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Heads up: There are no amended sections in this chapter.
Each plumbing fixture or waste inlet shall be separately trapped by a trap integral with the plumbing fixture, or by a waterseal trap placed as near to the fixture or waste inlet as possible.

FIGURE P-501.1


FIGURE P-501.1 Exc. #1


  1. A combination fixture having only one trap, provided that no separate compartment of such fixture is deeper than any other compartment connected to the same trap, and the waste outlets of such compartments are not more than 30 inches apart.
  2. Kitchen sinks with two compartments of different levels and having a continuous waste and one trap. The trap and waste line shall be 1-1/2 inches minimum.

    Figure P-501.1 Exc. #2


    Figure P-501.1 Exc. #3

  3. Kitchen sinks with three compartments, where one or more may be of different levels and having continuous waste and one trap. In accordance with Section P-506.1, the trap and waste line shall be 2 inches minimum.
  4. A set of three single compartment laundry trays which are connected to one trap, provided that the waste outlets are no more than 30 inches apart, and the trap is centrally located.

    Figure P-501.1 Exc. #4

  5. Dishwasher wastes which are discharged through a directional flow fitting located in the sink fixture trap or in the garbage grinder, provided a fixture drain loop is installed on the dishwasher waste to the highest point below the fixture rim and the distance on center between the waste outlets of the sink and the dishwasher does not exceed 6 feet.

    Figure P-501.1 Exc. #5

The use or installation of the following types of traps is prohibited:
  1. Any trap whose seal depends upon the action of movable parts;
  2. Any trap with interior partitions, except when integral with vitrified clay plumbing fixtures;
  3. Double traps, unless a fresh air inlet is connected to the system between the traps;
  4. Crown-vented traps.
Each fixture trap shall have a water seal.
Each fixture trap, except those cast integral or in combination with fixtures in which the trap seal is readily accessible, or except when a portion of the trap is readily removable for cleaning purposes, shall have an accessible brass or nylon resin trap screw of ample size.
All traps shall be set true with respect to their water levels and shall be protected from freezing and evaporation and other loss of seal.
All floor drains, including cellar drains, shall be trapped. Floor drain traps shall be located at such depth below the drain inlet as to be readily accessible for cleaning. A cleanout is not required for a floor drain. A trap primer shall be installed when required by Section P-1204.3.
An approved house trap shall be installed in each sanitary house drain and in each house storm drain located within the property line of the building they serve, and shall be located at the curb line or in the building just inside the foundation wall. There shall be an air inlet for fresh air entering the house drain just inside the water seal of the trap.

Exception: Individual on-site subsurface sewage disposal system. (See Section P-1401.2)
The house trap shall not be less in size than the house drain pipe it traps, and in no case less than 5 inches for sanitary or combination sewers or 6 inches for storm sewers. No flex seal coupling shall be permitted. Fresh air inlets shall be 4 inches for 5-inch and 6-inch drains; 6 inches for 8-inch drains; two 6-inch vents for 10-inch drains with 8-inch standpipe; two 6-inch vents for 12-inch drains with 10-inch standpipe; two 6-inch vents for 15-inch drains with 10-inch standpipe. Where two fresh air inlets are used, connections shall be made by use of a wye on the standpipe. Vents larger than 6 inches shall not terminate at ground level. In lieu of multiple vents, use of "Shuster" type vent or equal, properly sized, shall be permitted.
Air inlets shall lead to the outer air and open at a convenient point, on the footway in the front of the building or at the curb line, and shall have a cover with openings at least three-fourths of the area of the pipe. In no case shall an air inlet open within 10 feet of any door, window, or fresh air intake for a heater or ventilation system.
They shall be so arranged as to prevent the admission of sticks or other articles that would tend to obstruct the main trap. They shall be at least 1/4 inch in thickness and fastened with brass screws or bolts in order that the top can be removed if necessary, and the body shall be caulked fast to the upright pipe by a lead joint. Only approved air inlets shall be used.
Brass traps for lavatories and sinks shall have a minimum wall thickness of No. 17 Brown & Sharpe gauge, and the number of the gauge shall be stamped into the metal for inspection. Schedule 40 ABS or PVC plastic shall be allowed in accordance with Section P-902.5.
Traps of 17-gauge are not permitted to be used as bath traps. The minimum size trap shall be 1-1/2 inches inside nominal diameter and shall have a water seal of not less than 2 inches and not more than 4 inches.
Traps for bath tubs shall be made of cast brass, cast iron, DWV copper, galvanized durham piping, ABS, or PVC. ABS and PVC plastic traps shall conform to the size of the trap and "ABS Tubular F409," "PVC Tubular F409" or "P Tubular F409" shall be installed in accordance with Section P-902.5.
A minimum 14-inch wide and 28-inch high panel shall be provided to afford access to the bath trap. It shall be located on the wall behind the end of the bath tub where the drain outlet is located. The access panel shall be a minimum 12" x 18" when located in the ceiling below.

Exceptions: Access panels shall not be required for the following:
  1. Buildings of Use Group R-1.
  2. Buildings of Use Group R-2 containing more than 8 stories of dwelling units.
  3. Where trap joints are soldered, solvent cemented or screwed so as to form a solid connection.
Access panels which are installed within fireresistance rated assemblies shall be labeled doors of the required fireresistance rating. Installation in stairway enclosures is prohibited.
Except for fixtures with integral traps, the size of a trap for a given fixture shall not be smaller than specified in Table P-506.

Fixture Minimum Size of Trap & Fixture Drain
Bathtub (with or without shower) 1 1/2
Bidet 1 1/4
Combinations Fixture (not over 2 compartments on the same level) 1 1/2
Dishwasher, Commercial 2
Domestic Washing Machine 1 1/2
Drinking Fountain or Electric Water Cooler 1 1/4
Floor Drain 3
Fountain Cuspidor (Dental chair) 1 1/4
Laundry Tray (1 or 2 compartments) 1 1/2
Laundry Tray (3 compartments) 2
Lavatory 1 1/4
Shower Stall (1 shower head and body sprays) 1 1/2
Shower Stall (2 or 3 shower heads) 2
Shower Stall Receptor receiving discharge from:
4 to 5 shower heads
over 5 shower heads
Sink, Dishwasher, Residence 1 1/2
Sink, Kitchen, Residence, single or double compartment 1 1/2
Sink, Kitchen, Residence, 3 compartments 2
Sink, Pot or Scullery, Hotel or Public 2
Sink, Service or mop receptor 3
Sink, Soda Fountain or Bar 1 1/4
Urinal, Stall 2
Urinal, Trough 1 1/2
Urinal, Wall 1 1/2
Wash Fountain 2
Wash Sink, 6 ft. 1 1/2
Wash Sink, more than 6 ft. 2
No trap or fixture drain shall be less than 1-1/4 inches, except as provided for in Section P904.5. The fixture drains for water closets, trap standard service sinks and pedestal urinals with integral traps shall not be less than 3 inches.
Each fixture trap shall have a water seal of not less than 2 inches and not more than 4 inches. When a trap is required on a rainwater conductor, the seal shall not be less than 4 inches.
A cleanout shall be provided at or near the foot of each vertical waste or soil stack. A test fitting with an iron pipe size screw opening as prescribed in Section P-1503 shall be accepted to serve as a cleanout.
Any bolted or threaded floor or wall connection of a fixture trap shall be accepted as a cleanout.
Cleanouts in horizontal drainage lines of 4-inch nominal diameter or less shall not be more than 50 feet apart and not more than 100 feet apart for larger pipe sizes. Cleanout as required in Section P-507.1 shall be accepted to satisfy this requirement.
The bodies of cleanout ferrules shall conform in thickness to that required for pipe and fittings of the same metal or of nylon resin, shall extend not less than 1/8 inch and shall be provided with a raised nut or recessed socket for removal.
Both ferrule and plug shall have American National Tapered Pipe Threads and are permitted for repairing a cleanout, where necessary.
Cleanouts shall be of the same nominal size as the pipes into which they are installed, up to 4 inches and not less than 4 inches for larger pipes.
All required cleanouts shall be located so as to be readily accessible.
The openings of all underground or below-floor cleanouts in a building shall be flush with or above the floor and shall be accessible in manholes or through access doors.
Exterior underground cleanouts shall be extended to the surface or otherwise made accessible.
Cleanouts concealed in or by walls or ceilings shall either be extended to the exposed surface of such walls or ceilings or shall be accessible through access doors.
Cleanouts on 4-inch or larger pipes shall be so installed that there is a clearance of not less than 18 inches for rodding. Cleanouts smaller than 4 inches shall have not less than 6 inches clearance.
Where waste discharged into a drainage system contains or is likely to contain substances which hinder sewage disposal, such as non-soluble, flammable, or hazardous substances, and where required by the Industrial Wastes Division of the Water Department, an approved interceptor shall be installed which effectively prevents such substances from entering the public sewer.
All floor drains in garages shall be an approved type.
All interceptors shall be so designed that they will not become air-bound or permit siphonage. They shall be located so as to be readily accessible for cleaning and inspection.
The flow rate through an interceptor shall not exceed its rated capacity, and the interceptor shall operate at a minimum overall efficiency of 90% while draining the fixture in 2 minutes.
Grease interceptors shall have a flow-control fitting capable of external cleaning.
No interceptor shall be considered a trap, unless the outlet is at least 1-1/2 inches above the inlet.

Exception: Grease interceptors (see Section P-510.4).
All fixture outlets shall be individually trapped, all traps shall be properly vented, and a fresh air inlet or vent shall be installed on the house side of the interceptor and shall have a vacuum breaker or vent. This is not applicable to a single fixture directly entering the grease trap.

Figure P-508.7

Figure P-508.7a
Note: Single Fixtures Requires No Vent Within Legal Distance.
When required by the Industrial Waste Division of the Water Department, an approved oil interceptor shall be installed in the drainage systems of buildings, structures, parts of buildings, and premises of the following uses or occupancies:
  1. Commercial garages, auto repair shops, service stations, trucking docks, and any other place where gasoline or other flammable liquid with flash-point less than 90° F is dispensed or regularly used in connection with the work performed or processes employed;
  2. Dry cleaners or dyers using solvents;
  3. Paint, lacquer, or varnish factories;
  4. Printing in manufacturing plants.
Oil interceptors shall be constructed so as to be oil-tight and shall have easily removable watertight and gas-tight covers.
Every oil interceptor shall have a separate vent on the terminal end of the inlet piping and a fresh air inlet on the sewer side of the interceptor tank to relieve vapor. The size of the fresh air inlet shall not be less than 2 inches in size. The fresh air inlet shall be connected to the interceptor tank and extended to the outer air in accordance with Section P-503 or other location approved by the Department.
Construction of oil interceptors shall be one of the following:
  1. Reinforced concrete with the base, baffle wall and exterior walls not less than 6-inches thick; or
  2. 8-inch sewer brick parged to a smooth finish on the interior walls; or
  3. 8-inch 75% solid concrete block parged to a smooth finish on the interior walls; or
  4. Other materials as approved by the Department.
Adequate access to each compartment of the intercepting tank shall be provided by a minimum 18- inch manhole and removable cover. Manhole covers shall be cast iron or pre-cast reinforced concrete set into a retaining ring, and each cover shall weigh not less than 63 pounds. Manholes shall be brought up to grade and be water-tight and gas-tight.
An approved grease interceptor shall be installed wherever grease as a product or byproduct is introduced into a drainage system in sufficient quantity to cause line stoppage or hinder sewage disposal. The grease interceptor shall be installed in connection with the following uses or occupancies when required by the Industrial Waste Division of the Water Department:
  1. All wastes in meat preparation areas, pot sinks, dishwashing machines and can washers for public eating places, institutions, and schools;
  2. Slaughterhouses and meat-packing or meat-processing plants;
  3. Rendering plants;
  4. Soap factories.
When a grease interceptor is installed, it shall be located as near as possible to the fixture or fixtures served and shall be readily accessible for cleaning.
Grease interceptors shall be constructed of impervious materials capable of withstanding shock from hot and cold water, shall be water-tight, and shall be equipped with easily removable, water-tight and gastight covers, and cleaning devices.
The trap seal on grease interceptors shall not be less than 4 inches and shall conform to Section P501.2.
An approved hair or lint interceptor shall be installed wherever hair or lint is introduced into the drainage system in sufficient quantity to cause line stoppage and shall be installed in connection with the following uses or occupancies when required by the Industrial Waste Division of the Water Department.
  1. Commercial, institutional, hotel, club or other laundries equipped with commercial-type laundry equipment;
  2. Beauty parlors and beauty operator training schools having 6 or more lavatories draining to a common house drain;
  3. Dry cleaning establishments;
  4. Hide or fur processing plants;
  5. Establishments having laundry equipment on the premises for public use.
The wastes from stables, barns, stable yards, barnyards, manure pits, and subsurface drainage pipes shall pass through an intercepting catch basin before entering the house drain, lateral or public sewer.
Sand and similar interceptors shall be designed and located so as to be readily accessible for cleaning and shall have a trap seal of not less than 6 inches.
Floor drains shall be equipped with removable basket strainers where necessary to prevent solids which might cause line stoppage from entering the drainage lines.
Installation of domestic garbage grinders shall be permitted when the drainage system is connected to a City sewer or to sewers which are so arranged as to discharge into a sewage treatment plant. Connection of commercial garbage grinders to a combination sewer leading to a sewage treatment plant is permitted. When such public sewers are unavailable, domestic and commercial garbage grinder drainage shall be in accordance with Chapter 14.
The efflux from a domestic grinder shall be carried off through a trap and waste pipe with a minimum inside diameter of 1-1/2 inches. The efflux from a commercial grinder shall be carried off through a trap and waste pipe with a minimum inside diameter of 2 inches. The waste pipe from a commercial garbage grinder shall not exceed 12 feet in length from a vented soil or waste connection. Garbage grinders shall not be installed on a waste line where an interceptor is required by Section P-510.1.
For both domestic and commercial garbage grinders, the model number and manufacturer's name shall be permanently identified by a nameplate or by an indented marking on each grinder installed.
The testing and approval of all garbage disposal units shall be authorized by and under the jurisdiction of the Water Department.
Sewer gate valves shall be one of the following types:
  1. Manually-operated rising stem type;
  2. Swinging disk back pressure type; or
  3. Any other type of back pressure valve approved by the Department.
Sewer gate valves shall be constructed of corrosion-resistant material.
When fully open, sewer gate valves shall have a free-opening cross section not less than the pipe in which they are installed.

Figure P-514.3

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