OBC On-site Sewage Systems key terms

Ontario statute that authorizes the Building Code, establishes the powers of building officials, and sets out permit, inspection, and enforcement duties for construction, including on-site sewage systems.

Written municipal authorization required before installing or altering a sewage system, issued after review of an application, plans, site information, and required fees, and subject to stated conditions.

Municipal officer appointed under the Building Code Act who administers and enforces the Code, issues permits, conducts inspections, and may order compliance or stop-work action.

Written direction from a building official requiring correction of a contravention of the Building Code Act or Code, such as work without a permit or an unsafe installation.

Part 8 defines this as a system for collecting, treating, or disposing of sewage, including treatment units, tanks, distribution piping, and dispersal works serving a building.

A system that treats sewage in a septic tank or treatment unit and discharges effluent to a leaching bed or filter bed for subsurface disposal in soil.

A watertight tank with no outlet that stores sewage until it is pumped out and hauled away, used where soil or site conditions cannot support on-site treatment and dispersal.

A device or tank, such as a septic tank or packaged aerobic unit, that receives raw sewage and provides primary or secondary treatment before discharge to dispersal works.

A watertight settling tank that separates solids, floats grease and scum, and allows partially clarified liquid to flow onward for further treatment or dispersal.

A removable screening device installed at a septic tank outlet that retains suspended solids, protecting downstream distribution piping and dispersal soil from clogging.

Solids that settle to the tank bottom and buoyant fats and greases that collect at the surface; both accumulate over time and must be removed by pumping.

The accumulated sludge, scum, and liquid removed from a septic or holding tank by a licensed hauler for treatment or disposal at an approved facility.

The volume of effluent applied per unit area of dispersal surface per day, used to size leaching beds and other systems so soil can accept and treat the flow.

The daily sewage volume a system must handle, calculated from fixture units, occupancy, or prescribed per-person or per-bedroom allowances under the Code.

A relative measure of the load a plumbing fixture places on a drainage system, used to total building flow and establish the required sewage system capacity.

The estimated quantity of sewage produced per day used for sizing treatment and dispersal components, derived from occupancy type and Code allowances.

Field investigation of soil texture, depth, permeability, slope, water table, and setbacks that determines whether a site can support a sewage system and what type fits.

An excavated inspection hole used to observe soil horizons, depth to bedrock or water table, and other limiting conditions during a site evaluation.

A measure of how quickly soil absorbs water, determined by a percolation test or estimated from soil texture, used to size dispersal areas.

The highest level groundwater reaches during the year, a limiting condition that constrains separation distances and may rule out conventional subsurface dispersal.

A subsurface dispersal system of perforated distribution pipe laid in gravel or chambers within trenches, where effluent seeps into and is treated by surrounding soil.

A dispersal system using a bed of sand or other filtering medium with distribution piping, providing treatment before effluent reaches underlying soil.

An elevated dispersal system built above natural grade with a sand fill and distribution bed, used where separation to limiting conditions is inadequate at the surface.

Perforated or orifice-equipped piping that spreads effluent evenly along a leaching bed, filter bed, or mound so the soil receives flow uniformly.

Delivering effluent to dispersal works in controlled batches rather than continuously, improving distribution, resting the soil, and supporting even loading.

A pump, often in a pump chamber after the treatment unit, that lifts and delivers measured volumes of effluent to distribution piping on a timed or demand basis.

A watertight basin that receives treated effluent and houses a pump, floats, and controls for delivering sewage to dispersal works or a higher point of discharge.

The minimum required horizontal distance between a sewage system component and a feature such as a well, watercourse, property line, or building.

The required separation distance between system components and other objects or conditions, including wells, trees, slopes, and structures, to protect health and function.

Documentation issued by the building official confirming that completed installation was inspected and complies with the permit and applicable Code requirements.

A drawing recording the actual installed location, dimensions, and components of a sewage system, submitted to document completed work for the permit file.

A written record of site investigation findings, including soil conditions, test pit observations, and constraints, submitted with a permit application to support design decisions.

Periodic checking of tanks, pumps, filters, and dispersal areas to confirm the system operates properly, identify needed pumping or repairs, and prevent premature failure.

An audible or visual warning device that signals high liquid level or pump fault in a pump chamber or treatment unit so occupants can act before sewage backs up.

Wastewater from sinks, showers, baths, and laundry that excludes toilet discharge, sometimes handled by separate systems or reduced-flow designs.

Wastewater containing toilet discharge and often kitchen sink waste, carrying the highest pathogen and organic load and requiring full treatment before dispersal.

Any change to an existing system, such as replacing a tank, extending a bed, or adding fixtures, that may require a new permit and updated design.

Grouping of soil by proportions of sand, silt, and clay, which influences permeability, treatment capacity, and suitability for subsurface dispersal.