Sewer glossary

A–ZTerms

ABS

Acrylonitrile butadiene styrene, a black plastic pipe widely used for drain, waste and vent piping inside Canadian homes since roughly the 1970s.

Access pit

A small excavation that gives equipment entry to a buried pipe, used in trenchless lining and bursting instead of a full-length trench.

Asbestos-cement pipe

Pipe made of cement reinforced with asbestos fibres, used for some mid-century services and mains. Generally stable if undisturbed; cutting or breaking it is specialist work.

Auger

A rotating steel cable with a cutting or retrieving head, fed into a drain to open or pull out a blockage. Also called a snake or drain cable.

Backfill

Soil or granular material placed back into a trench around and over a pipe, compacted in layers to prevent later settlement.

Backwater valve

A one-way valve on the main sanitary drain that closes when sewage flows back from the municipal main, protecting below-grade fixtures.

Bedding

The compacted granular layer a pipe rests on. Poor bedding is a common cause of sags and offset joints.

Belly

A low spot in a sewer line where the pipe has sagged, so water and solids collect instead of flowing. Also called a sag.

Bituminous fibre pipe

Pipe made of wood fibre and pitch, often called Orangeburg, used in some mid-century homes. It deforms with age and usually needs replacement.

Building drain

The lowest horizontal drain inside a building, usually under the basement floor, collecting from the stacks and carrying waste to the building sewer.

Building sewer

The pipe from just outside the foundation to the municipal main or private system. In everyday use, the same as the lateral.

Bursting head

The cone-shaped tool pulled or pushed through an old pipe in pipe bursting, fracturing it outward while drawing new pipe behind.

Bypass pumping

Temporarily pumping wastewater around a pipe section so it can be repaired or replaced while the system stays in service.

Camera inspection

Recording the inside of a drain or sewer with a waterproof camera on a push rod or crawler, with a distance counter and often a locator.

Cast iron pipe

Heavy metal pipe common in older building drains and stacks. It corrodes from the inside, building scale and eventually thinning or cracking.

CCTV inspection

Closed-circuit television inspection; the industry name for a sewer camera inspection, especially with crawler cameras on larger pipe.

CIPP

Cured-in-place pipe: a resin-saturated liner inserted into an existing pipe and hardened with hot water, steam or ultraviolet light to form a new pipe inside it.

Cleanout

A capped fitting that gives access to a drain or sewer for cleaning and cameras without removing fixtures.

Combined sewer

A municipal sewer that carries both sanitary wastewater and stormwater in one pipe, found in older parts of some cities and prone to overload in heavy rain.

Confined space

An enclosed space with limited entry and exit, not designed for continuous occupancy, such as a manhole or sewer. Entry requires testing and trained crews.

Coupling

A fitting that joins two pipe ends, including transitions between different materials. Shielded couplings resist shifting better than plain rubber sleeves.

Descaling

Removing hard mineral or corrosion buildup from inside pipe, often cast iron, with chain knockers, abrasive heads or jetting.

DWV

Drain-waste-vent: the gravity drainage and venting system in a building, as opposed to the pressurised water supply.

Easement

A legal right for someone other than the owner to use part of a property, sometimes covering a shared or utility sewer line.

Ejector pump

A pump that lifts sewage from fixtures below the level of the building drain or municipal main up to where it can flow by gravity.

FOG

Fats, oils and grease: kitchen waste that cools and hardens on pipe walls. Cities regulate it for food businesses through grease interceptor rules.

Fracture

A crack in a pipe that has visibly opened, with pieces separated. More serious than a hairline crack.

Frost depth

How deep the ground freezes in winter. It varies by region and by surface; cleared driveways let frost go deeper than snow-covered lawn.

Grease interceptor

A tank that slows kitchen wastewater so grease floats and solids settle before the flow reaches the sewer. Required for food businesses in many cities.

HDPE

High-density polyethylene pipe, joined by heat fusion into a continuous length; commonly pulled into place in pipe bursting.

Hydro jetting

Cleaning a sewer with high-pressure water through a nozzle whose rear jets pull the hose forward and scour the pipe wall.

Hydrogen sulphide

A toxic, flammable gas with a rotten-egg smell found in sewers. It can dull the sense of smell, so odour is not a reliable warning.

Hydrovac

Excavation that loosens soil with pressurised water and removes the slurry by vacuum, used to expose buried utilities with less strike risk.

Infiltration

Groundwater entering a sewer through cracks, open joints or defects. It adds to flow and can carry soil into the pipe.

Inflow

Stormwater entering a sanitary sewer through direct connections such as downspouts, sump discharges or leaking manhole covers.

Invert

The inside bottom of a pipe. Invert elevations tell designers whether a new service can drain to the main by gravity.

Joint

Where two lengths of pipe meet. Older clay pipe has a joint roughly every metre, which is where roots and offsets usually occur.

LACP

NASSCO's Lateral Assessment Certification Program, a standard coding system for describing defects in service laterals.

Lateral

The pipe connecting a building to the municipal sewer main. Also called the service line or building sewer.

Locate

Marking the position of buried utilities on the ground before digging. Public locates do not include customer-owned lines such as a private sewer lateral.

Main

The municipal sewer pipe, usually under the street or lane, that collects flow from many laterals.

Manhole

An access structure into the municipal sewer system, and a confined space that only trained, equipped crews should enter.

NASSCO

A North American association that sets training and coding standards for assessing and rehabilitating underground pipes, including PACP, LACP and MACP.

Offset joint

A joint where two pipe sections have shifted out of line, leaving a lip that catches debris and can let soil in.

Open cut

Replacing or repairing a sewer by excavating a trench along it, the traditional method that can correct slope and route.

Orangeburg pipe

A common name for bituminous fibre pipe, used in some mid-century homes and prone to deforming and collapsing.

PACP

NASSCO's Pipeline Assessment Certification Program, the standard coding system for defects in sewer mains, widely used by municipalities.

Pipe bursting

A trenchless replacement method that breaks the old pipe outward with a bursting head while pulling a new pipe into its place.

Point repair

A repair confined to one location, by a short sectional liner or a small excavation. Also called a spot repair.

Property line

The legal boundary of a lot. In many Canadian cities it is where the owner's sewer responsibility ends and the municipality's begins.

PVC

Polyvinyl chloride pipe, the most common material for modern residential sewer laterals in Canada, joined with gaskets or solvent cement.

Reinstatement

Reopening a branch connection from inside a pipe after lining, usually with a remote-controlled cutter.

Root intrusion

Tree or shrub roots growing into a pipe through joints or cracks, forming masses that catch debris and block flow.

Sag

Another word for a belly: a section of pipe that has sunk below its intended slope and holds water.

Sanitary sewer

The sewer system that carries household and business wastewater to treatment, separate from storm sewers in most newer areas.

Sectional liner

A short cured-in-place liner installed at a single defect, such as a cracked joint, without lining the whole pipe.

Sewer gas

The mix of gases in sewers, which can include hydrogen sulphide and methane. Water-filled traps keep it out of the house.

Slope

The downward fall of a drain in the direction of flow. The plumbing code sets minimums; too little slope lets solids settle.

Sonde

A small radio transmitter in a camera head or on a cable, detected from the surface to find a pipe's position and approximate depth.

Stack

A vertical drain pipe that collects waste from fixtures on each floor and extends upward through the roof as a vent.

Storm sewer

The system that carries rain and snowmelt from streets, roofs and lots, usually to a waterway without treatment.

Sump pump

A pump in a basement pit that removes groundwater collected by foundation drainage and discharges it away from the house.

Surcharge

When a sewer main carries more flow than its capacity and the water level rises above the pipe, which can push sewage back up laterals.

Trap

A U-shaped bend in a drain that holds a water seal to stop sewer gas entering the building. Unused traps can dry out.

Trenchless

Methods that repair or replace buried pipe with little or no trench, such as cured-in-place lining and pipe bursting.

Vent

Piping open to the outside air, usually through the roof, that lets air into the drainage system so water flows and traps are not siphoned.

Vitrified clay pipe

Fired clay pipe used for many older sewer laterals. Chemically durable but brittle, with frequent joints that roots and ground movement exploit.

Weeping tile

Perforated foundation drainage pipe around a basement footing that collects groundwater, usually draining to a sump or storm system.