Drainage systems: connections, treatment, traps and cleanouts (Plumbing

Last updated October 22, 2026

Values this chapter turns on

max manhole spacing, sewer NPS 24 or smaller: 90 m; max manhole spacing, sewer NPS 24 or smaller
max sewer length from building to first manhole: 75 m; max sewer length from building to first manhole
no-connection zone from the base of a stack: 1.5 m; no-connection zone from the base of a stack
flow a sump must hold if its pump is not automatic: 24 h; flow a sump must hold if its pump is not automatic

Subsections 7.4.1. to 7.4.7. cover connections, treatment of wastes, traps, arrangement and cleanouts. The All Buildings exam leans on commercial items: food equipment drains, interceptors, storm traps, sumps and manholes. Section 7.4. applies to both sanitary and storm drainage systems (OBC Div. B 7.4.1.1.).

Connections to the drainage system

The default is that every fixture connects directly to a sanitary drainage system (OBC Div. B 7.4.2.1.). The exceptions are the exam material:

Item	What is allowed or required
Drinking fountain	indirect to sanitary, or to storm with a backwater valve if the storm system can back up
Drainage pan on a heating or cooling unit	to storm, with a backwater valve if subject to backflow
Floor drain	to storm only where it can receive nothing but clear-water waste or storm water
Clear-water-only fixtures	to storm, or onto a roof
Food display, storage or preparation device, sterilizer, water-cooled or water-heated device, water operated device, water treatment device, relief or overflow from a water or heating system	must be indirectly connected

Two geometry rules matter in taller buildings. Where a stack takes 30 or more fixture units, or takes fixtures from 2 or more storeys, no soil or waste pipe may join the horizontal drain (or a horizontal offset) within 1.5 m, measured horizontally, of the bottom of that stack. Where a pipe serving more than one clothes washer turns more than 45°, suds create pressure zones: no connection within 40 times the pipe size (or 2.44 m vertical, whichever is less) before the turn, and within 10 times the pipe size after it.

Indirect food equipment drains can be grouped. Drains from food devices and sterilizers may run to a common pipe that ends in an air break over a fixture connected to the sanitary system, and that pipe must go through the roof if fixtures on 3 or more storeys connect to it (OBC Div. B 7.4.2.3.). A rainwater tank overflow connects to storm through an air break or a backwater valve (OBC Div. B 7.4.2.2.).

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Fixture location restrictions

No indirect connection or overflow-prone trap in a crawl space or other unfrequented area (7.4.3.2.).
A floor drain in an oil transformer vault, high voltage room, or room where flammable, dangerous or toxic chemicals are stored or handled is not connected to a drainage system at all (7.4.3.4.).
Equipment discharging organic solids (a garbage grinder, for example) cannot be upstream of a grease interceptor unless a food scrap interceptor is installed ahead of it (7.4.3.3.).

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Treatment: interceptors and neutralizing tanks

Interceptors are in OBC Div. B 7.4.4.3..

Situation	Requirement
Fixture discharging fats, oils or grease in a food preparation area (not in a residential suite)	grease interceptor, as close as possible to the fixtures
Service station, repair shop, garage where vehicles are repaired, lubricated or maintained	oil interceptor
Industrial use of oily or flammable liquids	engineered oil interceptor
Hydraulic elevator pit, parking lot, car wash, parking-only garage	no oil interceptor required
Sand, grit or similar	an interceptor designed to trap it
Head over 5 feet on a grease or oil interceptor	a secondary flow control in addition to the internal one

Flow through a grease interceptor must not exceed its rating. For each fixture, take 0.75 times its volume in litres and divide by the drain down time (60 or 120 seconds), add them up, then add any pump discharge in L/s.

Corrosive or acid waste goes to a neutralizing or dilution tank that connects to the sanitary system through a trap or an indirect connection, and the tank needs a way to neutralize the liquid (OBC Div. B 7.4.4.4.).

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Traps

Each fixture gets its own trap (OBC Div. B 7.4.5.1.), with exceptions for multi-compartment sinks and trays, 2 similar fixtures in one room, and a group of floor drains, hub drains, shower drains, washing machines or laboratory sinks in one room, if they cannot receive food or organic matter. An interceptor with at least a 38 mm water seal can act as the trap.

Storm drainage has its own trap rule (OBC Div. B 7.4.5.2.). Where storm piping connects to a combined sewer, a trap is needed between each opening and the sewer. A leader top needs no trap if the roof is used only for weather protection, the opening is at least 1 m above or 3.5 m in any other direction from air inlets, openable windows and doors, and at least 1.8 m from a property line. A storm floor drain is trapped, one trap may serve all floor drains in the room, and that trap needs no vent.

A building trap needs a cleanout on its upstream side directly over the trap, sits upstream of the building cleanout, and is either inside near where the drain leaves the building or outside in a manhole (7.4.5.4.). Floor drain and hub drain trap seals are maintained by a trap seal primer, an indirectly connected drinking fountain or an equal means; a primer line is at least 3/8 in. inside diameter (7.4.5.5.).

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Arrangement: sumps and backwater valves

Only piping too low to drain by gravity goes to a sump (OBC Div. B 7.4.6.3.). A sanitary sump is water- and air-tight and vented. If the pump is not automatic, the sump holds at least 24 hours of flow.
A sanitary pumped discharge has a union, a backwater valve and a shut-off valve, in that order in the direction of flow. A storm sump discharge has a union and a check valve pumped to above grade, or a union, check valve and shut-off valve.
A backwater valve that stops air circulation is not allowed in a building drain or sewer. A "normally open" valve to one of the listed CSA standards may be used in a building drain serving not more than one dwelling unit (OBC Div. B 7.4.6.4.).
Where a drain may back up, fixtures below the adjoining street level get a backwater valve on their fixture drain; several fixtures on one storey on the same branch can share one on the branch.

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Cleanouts and manholes

OBC Div. B 7.4.7.1. requires cleanouts that allow cleaning of the whole system, plus specific ones: over every running trap, at or within 1 m of the bottom of an interior leader, at or within 3 m of the bottom of a stack (or on the Y fitting at its base), downstream of an interceptor, at every change over 45° on an indirect food drain, and on a kitchen sink trap arm. The building drain gets an NPS 4 or larger cleanout near where it leaves the building. On a building sewer of NPS 8 or larger, a required cleanout must be a manhole. A building sewer runs straight between cleanouts, except that pipes up to NPS 6 may bend not more than 5° every 3 m, or use fittings totalling 45°.

Cleanout spacing on horizontal pipe comes from Table 7.4.7.2.: read the pipe size row, then the one-way or two-way rodding column (two-way is double).

Building sewer limits from OBC Div. B 7.4.7.2.:

Item	Limit
Manhole spacing, sewer NPS 24 or less	90 m
Manhole spacing, sewer over NPS 24	150 m
Building to first manhole	75 m developed length
Building to another building sewer, joined without a manhole	30 m

Manholes go at all junctions and changes of grade, size or alignment on an NPS 8 or larger sanitary building sewer; on storm sewers of NPS 8 or more, at changes of grade, size or alignment. A manhole is at least 1.2 m across (the top 1.5 m may taper to 600 mm), has a ladder where deeper than 1 m, is channelled if sanitary, and inside a building has an airtight cover and a vent to outside (OBC Div. B 7.4.7.3.).

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Common traps

Car washes and parking-only garages do not need an oil interceptor; repair garages do.
The 1.5 m no-connection zone is measured horizontally from the stack base and applies at 30 fixture units or 2 storeys.
Manhole spacing (90 m or 150 m) and building-to-first-manhole length (75 m) are different numbers.
The pumped sanitary discharge order is union, backwater valve, shut-off valve. Storm sumps use a check valve instead.

Chapter review

Chapter at a glance

One line per section: the idea to carry into the exam. Then the answers that most often catch candidates out.

Chapter at a glance: the key idea in each section
Section	Key idea
Connections to the drainage system	The default is that every fixture connects directly to a sanitary drainage system.
Treatment: interceptors and neutralizing tanks	Flow through a grease interceptor must not exceed its rating.
Traps	Each fixture gets its own trap, with exceptions for multi-compartment sinks and trays, 2 similar fixtures in one room, and a group of floor drains, hub drains, shower drains…
Cleanouts and manholes	Cleanout spacing on horizontal pipe comes from: read the pipe size row, then the one-way or two-way rodding column (two-way is double).

Connections to the drainage system
The default is that every fixture connects directly to a sanitary drainage system.
Treatment: interceptors and neutralizing tanks
Flow through a grease interceptor must not exceed its rating.
Traps
Each fixture gets its own trap, with exceptions for multi-compartment sinks and trays, 2 similar fixtures in one room, and a group of floor drains, hub drains, shower drains…
Cleanouts and manholes
Cleanout spacing on horizontal pipe comes from: read the pipe size row, then the one-way or two-way rodding column (two-way is double).

Usual exam traps

Car washes and parking-only garages do not need an oil interceptor; repair garages do.
The 1.5 m no-connection zone is measured horizontally from the stack base and applies at 30 fixture units or 2 storeys.
Manhole spacing (90 m or 150 m) and building-to-first-manhole length (75 m) are different numbers.
The pumped sanitary discharge order is union, backwater valve, shut-off valve. Storm sumps use a check valve instead.

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Code cited in this chapter

Based on the official 2024 Building Code Compendium on ontario.ca.

OBC Div. B 7.4.1.1. General
(1)This Section applies to sanitary drainage systems and storm drainage systems.
Open OBC Div. B 7.4.1.1. in the code viewer
OBC Div. B 7.4.2.1. Connections to Sanitary Drainage Systems
(1)Fixtures shall be directly connected to a sanitary drainage system, except that
(a)drinking fountains are permitted to be
(i)indirectly connected to a sanitary drainage system, or
(ii)connected to a storm drainage system, provided that where the system is subject to backflow, a backwater valve is installed in the fountain fixture drain,
(b)drainage pans on heating/cooling units are permitted to be connected to a storm drainage system, provided that where the system is subject to backflow, a backwater valve is installed,
(c)a floor drain is permitted to be connected to a storm drainage system, provided it is located where it can receive only clear-water waste or storm water,
(d)fixtures or appliances that discharge only clear-water waste are permitted to be connected to a storm drainage system or be drained onto a roof, and,
(e)the following devices shall be indirectly connected to a drainage system:
(i)a device for the display, storage, preparation or processing of food or drink,
(ii)a sterilizer,
(iii)a device that uses water as a cooling or heating medium,
(iv)a water operated device,
(v)a water treatment device,
(vi)a drain or overflow from a water system or a heating system.
(2)The connection of a soil or waste pipe to a nominally horizontal soil or waste pipe or to a nominally horizontal offset in a soil or waste stack shall be respectively at least 1.5 m measured horizontally from the bottom of a soil or waste stack or from the bottom of the upper vertical section of the soil or waste stack that,
(a)receives a discharge of 30 or more fixture units, or
(b)receives a discharge from fixtures located on 2 or more storeys.
(3)No other fixture shall be connected to a lead bend or stub that serves a water closet.
(4)Where a change in direction of more than 45° occurs in a soil or waste pipe that serves more than one clothes washer, and in which pressure zones are created by detergent suds, no other soil or waste pipe shall be connected to it within a length less than
(a)40 times the nominal pipe size of the soil or waste pipe or 2.44 m maximum vertical, whichever is less, before changing direction, and
(b)10 times the nominal pipe size of the nominally horizontal soil or waste pipe after changing direction. (See Note A-7.4.2.1.(4))
(5)Where a vent pipe is connected into a suds pressure zone referred to in Sentence (4), no other vent pipe shall be connected to that vent pipe within the height of the suds pressure zone. (See Note A-7.4.2.1.(4))
Open OBC Div. B 7.4.2.1. in the code viewer
OBC Div. B 7.4.2.3. Direct Connections
(1)Two or more fixture outlet pipes that serve outlets from a single fixture that is listed in Clause 7.4.2.1.(1)(d) may be directly connected to a branch that
(a)has a nominal pipe size of not less than NPS 1¼, and
(b)is terminated above the flood level rim of a directly connected fixture with a minimum diameter waste of 1½ in. to form an air break.
(2)Fixture drains from fixtures that are listed in Subclauses 7.4.2.1.(1)(e)(i) and (ii) may be directly connected to a pipe that
(a)is terminated to form an air break above the flood level rim of a fixture that is directly connected to a sanitary drainage system, and
(b)is extended through the roof when fixtures that are on 3 or more storeys are connected to it.
(3)Fixture drains from fixtures that are listed in Subclauses 7.4.2.1.(1)(d)(iii) to (vi) may be directly connected to a pipe that,
(a)is terminated to form an air break above the flood level rim of a fixture that is directly connected to a storm drainage system, and
(b)is extended through the roof when fixtures that are on 3 or more storeys are connected to it.
(4)Every waste pipe carrying waste from a device for the display, storage, preparation or processing of food or drink shall be trapped and have a minimum diameter equal to the diameter of the drain outlet from the device.
Open OBC Div. B 7.4.2.3. in the code viewer
OBC Div. B 7.4.2.2. Connection of Overflows from Rainwater Tanks
(1)Where an overflow from a rainwater tank is connected to a storm drainage system, it shall be connected by
(a)an air break, or
(b)a backwater valve installed on the storm drainage pipe before the connection to the storm building drain.
Open OBC Div. B 7.4.2.2. in the code viewer
OBC Div. B 7.4.3.2. Restricted Locations of Indirect Connections and Traps
(1)Indirect connections or any trap that may overflow shall not be located in a crawl space or any other unfrequented area.
Open OBC Div. B 7.4.3.2. in the code viewer
OBC Div. B 7.4.3.4. Fixtures Located in Chemical Storage Locations
(1)A floor drain or other fixture located in an oil transformer vault, a high voltage room or any room where flammable, dangerous or toxic chemicals are stored or handled shall not be connected to a drainage system.
Open OBC Div. B 7.4.3.4. in the code viewer
OBC Div. B 7.4.3.3. Equipment Restrictions Upstream of Grease Interceptors
(1)Except as provided in Sentence (2), equipment discharging waste with organic solids shall not be located upstream of an interceptor. (See Note A-7.4.3.3.(1))
(2)If a food scrap interceptor has been installed upstream of the grease interceptor, equipment discharging waste with organic solids may discharge through a grease interceptor.
Open OBC Div. B 7.4.3.3. in the code viewer
OBC Div. B 7.4.4.3. Interceptors
(1)Except for suites of residential occupancy, where a fixture discharges sewage that includes fats, oils or grease and is located in an area where food is cooked, processed or prepared, it shall discharge through a grease interceptor. (See Note A-7.4.4.3.(1))
(2)Except as provided in Sentence (3), oil interceptors shall be provided as follows:
(a)service stations, repair shops and garages or any establishment where motor vehicles are repaired, lubricated or maintained shall be provided with an oil interceptor, and
(b)establishments which use oily or flammable liquids or have such wastes as a result of an industrial process shall be provided with an engineered oil interceptor.
(2.1)Oil interceptors are not required for a drain in a hydraulic elevator pit, parking lot, car wash or a garage used exclusively as a motor vehicle parking area.
(3)Where a fixture discharges sand, grit or similar materials, an interceptor designed for the purpose of trapping such discharges shall be installed.
(4)Interceptors shall have sufficient capacity to perform the service for which it is provided.
(5)An on-site constructed interceptor shall be constructed to the requirements of a manufactured interceptor.
(6)A grease interceptor shall be located as close as possible to the fixture or fixtures it serves.
(7)The flow rate through a grease interceptor shall not exceed its rated capacity and the flow rate shall be determined using the following:
Q = (∑_1^N(0.75V/DDT)) + PD
where:
Q is the flow rate to a grease interceptor in L/s.
V is the volume of the fixture in L.
DDT is the drain down time, 60 or 120 seconds.
PD is any pump discharge in L/s.
N is the number of fixtures to go through the interceptor.
(8)All grease and oil interceptors shall have an internal flow control and, where the head will exceed five feet, a secondary flow control shall be required.
(9)Floor drains that conform to Sentence 7.4.5.1.(3) are not required to be separately trapped and vented, and may be gang trapped when discharging through an oil interceptor.
Open OBC Div. B 7.4.4.3. in the code viewer

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OBC Div. B 7.4.4.4. Neutralizing and Dilution Tanks
(1)Where a fixture or equipment discharges corrosive or acid waste, it shall discharge into a neutralizing or dilution tank that is connected to the sanitary drainage system through
(a)a trap, or
(b)an indirect connection.
(See Note A-7.4.4.(1))
(2)Neutralizing or dilution tanks shall have a method for neutralizing the liquid.
Open OBC Div. B 7.4.4.4. in the code viewer
OBC Div. B 7.4.5.1. Traps for Sanitary Drainage Systems
(1)Except as provided in Sentences (2) to (5) and Article 7.4.5.2., fixtures shall be protected by a separate trap.
(2)One trap is permitted to protect
(a)all the trays or compartments of a 2- or 3- compartment sink,
(b)a 2- or 3- compartment laundry tray, or
(c)2 similar type single compartment fixtures located in the same room.
(3)One trap is permitted to serve a group of floor drains and hub drains, a group of shower drains, a group of washing machines or a group of laboratory sinks if the fixtures
(a)are in the same room, and
(b)are not located where they can receive food or other organic matter.
(4)Reserved.
(5)An interceptor with an effective water seal of not less than 38 mm is permitted to serve as a trap. (See Note A-7.4.5.1.(5))
(6)Where a domestic dishwashing machine equipped with a drainage pump discharges through a direct connection into the fixture outlet pipe of an adjacent kitchen sink or disposal unit, the pump discharge line shall rise as high as possible to just under the counter and connect
(a)on the inlet side of the sink trap by means of a Y fitting, or
(b)to the disposal unit.
Open OBC Div. B 7.4.5.1. in the code viewer
OBC Div. B 7.4.5.2. Traps for Storm Drainage Systems
(1)Where a storm drainage system is connected to a combined building sewer or a public combined sewer, a trap shall be installed between any opening in the system and the drain or sewer, except that no trap is required if the opening is the upper end of a leader that terminates
(a)at a roof that is used only for weather protection,
(b)not less than 1 m above or not less than 3.5 m in any other direction from any air inlet, openable window or door, and
(c)not less than 1.8 m from a property line. (See Note A-7.4.5.2.(1))
(2)A floor drain that drains to a storm drainage system shall be protected by a trap that
(a)is located between the floor drain and a leader, storm building drain or storm building sewer,
(b)may serve all floor drains located in the same room, and
(c)need not be protected by a vent pipe.
Open OBC Div. B 7.4.5.2. in the code viewer
OBC Div. B 7.4.5.4. Location and Cleanout for Building Traps
(1)Where a building trap is installed, it shall
(a)be provided with a cleanout fitting on the upstream side of and directly over the trap,
(b)be located upstream of the building cleanout, and
(c)be located
(i)inside the building as close as practical to the place where the building drain leaves the building, or
(ii)outside the building in a manhole.
Open OBC Div. B 7.4.5.4. in the code viewer
OBC Div. B 7.4.5.5. Trap Seals
(1)Provision shall be made for maintaining the trap seal of a floor drain or a hub drain by
(a)the use of a trap seal primer,
(b)using the drain as a receptacle for an indirectly connected drinking fountain, or
(c)other equally effective means.
(2)Where a mechanical device is installed to furnish water to a trap, the pipe or tube conveying water from the device to the trap shall be at least 3/8 in. inside diameter.
Open OBC Div. B 7.4.5.5. in the code viewer
OBC Div. B 7.4.6.3. Sumps or Tanks
(1)Only piping that is too low to drain into a building sewer by gravity shall be drained to a sump or receiving tank.
(2)Where the sump or tank receives sanitary sewage, it shall be water- and air-tight and shall be vented.
(3)Where the sump or tank receives subsurface water from a subsoil drainage pipe, it shall be provided with a water-and air-tight cover.
(4)Equipment such as a pump or ejector that can lift the contents of the sump or tank and discharge it into the sanitary building drain or sanitary building sewer shall be installed.
(5)Where the equipment does not operate automatically, the capacity of the sump shall be sufficient to hold at least a 24 hour accumulation of liquid.
(6)Where there is a building trap, the discharge pipe from the equipment shall be connected to the sanitary building drain downstream of the trap.
(7)The discharge pipe from every pumped sump shall be equipped with a union, a backwater valve and a shut-off valve installed in that sequence in the direction of discharge.
(8)The discharge piping from a pump or ejector shall be sized for optimum flow velocities at pump design conditions.
(9)The discharge pipe from every pumped storm sewage sump shall be equipped with
(a)a union and a check valve installed in that sequence in the direction of discharge and pumped to above grade level, or
(b)a union, a check valve and a shut-off valve installed in that sequence in the direction of discharge.
Open OBC Div. B 7.4.6.3. in the code viewer
OBC Div. B 7.4.6.4. Protection from Backflow
(1)Except as permitted in Sentence (2), a backwater valve that would prevent free circulation of air shall not be installed in a building drain or in a building sewer.
(2)A backwater valve may be installed in a building drain provided that,
(a)it is a "normally open" design conforming to,
(i)CAN/CSA-B70, "Cast Iron Soil Pipe, Fittings, and Means of Joining",
(ii)CAN/CSA-B181.1, "Acrylonitrile-Butadiene-Styrene (ABS) Drain, Waste, and Vent Pipe and Pipe Fittings",
(iii)CAN/CSA-B181.2, "Polyvinylchloride (PVC) and Chlorinated Polyvinylchloride (CPVC) Drain, Waste, and Vent Pipe and Pipe Fittings", or
(iv)CAN/CSA-B182.1, "Plastic Drain and Sewer Pipe and Pipe Fittings", and
(b)it does not serve more than one dwelling unit.
(3)Except as provided in Sentences (4) and (5), where a building drain or a branch may be subject to backflow,
(a)a backwater valve shall be installed on every fixture drain connected to it when the fixture is located below the level of the adjoining street, or
(b)a backwater valve shall be installed to protect fixtures which are below the upstream sanitary manhole cover when a residential building is served by a public sanitary sewer.
(4)Where more than one fixture is located on a storey and all are connected to the same branch, the backwater valve may be installed on the branch.
(5)A subsoil drainage pipe that drains into a sanitary drainage system that is subject to surcharge shall be connected in such a manner that sewage cannot back up into the subsoil drainage pipe.
Open OBC Div. B 7.4.6.4. in the code viewer
OBC Div. B 7.4.7.1. Cleanouts for Drainage Systems
(1)Sanitary drainage systems and storm drainage systems shall be provided with cleanouts that will permit cleaning of the entire system. (See Note A-7.4.7.1.(1))
(2)A cleanout fitting shall be provided on the upstream side and directly over every running trap.
(3)Interior leaders shall be provided with a cleanout fitting at the bottom of the leader or not more than 1 m upstream from the bottom of the leader.
(4)Where a cleanout is required on a building sewer of NPS 8 or larger, it shall be a manhole.
(5)A building sewer shall not change direction or slope between the building and public sewer or between cleanouts, except that pipes not more than NPS 6 may change direction
(a)by not more than 5° every 3 m, or
(b)by the use of fittings with a cumulative change in direction of not more than 45°.
(6)Building drains shall be provided with a cleanout fitting of NPS 4 or larger that is located as close as practical to the place where the building drain leaves the building. (See Note A-7.4.7.1.(6))
(7)Stacks shall be provided with a cleanout fitting
(a)at the bottom of the stack,
(b)not more than 3 m upstream of the bottom of the stack, or
(c)on a Y fitting connecting the stack to the building drain or branch.
(8)A cleanout shall be provided to permit the cleaning of the piping immediately downstream of an interceptor.
(9)Every indirect drainage pipe carrying waste from a food receptacle shall have a cleanout access at every change of direction of more than 45°.
(10)A cleanout shall be installed on a trap arm serving a kitchen sink as close as practical to the trap outlet and shall be readily accessible.
Open OBC Div. B 7.4.7.1. in the code viewer
OBC Div. B Table 7.4.7.2. Permitted Size and Spacing of Cleanouts
Table 7.4.7.2. — Permitted Size and Spacing of Cleanouts Forming Part of Sentence 7.4.7.2.(1) Nominal Pipe Size of Drainage Pipe, NPS | Minimum Nominal Pipe Size of Cleanout, NPS | Maximum Spacing, m for One-Way Rodding | Maximum Spacing, m for Two-Way Rodding less than 3 | Same NPS as drainage pipe | 7.5 | 15 3 and 4 | 3 | 15 | 30 over 4 | 4 | 26 | 52
Open OBC Div. B Table 7.4.7.2. in the code viewer
OBC Div. B 7.4.7.2. Size and Spacing of Cleanouts
(1)Except as provided in Sentences (2), (3) and 7.4.7.1.(6), the nominal pipe size and spacing of cleanouts in nominally horizontal pipes of a drainage system shall conform to Table 7.4.7.2.
(2)The spacing between manholes serving a building sewer
(a)of NPS 24 or less shall not exceed 90 m, and
(b)over NPS 24 shall not exceed 150 m.
(3)The developed length of a building sewer between the building and the first manhole to which the building sewer connects shall not exceed 75 m.
(4)Where a building sewer connects to another building sewer other than by a manhole, the developed length between the building and the building sewer to which it connects shall not exceed 30 m.
(5)Cleanouts that allow rodding in one direction only shall be installed to permit rodding in the direction of flow.
(6)Manholes shall be located at all junctions and all changes in grade, size or alignment (except for curvilinear alignment) on a sanitary building sewer that is NPS 8 or larger.
(7)Manholes shall be located at changes of grade, size or alignment (except for curvilinear alignment) on a storm building sewer or exterior storm drainage pipe that is NPS 8 or larger.
Open OBC Div. B 7.4.7.2. in the code viewer
OBC Div. B 7.4.7.3. Manholes
(1)A manhole, including the cover shall be designed to support all loads imposed upon it.
(2)A manhole shall be provided with
(a)a cover that provides an airtight seal if located within a building,
(b)a rigid ladder of a corrosion-resistant material where the depth exceeds 1 m, and
(c)a vent to the exterior if the manhole is located within a building.
(3)A manhole shall have a minimum horizontal dimension of 1.2 m, except that the top 1.5 m may be tapered from 1.2 m down to a minimum of 600 mm at the top.
(4)A manhole in a sanitary drainage system shall be channeled to direct the flow of effluent.
Open OBC Div. B 7.4.7.3. in the code viewer