How Property Managers Should Check Building Drains Before Winter
Before the first hard freeze, a multi-unit building should get a drain walk-through that covers the main stacks, the building sewer, any backwater valves, the sump pit, parking garage drains, roof drains and the backflow preventers. Most of these take minutes to check, and the ones that turn up trouble are far cheaper to fix in October than in January, when the ground is frozen and a backup affects every unit on the line.
This is the inspection order we suggest for apartment buildings, condos and small rental blocks.
Start with the building's history
Pull the service records before anyone opens a cleanout. Note which stacks have backed up in the past two years, which units complain about slow kitchen drains, and when the main line was last cleaned or camera-inspected. A building that has had two backups on the same stack in a year is telling you where to look first.
Also check whether anyone has a camera video of the sewer lateral on file. That footage gives you a baseline: roots, offsets and sags that were visible then are usually worse now.
Kitchen stacks and horizontal branches
In apartment buildings, kitchen lines cause more service calls than anything else. Cooking grease, rinsed food and the occasional "flushable" wipe build up on the walls of the stack and the horizontal runs in the basement ceiling.
Things to look at:
- Slow drains on lower floors. When upper units drain fine and the second floor gurgles, the restriction is usually low in the stack or in the horizontal branch where it turns toward the main.
- Cleanout caps. Make sure every cleanout is accessible, not boxed in behind drywall or storage shelving, and that the caps turn.
- Staining around joints. Rust streaks or mineral trails on cast iron point to a joint starting to fail.
If the kitchen stacks have not been cleaned in two or three years, fall is a good time to schedule hydro-jetting. A cable machine punches a hole through grease; a jetter scours the pipe wall back toward its original diameter. Our drain cleaning and hydro-jetting service covers both, and the crew can run a camera afterward so you can see the result.
The building sewer and lateral
The pipe that leaves the building and runs to the city main carries everything. On older buildings it is often clay or cast iron, and tree roots find the joints every summer and fall.
Have the lateral camera-inspected if any of these apply:
- The building is more than 40 years old and the lateral has never been scoped
- There are mature trees between the building and the street
- The main cleanout has backed up in the past year
- You see sinkholes or low spots in the lawn or paving above the line
Roots can be cut and the line jetted as maintenance, but a collapsed section or a bad offset needs repair. If the camera shows damage, a trenchless option such as pipe lining or pipe bursting is often possible, which matters on a property where digging would mean tearing up a parking lot. The trade-offs are covered in our post on trenchless sewer replacement versus digging.
Backwater valves
Many buildings in Montréal, Laval, Toronto and other cities with combined sewers have backwater valves on the lowest drains, and several municipalities require them for fixtures below street level. A valve that is stuck open does nothing, and one stuck closed backs up the building's own wastewater.
For each valve:
- Open the access cover and confirm the flap or gate moves freely.
- Remove debris, grease and anything that has lodged in the seat.
- Check that the cover gasket is intact.
- Make sure the valve is not buried under storage boxes or a bike rack.
Most valves should be cleaned at least once a year, and fall is the right time, before snowmelt and spring rain load the sewer. If your building does not have one on the lowest floor, read our guide on backwater valve installation for what the work involves.
Sump pits and pumps
If the building has a sump, test it before winter, not during the first thaw.
- Pour water into the pit until the float lifts and confirm the pump starts, empties the pit and shuts off cleanly.
- Look at the discharge line outside. It should not be crushed, disconnected or pointed at a walkway where it will freeze into a sheet of ice.
- Check the check valve on the discharge. A failed check valve lets water fall back into the pit and makes the pump cycle constantly.
- If there is a battery backup, test it with the main power cut and note the battery's age.
A pump that hums but does not move water, or a float that sticks against the pit wall, should be replaced now. Sump work and backwater valves are part of our sump pump and backwater valve service.
Parking garage and area drains
Underground garages collect sand, salt and grit from every car that comes in. By mid-winter the trench drains and catch basins can be packed solid, and the water sits on the slab.
Before the snow:
- Lift a few grates and check how much sediment is in the trap or sump below.
- Confirm that oil and grit interceptors have been pumped on the schedule your municipality or your own records call for.
- Clear exterior area drains at ramp bottoms and stairwells. A blocked drain at the bottom of a ramp turns into an ice rink, and a blocked stairwell drain can flood a basement door.
Garage drain and catch basin vacuuming is covered on our stormwater and catch basin service.
Roof drains
Flat-roofed apartment buildings shed a lot of water through a small number of interior drains. Leaves and debris from fall storms settle around the strainers.
Have someone go up and clear the strainers, confirm the domes are in place and check that water is not ponding around any drain. Then check the interior leaders where they are exposed in the top-floor ceiling or the mechanical room. A roof drain that freezes because water sat in it for a week can split the pipe inside a wall.
Backflow preventers and test dates
Most multi-unit buildings have at least one backflow preventer on the domestic water service, and many also have one on the fire line and on boiler or irrigation connections. Cities set the testing rules: Toronto, for example, handles backflow prevention under its water supply bylaw (Municipal Code Chapter 851), and most US jurisdictions require an annual test by a certified tester with results filed with the water utility.
Check the tag on each device for the last test date. If the annual test is due in the next few months, book it now rather than in a cold mechanical room in February. Our post on commercial backflow testing requirements explains what the test involves.
Hose bibs and a written record
Last, shut off and drain any hose bibs that are not frost-free and have irrigation blown out. Then write the results down, drain by drain, with dates. That one-page record shows a contractor where the line was last inspected when a backup happens in January.
Frequently asked questions
How often should an apartment building's drains be hydro-jetted?
It depends on how the building is used. Many multi-unit buildings jet the kitchen stacks every one to three years, and buildings with repeated grease backups may need it yearly. The camera inspection after a cleaning is the best guide for setting the next interval.
Who is responsible for a sewer backup in a rental building?
In most cases the owner or condo corporation is responsible for the building's drains and sewer lateral up to the property line, and tenants or unit owners are responsible for what they put down their own drains. Lease terms, condo declarations and local bylaws vary, so check your documents and your insurance policy.
Can a backwater valve be installed in an existing apartment building?
Yes. It usually means cutting into the basement slab at the main drain, installing the valve and restoring the floor, with a permit where the city requires one. The cost depends on pipe depth, access and how much concrete has to come out.
Get a written scope for your building
Send us the building address, the number of units and any recent drain problems through the quote form, and we will reply with a written scope for the inspection and any cleaning the building needs. We serve multi-unit properties in cities across Canada and the US, including Montréal and Toronto.