Section 7.4 — Drainage Systems

(1) This Section applies to sanitary drainage systems and storm 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))

(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.

(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.

(1) Sanitary units, bathtubs and shower baths shall not be installed adjacent to wall and floor surfaces that are pervious to water.

(1) Indirect connections or any trap that may overflow shall not be located in a crawl space or any other unfrequented area.

(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.

(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.

(1) A maceration toilet system shall only be installed (a) where no connection to a gravity sanitary drainage system is available, and (b) in accordance with the manufacturer’s instructions.

(1) If a floor drain is provided in an elevator pit, it shall be installed in accordance with Section 2.2. of ASME A17.1 / CSA B44, “Safety Code for Elevators and Escalators.”

(1) Where a fixture or equipment discharges sewage or waste that may damage or impair the sanitary drainage system or the functioning of a sanitary sewage works or sanitary sewage system, provision shall be made for treatment of the sewage or waste before it is discharged to the sanitary drainage system.

(1) Where a fixture discharges sewage or clear-water waste that has been heated, the drainage system shall be suitable for the temperature of the sewage or clear-water waste being discharged. (See Note A-7.4.4.2.(1))

(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:  N  V    Q =   0.75    1  + PD DDT   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.

(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-7.4.4.4.(1)) (2) Neutralizing or dilution tanks shall have a method for neutralizing the liquid.

(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.

(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.

(1) 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. (2) Except as permitted in Sentence (3), no foundation drain or subsoil drainage pipe shall connect to a sanitary drainage system. (3) Where a storm drainage system is not available or soil conditions prevent drainage to a culvert or dry well, a foundation drain or subsoil drainage pipe may connect to a sanitary drainage system.

(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.

(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 ⅜ in. inside diameter.

(1) No vertical sanitary drainage pipe shall conduct both sanitary sewage and storm sewage. (2) Reserved. (3) 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.

(1) A sanitary drainage pipe shall not be located directly above, (a) non-pressure potable water storage tanks, (b) manholes in pressure potable water storage tanks, or (c) food-handling or food-processing equipment.

(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.

(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.

(1) A building sewer intended to serve a mobile home shall be (a) not less than NPS 4, (b) terminated above ground, (c) provided with (i) a tamperproof terminal connection that is capable of being repeatedly connected, disconnected and sealed, (ii) a protective concrete pad, and (iii) a means to protect it from frost heave, and (d) designed and constructed in accordance with good engineering practice.

(1) Where a building drain enters a building above the elevation of the bottom of the wall of a building, the building drain may be deemed to terminate at the first point that the drainage pipe changes direction from the horizontal to the vertical.

(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.

(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. Table 7.4.7.2. Permitted Size and Spacing of Cleanouts Forming Part of Sentence 7.4.7.2.(1) Nominal Pipe Size of Minimum Nominal Pipe Size of Maximum Spacing, m Drainage Pipe, NPS Cleanout, NPS One-Way Rodding 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 (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.

(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.

(1) Cleanouts and access covers shall be located so that their openings are readily accessible for drain cleaning purposes. (2) A cleanout shall not be (a) located in a floor assembly in a manner that may constitute a hazard, and (b) used as a floor drain. (3) Reserved. (4) Each change of direction of the piping between a cleanout fitting and the drainage piping or vent piping that it serves shall be accomplished by using 45 bends. (4.1) A cleanout shall be provided to serve vertical drainage piping from a wall hung urinal and shall extend above the flood level rim of the fixture. (5) Cleanouts serving fixture drains in healthcare facilities, mortuaries, laboratories and similar occupancies, where contamination by hazardous waste is likely, shall be located a minimum of 150 mm above the flood level rim of the fixture.

(1) Except as provided in Sentences (2) and (3) and Articles 7.4.10.8. and 7.4.10.9., drainage pipes that are NPS 3 or less shall have a downward slope in the direction of flow of at least 1 in 50. (See Note A-7.4.8.1.(1)) (2) Sentence (1) does not apply to a force main. (3) Where it is not possible to comply with Sentence (1), a lesser slope may be used if it will produce a gravity flow of not less than 0.6 m per second.

(1) Except for fixture outlet pipes installed in conformance with Sentence 7.4.5.1.(3), the developed length of fixture outlet pipes shall not exceed 1 200 mm.

(1) Except as permitted in Sentence (3), no drainage pipe that is of minimum size required by this Part for the purpose for which it is installed shall be so connected as to drain to other drainage pipe of lesser size. (2) Where a building drain connects to a stack through a wall or floor, the drain shall retain its full size through the wall or floor. (3) A sanitary drainage pipe may be connected to a pre-engineered waste water heat recovery system that incorporates piping of a lesser size than required by Sentence (1) provided that it does not convey sewage (a) from a sanitary unit, or (b) that contains solids.

(1) Drainage pipes that serve a water closet shall be not less than NPS 3. (2) Branch and building drains downstream of the third water-closet fixture drain connection shall be not less than NPS 4. (3) Stacks that serve more than 6 water closets shall be not less than NPS 4. (4) Discharge pipes serving a macerating toilet system shall be not less than NPS ¾. (5) No vertical leg of the drainage pipe from a water closet or other fixture that has an integral siphonic flushing action shall exceed 1 000 mm.

(1) Except as provided in Sentence (2), the nominal pipe size of fixture outlet pipes shall conform to Table 7.4.9.3. (2) The part of the fixture outlet pipe that is common to 3 compartments of a sink shall be one NPS larger than the largest fixture outlet pipe of the compartments that it serves. (See Note A-7.4.9.3.(2)) (3) Where clothes washers do not drain to a laundry tray, the trap inlet shall be not less than NPS 2 and 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 Note A-7.4.9.3.) (4) In an individual dwelling unit, where multiple shower heads are served by one shower receptacle, the fixture outlet pipe shall be not less than NPS 2. Table 7.4.9.3. Minimum Permitted Size of Fixture Outlet Pipe and Hydraulic Loads for Fixtures (1) Forming Part of Sentences 7.4.9.3.(1) and 7.4.10.2.(1) Minimum Nominal Pipe Size of Fixture Hydraulic Load, fixture units Fixture Outlet Pipe, NPS Autopsy table 1½ 2 Bathroom group (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 Chinese range 1½ 3 Clothes washer (a) domestic(1) n/a 1½ with NPS 2 trap (b) commercial n/a 2 with NPS 2 trap Cup Sinks 1¼ ½ Dental unit or cuspidor 1¼ 1 Dishwasher 1 (no load when connected to (a) domestic type 1½ garbage grinder or domestic sink) (b) commercial type 2 3 Drinking fountain 1¼ ½ Fish tank or tray 1½ 1½ 2 with NPS 2 trap Floor drain(2) 2 3 with NPS 3 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) compartments 1½ 2 Lavatory (a) barber or beauty parlor 1½ 1½ (b) dental 1¼ 1 1 with NPS 1¼ trap (c) domestic type single, or 2 single with common trap 1¼ 1½ with NPS 1½ trap (d) multiple or industrial type 1½ According to Table 7.4.10.2. Macerating Toilet System ¾ 4 Potato Peeler 2 3 Table 7.4.9.3. (Cont’d) Minimum Permitted Size of Fixture Outlet Pipe and Hydraulic Loads for Fixtures (1) Forming Part of Sentences 7.4.9.3.(1) and 7.4.10.2.(1) Minimum Nominal Pipe Size of Fixture Hydraulic Load, fixture units Fixture Outlet Pipe, NPS Shower drain Total volume of discharge from all shower heads and body sprays: (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 1½ 1½ grinders, single, double or 2 single with a common trap 1½ with NPS 1½ trap (b) other sinks 1½ 2 with NPS 2 trap 3 with NPS 3 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 7.4.9.3.: (1) See Note A-Table 7.4.9.3. (2) No hydraulic load for emergency floor drains.

(1) Building drains and building sewers connected to the public sewer system downstream of the main cleanout (see Sentence 7.4.7.1.(6)) shall be not less than NPS 4. (2) Storm building drains and storm building sewers shall be not less than NPS 4.

(1) No change in the nominal pipe size of a leader with a nominally horizontal offset is required if the offset (a) is located immediately under the roof, (b) is not more than 6 m long, and (c) has a slope of not less than 1 in 50. (2) If the horizontal offset is more than 6 m long, the leader shall conform to Table 7.4.10.9.

(1) The hydraulic load on a pipe is the total load from (a) every fixture that is connected to the system upstream of the pipe, (b) every fixture for which provision is made for future connection upstream of the pipe, and (c) all roofs and paved surfaces that drain into the system upstream of the pipe.

(1) The hydraulic load from a fixture that is listed in Table 7.4.9.3. is the number of fixture units set forth in the Table. (2) Except as provided in Sentence (1), the hydraulic load from a fixture that is not listed in Table 7.4.9.3. is the number of fixture units set forth in Table 7.4.10.2. for the nominal pipe size of the trap that serves the fixture. Table 7.4.10.2. Permitted Hydraulic Load from a Fixture Based on Size of Trap Forming Part of Sentence 7.4.10.2.(2) Nominal Pipe Size of Trap, NPS Hydraulic Load, fixture units 1¼ 1 1½ 2 2 3 2½ 4 3 5 4 6

(1) 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. (2) 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.

(1) Except as provided in Sentence (2), the hydraulic load in litres from a roof or paved surface is the maximum 15 min rainfall determined in conformance with MMAH Supplementary Standard SB-1, “Climatic and Seismic Data,” multiplied by the sum of (a) the area in square metres of the horizontal projection of the surface drained, and (b) one-half the area in square metres of the largest adjoining vertical surface. (See Note A-7.4.10.4.(1)) (2) Flow control roof drains may be installed, provided (a) the maximum drain down time does not exceed 24 h, (b) the roof structure is designed to carry the load of the stored water, (c) one or more scuppers are installed not more than 30 m apart along the perimeter of the building so that (i) up to 200% of the 15-minute rainfall intensity can be handled, and (ii) the maximum depth of controlled water is limited to 150 mm, (d) they are located not more than 15 m from the edge of the roof and not more than 30 m from adjacent drains, and (e) there is at least one drain for each 900 m2. (3) Reserved. (4) Where the height of the parapet is more than 150 mm or exceeds the height of the adjacent wall flashing, (a) emergency roof overflows or scuppers described in Clause (2)(c) shall be provided, and (b) there shall be a minimum of 2 roof drains.

(1) Except as provided in Sentence 7.4.10.3.(2), where the hydraulic load is to be expressed in litres, fixture units shall be converted as follows: (a) when the number of fixture units is 260 or fewer, the load is 2 360 L, and (b) when the number of fixture units exceeds 260, the load is 9.1 L for each fixture unit. (2) Where the hydraulic load is to be expressed in gal/min, fixture units shall be converted in accordance with Table 7.4.10.5. Table 7.4.10.5.(1) Maximum Probable Drainage Rate, gal/min Forming Part of Sentence 7.4.10.5.(2) Fixture Units Fixture Units Fixture Units Fixture Units in Service Col. 1 Col. 1 × 10 Col. 1 × 100 100 53 174 900 90 51 164 835 80 49 153 750 70 47 140 680 60 44 128 600 50 41 115 520 40 38 102 435 30 33 88 350 20 27 72 262 10 21 53 174 Notes to Table 7.4.10.5.: (1) See Note A-Table 7.4.10.5.

(1) Except as provided in Sentence (2), the hydraulic load that is drained to every stack shall conform to Table 7.4.10.6.-A. (2) Where the nominally horizontal offset in a stack is 1.5 m or more, the hydraulic load that is served by it shall conform to Table 7.4.10.6.-B or Table 7.4.10.6.-C, whichever is the less restrictive. (3) Vertical sanitary drainage pipe shall be designed to carry no more than 29% of its full capacity. Table 7.4.10.6.-A Maximum Permitted Hydraulic Load Drained to a Stack Forming Part of Sentences 7.4.10.6.(1) and 7.5.7.3.(2) and Table 7.5.8.4. Maximum Fixture Units Drained from Nominal Pipe Size of Stack, NPS Maximum Hydraulic Load, fixture units 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 7.4.10.6.-B Maximum Permitted Hydraulic Load Drained to a Branch Forming Part of Sentences 7.4.10.6.(2), 7.4.10.7.(1) and 7.5.7.3.(2) Nominal Pipe Size of Branch, NPS Maximum Hydraulic Load, fixture units 1¼ 2 1½ 3 2 6 3 27 4 180 5 390 6 700 8 1 600 10 2 500 12 3 900 Table 7.4.10.6.-C(1) Maximum Permitted Hydraulic Load Drained to a Sanitary Building Drain or Sewer Forming Part of Sentence 7.4.10.6.(2) and Article 7.4.10.8. Nominal Pipe Maximum Hydraulic Load, fixture units Size of Drain or Slope(2) Sewer, NPS 1 in 400 1 in 200 1 in 133 1 in 100 1 in 50 1 in 25 3 n/a n/a n/a n/a 27 36 4 n/a n/a n/a 180 240 300 5 n/a n/a 380 390 480 670 6 n/a n/a 600 700 840 1 300 8 n/a 1 400 1 500 1 600 2 250 3 370 10 n/a 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 Notes to Table 7.4.10.6.-C: (1) See Note A-Table 7.4.10.6.-C. (2) Slope is the ratio of rise to run, in whatever measurement units are chosen.

(1) The hydraulic load that is drained to a branch shall conform to Table 7.4.10.6.-B.

(1) Except as permitted by Article 7.4.10.7., the hydraulic load that is drained to a sanitary building drain or a sanitary building sewer shall conform to Table 7.4.10.6.-C. (2) Horizontal sanitary drainage pipe shall be designed to carry no more than 65% of its full capacity.

(1) The hydraulic load that is drained to a storm building drain, a storm building sewer or a combined building sewer shall conform to Table 7.4.10.9. Table 7.4.10.9. Maximum Permitted Hydraulic Load Drained to a Storm Building Drain or Sewer, or a Combined Building Sewer Forming Part of Sentence 7.4.9.5.(2) and Article 7.4.10.9. Maximum Hydraulic Load, L Nominal Pipe Size of Drain Slope(1) or Sewer, NPS 1 in 400 1 in 200 1 in 133 1 in 100 1 in 68 1 in 50 1 in 25 3 n/a n/a n/a n/a n/a 2 770 3 910 4 n/a n/a n/a 4 220 5 160 5 970 8 430 5 n/a n/a 6 760 7 650 9 350 10 800 15 300 6 n/a n/a 10 700 12 400 15 200 17 600 24 900 8 n/a 18 900 23 200 26 700 32 800 37 800 53 600 10 n/a 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 Notes to Table 7.4.10.9.: (1) Slope is the ratio of rise to run, in whatever measurement units are chosen.

(1) The hydraulic load that is drained to a roof gutter shall conform to Table 7.4.10.10. Table 7.4.10.10. Maximum Permitted Hydraulic Load Drained to a Roof Gutter Forming Part of Article 7.4.10.10. Maximum Hydraulic Load, L Nominal Pipe Size of Gutter, Area of Gutter,cm3 Slope NPS 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

(1) The hydraulic load that is drained to a leader shall conform to Table 7.4.10.11. Table 7.4.10.11. Maximum Permitted Hydraulic Load Drained to a Leader Forming Part of Sentence 7.4.10.11.(1) Circular Leader Non-Circular Leader Nominal Pipe Size of Leader, Maximum Hydraulic Maximum Hydraulic Load, L Area of Leader, cm2 NPS 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

(1) The hydraulic load from a fixture or equipment that produces a semi-continuous flow shall conform to Table 7.4.10.12. Table 7.4.10.12. Maximum Permitted Hydraulic Load from Fixtures with a Semi-continuous Flow Forming Part of Sentence 7.4.10.12.(1) Nominal Pipe Size of Trap, NPS Flow, L/s Hydraulic Load, fixture units 1½ 0.000 - 0.090 3 2 0.091 - 0.190 6 3 0.191 - 0.850 27 4 0.851 - 5.700 180