Division B
Acceptable Solutions
Part 2 — Plumbing Systems
Section 2.4. Drainage Systems
2.4.1. Application
2.4.1.1. General
This Section applies to sanitary drainage systems, storm drainage systems, combined building drains or combined building sewers. 2.4.2. Connections to Drainage Systems
2.4.2.1. Connections to Sanitary Drainage Systems
Every fixture shall be directly connected to a sanitary drainage system, except that
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 not less than 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
No other fixture shall be connected to a lead bend or stub that serves a water closet.

Where a change in direction of more than 45º 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
40 times the size of the soil-or-waste pipe or 2.44 m maximum vertical, whichever is less, before changing direction, and

Where a vent pipe is connected into the 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 Appendix Note Appendix Note A-2.4.2.1.(4) in Appendix A.)
2.4.2.2. Connection of Overflows from Rainwater Tanks
2.4.2.3. Direct Connections
Two or more fixture outlet pipes that serve outlets from a single fixture that is listed in Clause 2.4.2.1.(1)(e) may be directly connected to a branch that
Fixture drains from fixtures that are listed in Subclauses (1)(e)(i) and (e)(ii) may be directly connected to a pipe that
Fixture drains from fixtures that are listed in Subclauses (1)(e)(iii) to (e)(vi) may be directly connected to a pipe that2.4.3. Location of Fixtures
2.4.3.1. Urinals
Book I (General) of this Code
.) 
2.4.3.2. Restricted Locations of Indirect Connections and Traps
Indirect connections or any trap that may overflow shall not be located in a crawl space or any other unfrequented
area.
2.4.3.3. Equipment Restrictions Upstream of Grease Interceptors
Except as provided in Sentence (2), equipment discharging waste with organic solids shall not be located upstream of a grease interceptor. (See Appendix A.)2.4.3.4. Fixtures Located in Chemical Storage Locations
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. 2.4.3.5. Macerating Toilet Systems
A macerating toilet system shall only be installed where no connection to a gravity sanitary drainage system is available. 2.4.3.6. Drains Serving Elevator Pits
Where a drain is provided in an elevator pit2.4.4. Treatment of Sewage and Wastes
2.4.4.1. Sewage Treatment
Where a fixture or equipment discharges sewage or waste that may damage or impair the sanitary drainage system or the functioning of a public or private sewage disposal system, provision shall be made for treatment of the sewage or waste before it is discharged to the sanitary drainage system.
2.4.4.2. Cooling of Hot Water or Sewage
Where a fixture discharges sewage or clear-water waste that is at a temperature above 75°C, provision shall be made for cooling of the waste to
75°C or less before it is discharged to the drainage system. 2.4.4.3. Interceptors
Where a fixture discharges sewage that includes fats, oils or grease and is located in a public kitchen, in a restaurant or in a care or detention occupancy, it shall discharge through a grease interceptor. (See Appendix A.)
Where the discharge from a fixture may contain oil or gasoline, an oil interceptor shall be installed. (See Article 2.5.5.2. for venting requirements for oil interceptors.)
Where a fixture discharges sand, grit or similar materials, an interceptor designed for the purpose of trapping such discharges shall be installed.
Every interceptor shall have sufficient capacity to perform the service for which it is provided.
2.4.4.4. Neutralizing and Dilution Tanks
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 through2.4.5. Traps
2.4.5.1. Traps for Sanitary Drainage Systems
Except as provided in Sentences (2), (3), (4) and (5) and in Article 2.4.5.2., every fixture shall be protected by a separate trap.
One trap may protect
One trap may serve a group of floor drains or shower drains, a group of washing machines or a group of laboratory sinks if the fixtures
An indirectly connected fixture that can discharge only clear-water waste other than a drinking fountain need not be protected by a trap. (See Clause 2.4.2.1.(1)(e) for indirect connections.)
An interceptor with an effective water seal of not less than 38 mm may serve as a trap. (See Appendix A.)
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 connect2.4.5.2. Traps for Storm Drainage Systems
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 sewer, except that no
trap is required if the opening is the upper end of a leader that terminates
A floor drain that drains to a storm drainage system shall be protected by a trap that
Where freezing conditions could cause storm drainage systems to freeze due to air circulation within the piping, a trap with a cleanout shall be installed in a heated location. 2.4.5.3. Connection of Subsoil Drainage Pipe to a Sanitary Drainage System
Where a subsoil drainage pipe is connected to a sanitary drainage system, the connection shall be made on the upstream side of a trap with a cleanout or a trapped sump. (See Appendix A.) 2.4.5.4. Location and Cleanout for Building Traps
Where a building trap is installed it shall2.4.5.5. Trap Seals
Provision shall be made for maintaining the trap seal of a floor drain by2.4.6. Arrangement of Drainage Piping
2.4.6.1. Separate Systems
There shall be no unused open ends in a drainage system and dead ends shall be so graded that water will not collect in them.
2.4.6.2. Location of Soil-or-Waste Pipes
A soil-or-waste pipe shall not be located directly above2.4.6.3. Sumps or Tanks
(See Appendix A.)
Piping that is too low to drain into a building sewer by gravity shall be drained to a sump or receiving tank.
Where the sump or tank receives sewage, it shall be water- and air-tight and shall be vented.
Equipment such as a pump or ejector that can lift the contents of the sump or tank and discharge it into the building drain or building sewer shall be installed.
Where the equipment does not operate automatically, the capacity of the sump shall be sufficient to hold at least a 24 h accumulation of liquid.
Where there is a building trap, the discharge pipe from the equipment shall be connected to the building drain downstream of the trap.
backwater valve
and a shut-off valve installed in that sequence in the direction of discharge. 
The discharge piping from a pump or ejector shall be sized for optimum flow velocities at pump design conditions.
2.4.6.4. Protection from Backflow
Except as permitted in Sentence (2), a backwater valve or a gate valve that would prevent the free circulation of air shall not be installed
in a building drain or in a building sewer. (See Appendix A.)
A backwater valve may be installed in a building drain provided that
Except as provided in Sentences (4), (5) and (6), where a building drain or a branch may be subject to backflow, a gate valve or a backwater valve shall be installed on every fixture drain connected to them when the fixture is located below the level of the adjoining street.
Where the fixture is a floor drain, a removable screw cap may be installed on the upstream side of the trap.
Where more than one fixture is located on a storey and all are connected to the same branch, the gate valve or backwater valve may be installed on the branch.
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. (See Appendix A.) 2.4.6.5. Mobile Home Sewer Service
A building sewer intended to serve a mobile home shall be2.4.7. Cleanouts
2.4.7.1. Cleanouts for Drainage Systems
Every sanitary drainage system and storm drainage system shall be provided with cleanouts that will permit cleaning of the entire system. (See Appendix A.)
Every interior leader shall be provided with a cleanout fitting at the bottom of the leader or not more than 3 m upstream from the bottom of the leader.
Where a cleanout is required on a building sewer 8 inches or larger in size, it shall be a manhole.
A building sewer shall not change direction or slope between the building and public sewer or between cleanouts, except that pipes not more than 6 inches in size may change direction
Every building drain shall be provided with a cleanout fitting that is located as close as practical to the place where the building drain leaves the building. (See Appendix A.)
Every soil-or-waste stack shall be provided with a cleanout fitting
Cleanouts shall be installed so that the cumulative change in direction is not more than 90° between cleanouts in a drip pipe from a food receptacle or in a fixture drain serving a kitchen sink. (See Appendix A.) 2.4.7.2. Size and Spacing of Cleanouts
Except as provided in Sentences (2) and (3), the size and spacing of cleanouts in nominally horizontal pipes of a drainage system shall conform to Table 2.4.7.2.| Table 2.4.7.2. Permitted Size and Spacing of Cleanouts Forming part of Sentence 2.4.7.2.(1) | |||
|
Size of Drainage Pipe, inches |
Maximum Spacing, m | ||
| One-Way Rodding | Two-Way Rodding | ||
|
less than 3 |
Same size as drainage pipe |
7.5 | 15 |
| 3 and 4 |
Same size as drainage pipe |
15 | 30 |
| over 4 | 4 | 26 | 52 |
The spacing between manholes serving a building sewer
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.
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.
Cleanouts that allow rodding in one direction only shall be installed to permit rodding in the direction
of flow.
2.4.7.3. Manholes
A manhole shall be provided with
A manhole shall have a minimum horizontal dimension of 1 m, except that the top 1.5 m may be tapered from 1 m down to a minimum of 600 mm at
the top.
A manhole in a sanitary drainage system shall be channeled to direct the flow of effluent. 2.4.7.4. Location of Cleanouts
Cleanouts and access covers shall be located so that their openings are readily accessible for drain
cleaning purposes.
A cleanout shall not be
The piping between a cleanout fitting and the drainage piping or vent piping that it serves shall not change
direction by more than 45°.
Cleanouts serving fixtures in health care facilities, mortuaries, laboratories and similar occupancies, where contamination by body fluids is likely, shall be located a minimum of 150
mm above the flood level rim of the fixture. 2.4.8. Minimum Slope and Length of Drainage Pipes
2.4.8.1. Minimum Slope
Except as provided in Articles 2.4.10.8. and 2.4.10.9., every drainage pipe that has a size of 3 inches or less shall have a downward slope in the direction of flow of at least 1 in 50. (See Appendix A.) 2.4.8.2. Length of Fixture Outlet Pipes
Except for fixture outlet pipes installed in conformance with Sentence 2.4.5.1.(3), the developed length of every fixture outlet pipe shall not exceed 1 200 mm. (See Appendix A.) 2.4.9. Size of Drainage Pipes
2.4.9.1. No Reduction in Size
A soil-or-waste pipe shall be of a size not less than the size of2.4.9.2. Serving Water Closets
The size of every drainage pipe that serves a water closet shall be not less than 3 inches.
The size of every branch or building drain downstream of the third water closet fixture drain connection shall be not less than 4 inches.
The size of every soil-or-waste stack that serves more than 6 water closets shall be not less than 4 inches.
2.4.9.3. Size of Fixture Outlet Pipes
Except as provided in Sentence (2), the size of every fixture outlet pipe shall conform to Table 2.4.9.3.
The part of the fixture outlet pipe that is common to 3 compartments of a sink shall be one size larger than the largest fixture outlet pipe of the compartments that it serves. (See Appendix A.) | Table 2.4.9.3. Minimum Permitted Size of Fixture Outlet Pipe and Hydraulic Loads for Fixtures(1) Forming part of Sentences 2.4.9.3.(1) and 2.4.10.2.(1) | ||
|
Minimum Size of Fixture Outlet Pipe, inches |
Hydraulic Load, fixture units | |
| Autopsy table | 1½ | 2 |
| (a) with flush tank | n/a | 6 |
| (b) with direct flush valve | n/a | 8 |
| Bathtub (with or without shower) | 1½ | 1½ |
| Bath: foot, sitz or slab | 1½ | 1½ |
| Beer cabinet | 1½ | 1½ |
| Bidet | 1¼ | 1 |
| Clothes washer | ||
| (a) domestic(1) | n/a |
|
| (b) commercial | n/a |
2 with
|
| Dental unit or cuspidor | 1¼ | 1 |
| Dishwasher | ||
| (a) domestic type | 1½ | 1½ no load when connected to garbage grinder or domestic sink |
| (b) commercial type | 2 | 3 |
| Drinking fountain | 1¼ | ½ |
|
Floor drain(2) |
2 |
2 with 2-in. trap |
|
3 with 3-in. trap |
||
| Garbage grinder, commercial type | 2 | 3 |
| Icebox | 1¼ | 1 |
| Laundry tray | ||
| (a) single or double units or 2 single units with common trap | 1½ | 1½ |
| (b) 3 compartments | 1½ | 2 |
| Lavatory | ||
| (a) barber or beauty parlor | 1½ | 1½ |
| (b) dental | 1¼ | 1 |
| (c) domestic type, single or | 1¼ |
1 with 1¼-in. trap |
| 2 single with common trap |
1½ with 1½-in. trap |
|
| (d) multiple or industrial type | 1½ |
according to Table 2.4.10.2. |
|
|
|
|
| Potato peeler | 2 | 3 |
| Shower drain | ||
| (a) from 1 head | 1½ | 1½ |
| (b) from 2 or 3 heads | 2 | 3 |
| (c) from 4 to 6 heads | 3 | 6 |
| Sink | ||
| (a) domestic and other small types with or without garbage grinders, single, double or 2 single with a common trap | 1½ | 1½ |
| (b) Other sinks | 1½ |
1½ with 1½-in. trap |
|
2 with 2-in. trap |
||
|
3 with 3-in. trap |
||
| Urinal | ||
| (a) pedestal, siphon-jet or blowout type | 2 | 4 |
| (b) stall, washout type | 2 | 2 |
| (c) wall | ||
| (i) washout type | 1½ | 1½ |
| (ii) other types | 2 | 3 |
| Water closet | ||
| (a) with flush tank | 3 | 4 |
| (b) with direct flush valve | 3 | 6 |
| Notes to Table 2.4.9.3.: | |
|
|
|
| (1) | See Appendix A. |
| (2) | No hydraulic load for emergency floor drains. |
Where clothes washers do not drain to a laundry tray, the trap inlet shall be fitted with a vertical standpipe that is not less than 600 mm long measured from the trap weir and terminates above the flood level rim of the clothes washer. (See Appendix A.) 2.4.9.4. Size of Building Drain and Building Sewer
The size of every building drain and building sewer connected to the public sewer system downstream of the main cleanout (see Sentence 2.4.7.1.(6)) shall be not less than 4 inches.
2.4.9.5. Offset in Leaders
No change in the size of a leader with a nominally horizontal offset is required if the offset2.4.10. Hydraulic Loads
(See Appendix A for determination of hydraulic loads and drainage pipe sizes.)2.4.10.1. Total Load on a Pipe
The hydraulic load on a pipe is the total load from2.4.10.2. Hydraulic Loads for Fixtures
The hydraulic load from a fixture that is listed in Table 2.4.9.3. is the number of fixture units set forth in the Table.
Except as provided in Sentence (1), the hydraulic load from a fixture that is not listed in Table 2.4.9.3. is the number of fixture units set forth in Table 2.4.10.2. for the trap of the size that serves the fixture. | Table 2.4.10.2. Permitted Hydraulic Load from a Fixture Based on Size of Trap Forming part of Sentence 2.4.10.2.(2) | |
|
Hydraulic Load, fixture units | |
| 1¼ | 1 |
| 1½ | 2 |
| 2 | 3 |
| 2½ | 4 |
| 3 | 5 |
| 4 | 6 |
2.4.10.3. Hydraulic Loads from Fixtures with a Continuous Flow
Except as provided in Sentence (2), the hydraulic load from a fixture that produces a continuous flow, such as a pump or an air-conditioning fixture, is 31.7 fixture units for each litre per second of flow.
Where a fixture or equipment that produces a continuous or semi-continuous flow drains to a combined sewer or to a storm sewer, the hydraulic load from the fixture is 900 L for each litre per second of flow.
2.4.10.4. Hydraulic Loads from Roofs or Paved Surfaces
Book I (General) of this Code
, multiplied by the sum of
Flow control roof drains may be installed provided
not more than 30 m apart along the perimeter of the building so that
up to 200% of the 15-minute rainfall intensity can be handled, and
the maximum depth of controlled water is limited to 150 mm,
Hydraulic loads in litres per second for flow control roof drains and restricted paved area drains shall be determined according to rain intensity-duration frequency
curves as compiled by Environment Canada using 25-year frequencies.

Where the height of the parapet is more than 150 mm or exceeds the height of the adjacent wall flashing,
2.4.10.5. Conversion of Fixture Units to Litres
Except as provided in Sentence 2.4.10.3.(2), where the hydraulic load is to be expressed in litres, fixture units shall be converted as follows:2.4.10.6. Hydraulic Loads to Soil-or-Waste Pipes
Except as provided in Sentence (2), the hydraulic load that is drained to every soil-or-waste stack shall conform to Table 2.4.10.6.A.
Where the nominally horizontal offset in a soil-or-waste stack is 1.5 m or more, the hydraulic load that
is served by it shall conform to Table 2.4.10.6.B or Table 2.4.10.6.C, whichever is the less restrictive. | Table 2.4.10.6.A Maximum Permitted Hydraulic Load Drained to a Soil-or-Waste Stack Forming part of Sentence 2.4.10.6.(1) | ||
|
Size of Stack, inches |
Maximum Hydraulic Load, fixture units |
Maximum Fixture Units Drained from any 1 Storey |
| 1¼ | 2 | 2 |
| 1½ | 8 | 2 |
| 2 | 24 | 6 |
| 3 | 102 | 18 |
| 4 | 540 | 100 |
| 5 | 1 400 | 250 |
| 6 | 2 900 | 500 |
| 8 | 7 600 | 830 |
| 10 | 15 000 | 2 700 |
| 12 | 26 000 | 4 680 |
| 15 | 50 000 | 9 000 |
| Table 2.4.10.6.B Maximum Permitted Hydraulic Load Drained to a Branch Forming part of Sentence 2.4.10.6.(2) and Article 2.4.10.7. | |
|
Maximum Hydraulic Load, fixture units | |
| 1¼ | 2 |
| 1½ | 3 |
| 2 | 6 |
| 2½ | 12 |
| 3 | 27 |
| 4 | 180 |
| 5 | 390 |
| 6 | 700 |
| 8 | 1 600 |
| 10 | 2 500 |
| 12 | 3 900 |
| Table 2.4.10.6.C Maximum Permitted Hydraulic Load Drained to a Sanitary Building Drain or Sewer Forming part of Sentence 2.4.10.6.(2) and Article 2.4.10.8. | ||||||
|
Size of Drain or Sewer, inches |
Maximum Hydraulic Load, fixture units |
|||||
| Slope | ||||||
| 1 in 400 | 1 in 200 | 1 in 133 | 1 in 100 | 1 in 50 | 1 in 25 | |
| 3 | — | — | — | — | 27 | 36 |
| 4 | — | — | — | 180 | 240 | 300 |
| 5 | — | — | 380 | 390 | 480 | 670 |
| 6 | — | — | 600 | 700 | 840 | 1 300 |
| 8 | — | 1 400 | 1 500 | 1 600 | 2 250 | 3 370 |
| 10 | — | 2 500 | 2 700 | 3 000 | 4 500 | 6 500 |
| 12 | 2 240 | 3 900 | 4 500 | 5 400 | 8 300 | 13 000 |
| 15 | 4 800 | 7 000 | 9 300 | 10 400 | 16 300 | 22 500 |
2.4.10.7. Hydraulic Loads on Branches
2.4.10.8. Hydraulic Loads on Sanitary Building Drains or Sewers
The hydraulic load that is drained to a sanitary building drain or a sanitary building sewer shall conform to Table 2.4.10.6.C. 2.4.10.9. Hydraulic Loads on Storm or Combined Building Drains or Sewers
The hydraulic load that is drained to a storm building drain, a storm building sewer or a combined building sewer shall conform to Table 2.4.10.9.| Table 2.4.10.9. Maximum Permitted Hydraulic Load Drained to a Storm Building Drain or Sewer or a Combined Building Sewer Forming part of Article 2.4.10.9. | |||||||
|
Size of Drain or Sewer, inches |
Maximum Hydraulic Load, L | ||||||
| Slope | |||||||
| 1 in 400 | 1 in 200 | 1 in 133 | 1 in 100 | 1 in 68 | 1 in 50 | 1 in 25 | |
| 3 | — | — | — | — | —![]() | 2 770 | 3 910 |
| 4 | — | — | — | 4 220 | 5 160 | 5 970 | 8 430 |
| 5 | — | — | 6 760 | 7 650 | 9 350 | 10 800 | 15 300 |
| 6 | — | — | 10 700 | 12 400 | 15 200 | 17 600 | 24 900 |
| 8 | — | 18 900 | 23 200 | 26 700 | 32 800 | 37 800 | 53 600 |
| 10 | — | 34 300 | 41 900 | 48 500 | 59 400 | 68 600 | 97 000 |
| 12 | 37 400 | 55 900 | 68 300 | 78 700 | 96 500 | 112 000 | 158 000 |
| 15 | 71 400 | 101 000 | 124 000 | 143 000 | 175 000 | 202 000 | 287 000 |
2.4.10.10. Hydraulic Loads to Roof Gutters
| Table 2.4.10.10. Maximum Permitted Hydraulic Load Drained to a Roof Gutter Forming part of Article 2.4.10.10. | |||||
|
Size of Gutter, inches |
Area of Gutter, cm2 |
Maximum Hydraulic Load, L | |||
| Slope | |||||
| 1 in 200 | 1 in 100 | 1 in 50 | 1 in 25 | ||
| 3 | 22.8 | 406 | 559 | 812 | 1 140 |
| 4 | 40.5 | 838 | 1 190 | 1 700 | 2 410 |
| 5 | 63.3 | 1 470 | 2 080 | 2 950 | 4 170 |
| 6 | 91.2 | 2 260 | 3 200 | 4 520 | 6 530 |
| 7 | 124.1 | 3 250 | 4 600 | 6 500 | 9 190 |
| 8 | 162.1 | 4 700 | 6 600 | 9 400 | 13 200 |
| 10 | 253.4 | 8 480 | 12 000 | 17 000 | 23 600 |
2.4.10.11. Hydraulic Loads on Leaders
| Table 2.4.10.11. Maximum Permitted Hydraulic Load Drained to a Leader Forming part of Article 2.4.10.11. | |||
|
Circular Leader |
Non-Circular Leader | ||
| Maximum Hydraulic Load, L |
Area of Leader, cm2 | Maximum Hydraulic Load, L | |
| 2 | 1 700 | 20.3 | 1 520 |
| 2½ | 3 070 | 31.6 | 2 770 |
| 3 | 5 000 | 45.6 | 4 500 |
| 4 | 10 800 | 81.1 | 9 700 |
| 5 | 19 500 | 126.6 | 17 600 |
| 6 | 31 800 | 182.4 | 28 700 |
| 8 | 68 300 | 324.3 | 61 500 |
2.4.10.12. Hydraulic Loads from Fixtures with a Semi-continuous Flow
The hydraulic load from a fixture or equipment that produces a semi-continuous flow shall conform to Table 2.4.10.12.| Table 2.4.10.12. Maximum Permitted Hydraulic Load from Fixtures with a Semi-continuous Flow Forming part of Sentence 2.4.10.12.(1) | ||
| Flow, L/s |
Hydraulic Load, fixture units | |
| 1½ | 0.00 - 0.090 | 3 |
| 2 | 0.091 - 0.190 | 6 |
| 3 | 0.191 - 0.850 | 27 |
| 4 | 0.851 - 5.700 | 180 |
2.4.10.13. Design of Storm Sewers
Except as provided in Sentences 2.4.10.4.(1) and (2), and Article 2.4.10.9., storm sewers may be designed in accordance with good engineering practice.
