A septic system with a pump is a gravity system with one extra stop: effluent leaves the septic tank, collects in a pump chamber, and an effluent pump pushes it out to the leaching bed or treatment unit in measured doses. Floats in the chamber tell the pump when to run, and a higher float sets off an alarm if the level keeps climbing.
Your lot has one because gravity could not get the effluent where it needed to go. You get a bed placed where the soil works rather than where the slope happens to run. In exchange, the system now depends on electricity, on a pump that wears out, and on you answering an alarm.
Effluent pumps typically last 7 to 10 years, and replacing one typically runs $600 to $1,500. If the alarm is sounding right now, read what to do when your septic alarm is going off first. This post is the owner’s manual most people never got at closing.
Why Some Lots Need a Pump
Most conventional Class 4 systems in the City of Kawartha Lakes run on gravity: house to tank, tank to distribution box, box to bed, all downhill. A pump gets added when one of these is true.
The bed sits higher than the tank
This is the usual story on waterfront lots. The house sits low near the shore, the tank sits beside the house, and the only soil deep enough to take effluent, and far enough from the lake and the well, is up the slope. Effluent does not flow uphill, so it gets lifted.
The bed is raised above grade
Where the native soil is thin over bedrock or the water table is high, the bed is built up on imported fill. A raised or mound septic system usually needs a pump to get effluent up into that fill. Dosing helps these beds too, because sand works best with a rest between loads.
The bed is long enough that the Code requires dosing
The 2024 Ontario Building Code (O. Reg. 163/24, in force 1 January 2025) sets a hard trigger in Article 8.6.1.3. Where the total length of distribution pipe or leaching chamber required is 150 m or more, the system must have at least one pump, or a siphon in a dosing tank. Each dose must be at least 75% of the internal volume of the distribution pipe, delivered within 15 minutes, so the whole bed gets used and not just the first few metres. A big house on slow soil reaches that length quickly. The province’s Building Code page is the official entry point for Part 8.
The system has a treatment unit
The tertiary systems in our guide to advanced treatment units usually pump treated effluent to their dispersal area. Some also pressurize the distribution pipe so each dose spreads across the whole bed.
What Is in the Pump Chamber
The pump chamber goes by several names: dosing tank, pump tank, and on some properties lift station. It can be its own buried tank or a separate compartment inside the main tank, and the Code allows either. From the yard it usually shows up as a second lid or riser near the septic tank lid.
| Part | What it does | What usually goes wrong |
|---|---|---|
| Pump chamber | Holds settled effluent between doses | Rain or groundwater getting in through a loose lid or riser |
| Effluent pump | Submersible pump that pushes the liquid out | Worn bearings, burned-out motor, jammed impeller |
| Floats | Tell the panel when to start, stop and alarm | Tangled on the pump or pipe, stuck in debris, set at the wrong height |
| Discharge pipe | Carries each dose to the bed or unit | Freezing, a sticking check valve |
| Control panel and alarm | Runs the pump from the float signals | Moisture in the box, a blown fuse, a failed relay |
| Filter or screen | Keeps solids away from the pump | Clogs, then starves the pump |
The pump is built for liquid that has already settled in the tank, not for raw sewage. That is why a pumped system cares so much about the tank being pumped on schedule and the outlet filter staying clean. Our guide to cleaning the effluent filter covers that job.
The floats
A standard demand-dosed chamber has three floats at different heights:
- The off float, lowest, stops the pump once the chamber has drawn down.
- The on float starts the pump when effluent rises to its level.
- The alarm float, highest, trips the buzzer and light if the level keeps rising after the pump should have started.
The gap between the on and off floats sets the size of each dose, so the heights are part of the design. If the order gets swapped or a float slips on its cord, the pump short-cycles, never runs, or runs with no working alarm above it. Some chambers use a single float for on and off, with a separate alarm float above.
Demand dosing and timed dosing
Demand dosing is the simple version. The pump runs whenever the chamber fills to the on float, so your water use reaches the bed more or less as it happens. A Saturday of laundry and showers becomes a string of doses close together.
Timed dosing puts a repeat-cycle timer in the control panel. The pump runs for a set time, rests for a set time, and repeats, so the morning and evening peaks get stored and spread across the day. The floats turn into signals: one lets the timer run once there is enough liquid, an override float lets the pump run off-schedule if the level keeps climbing, and the alarm float sits above both. You see timed dosing mostly in front of treatment units and sand-based beds, where a heavy slug of effluent is exactly what the design is trying to avoid.
The practical difference for you: on a timed system, a day of unusually heavy water use can bring the alarm on even with a healthy pump, because the timer is deliberately holding back how much goes out. Still worth a call. Not always worth panic.
Check valve or weep hole
After each dose, the water left in the discharge pipe either stays in the pipe or drains back into the chamber. A check valve holds it in the pipe. In cold climates many designs skip the check valve and use a small weep hole instead, so the pipe empties after every dose and cannot freeze. A University of Minnesota onsite researcher explains the trade-off in this piece on pump supply lines: drain-back protects the pipe from freezing, and a check valve stops that water flowing back through the pump.
Which one you have depends on how deep the pipe runs and how the dose was sized. Don’t add or remove a check valve yourself. It changes the dose and the pipe’s winter behaviour.
The control panel and alarm
Where the Code requires a pump or siphon, it also requires a device that gives both an audible and a visual high-water alarm. Usually that is a small box on an outside wall, in the garage or on a basement post, with a light, a buzzer and a silence button. Some panels also have a test switch or a hand-off-auto switch. The label inside the panel door tells you what yours has.
Living With a Pumped System
A pumped system asks for a few habits a gravity system never needed.
Do
- Find the panel and the pump breaker now, not at 2 a.m. Check whether the pump and the alarm share a circuit. If they do, one tripped breaker kills the pump and the warning together.
- Test the alarm once or twice a year if your panel has a test switch. A buzzer that died quietly is worse than none.
- Ask for the pump chamber to be looked at during every pump-out: floats, pump, and any sludge that has carried over from the tank. Most households pump every 3 to 5 years, and a standard pump-out on a 1,000 to 1,500 gallon tank runs $300 to $600.
- Keep wipes, grease and anything else that belongs in the garbage out of the drains. They hit the filter first and the impeller second.
- Plan for long outages. Our guide to septic systems in a power outage covers how much time a pump chamber gives you and why a generator needs a transfer switch put in by an electrician.
Don’t
- Don’t switch off the pump breaker to stop the noise. The silence button stops the buzzer; the breaker stops the only thing moving water out. Our guide on how to turn off a septic alarm safely walks through the difference.
- Don’t open the chamber to have a look. Pump chambers can hold sewer gases that are dangerous to breathe. Never enter one, lean into one, or put your head over an open lid, and leave floats, wiring and the pump to someone equipped for it.
- Don’t keep resetting a breaker. Once is reasonable. If it trips again, leave it off and call.
- Don’t drain a hot tub or pool into the house plumbing. A chamber sized for household flow can’t absorb it.
When the Alarm Goes Off
A high-water alarm means the chamber is filling faster than the pump is emptying it. The chamber holds a fixed and fairly small volume, so the margin is shorter than on a gravity tank. The usual causes, roughly from most to least common, are a stuck float, a tripped breaker or lost power, a failed pump, water getting in after heavy rain, and a fault in the control panel.
Silence the buzzer, cut water use hard, and call. Our write-up on septic lift station alarms goes through each failure in order. Sewage backing up into the house, a screaming alarm, or septic smell inside gets same-day or next-morning response.
Pump Lifespan and Replacement
An effluent pump typically lasts 7 to 10 years. Grit, iron in the water, heavy use and a chamber that has run dry all shorten that.
Replacing the pump typically runs $600 to $1,500, depending on pump size and how hard the chamber is to reach. Float and panel repairs are priced after diagnosis, since they range from freeing a tangled cord to replacing parts. The effluent pump replacement cost guide covers the warning signs and what moves the price.
We diagnose before we replace. If the fix is a float, a fuse or a riser seal letting rain in, that is the quote. Pump, float and alarm work runs through our septic tank repair service.
Frequently Asked Questions
How do I know if my septic system has a pump?
Look for a second lid or riser near the septic tank lid and an alarm box on an outside wall, in the garage or in the basement. A raised bed, a bed uphill of the tank, or a treatment unit usually means a pump. Your permit drawings will confirm it, and the City of Kawartha Lakes Building and Septic Division at 705-324-9411 can tell you what records exist for your property.
What does a septic float switch do?
A float switch rides on the effluent level in the pump chamber and signals the control panel when the level reaches a set height. Typically one float starts the pump, one stops it, and a higher float triggers the high-water alarm. The distance between the start and stop floats sets how much effluent goes out with each dose.
Can I turn off the septic pump when I close the cottage?
It is usually safer to leave the pump and alarm powered, because rain and groundwater can still get into the chamber while you are away, and a pump with no power cannot move that water out. Ask whoever services your system what your particular design needs before you close up for the season.
Does a pumped septic system cost more to maintain?
Yes, over time, because it has more parts that can fail. Pumping frequency is the same as any system with the same tank and household. The extra is a pump that typically lasts 7 to 10 years and typically costs $600 to $1,500 to replace, plus the occasional float or panel repair.
Have Your Pump Chamber Checked
If you have never seen inside your pump chamber, or you don’t know how old the pump is, the next pump-out is a good time to find out. We check the floats, the pump and the alarm while the truck is there.
Call (705) 702-5526 or book a visit. Most routine pump-outs are scheduled within 48 hours, and form requests get a call back within 24 hours in business hours. There is no travel surcharge anywhere in the City of Kawartha Lakes; for Peterborough County, Durham, Belleville and Haliburton, the price is quoted up front.