septic system. Your tank and drain field should only handle household wastewater.
Not sure what setup makes sense for your property? Call us at (705) 242-0330 and we’ll help you figure it out.
How to Disconnect Safely
If you suspect your sump pump is draining to your septic system, here’s how to confirm it and fix it.
Step 1: Find where the sump pump discharge line goes.
Follow the pipe from your sump pit. If it connects to a drain line that runs to your septic tank, you’ve found the problem. Sometimes the connection is hidden behind drywall or buried under a basement floor slab, so it’s not always obvious.
Step 2: Hire a licensed contractor to reroute the line.
This isn’t a complicated job, but it needs to be done right. A contractor will cap the old connection to your septic line and run a new discharge line through the foundation wall to one of the proper discharge points listed above.
Step 3: Have your septic system inspected.
If the sump pump has been connected for a while, your system may have taken damage you can’t see. The drain field might be partially clogged. The tank may need pumping sooner than expected. We recommend a full inspection to make sure everything is still working properly.
We helped a family near Coboconk last fall with exactly this situation. They’d owned the property for six years and never knew the sump pump was tied into the septic. A routine pumping visit revealed the connection. We rerouted the discharge line to the yard and pumped the tank. Their system has been running perfectly since.
If your system is already showing signs of failure, don’t wait. The longer a sump pump feeds water into your septic, the worse the damage gets.
Want us to check your system? Book an inspection today or call (705) 242-0330.
Frequently Asked Questions
Can a sump pump drain to a septic system?
No. A sump pump should never drain to a septic system. Sump pumps move groundwater, which is clean water your septic tank isn’t designed to handle. Sending it to the tank overwhelms the system, pushes solids into the drain field, and can cause total system failure. Discharge your sump pump to the yard surface, a dry well, or a storm drain instead.
What happens if my sump pump is connected to my septic?
During dry weather, you might not notice any problems. But when it rains heavily and the sump pump runs frequently, the extra water floods your septic tank. This stirs up solids, overloads the drain field, and can cause sewage to back up into your home. Over time, it can permanently damage your drain field and lead to a costly replacement.
How do I know if my sump pump is connected to my septic?
Follow the discharge pipe from your sump pit. If it connects to the same drain line that carries wastewater to your septic tank, they’re connected. Signs include your septic system struggling during rainy periods, frequent high-water alarms, or your drain field getting soggy after storms. A septic professional can confirm the connection during an inspection.
How much does it cost to disconnect a sump pump from a septic system?
Rerouting a sump pump discharge line typically costs $500 to $1,500 depending on the complexity and how far the new line needs to run. Compare that to $10,000 or more for a drain field replacement and the math is obvious. It’s one of the cheapest things you can do to protect your septic system.
Protect Your System Before It’s Too Late
A sump pump connected to septic is a ticking clock. It might cause no visible problems for months or even years. But eventually, a heavy rain will push your system past its limit. And by then, the repair costs are massive.
If you live in Kawartha Lakes, Lindsay, Bobcaygeon, Fenelon Falls, or Coboconk, we can inspect your system, confirm whether your sump pump is connected, and disconnect it properly if needed. We can also check whether your drain field has taken any damage and recommend next steps.
Regular septic tank maintenance catches these issues early. And knowing what septic pumping costs in Ontario helps you budget for the upkeep that keeps your system running for decades.
Call us at (705) 242-0330 or book online to schedule an inspection.