THE SANITARY PLUMBING AND DRAINAGE SYSTEM

REGULATIONS, 1976

CODE OF PRACTICE

ON

SANITARY PLUMBING AND DRAINAGE SYSTEM

INTRODUCTION

The Code of Practice on Sanitary Plumbing and Drainage System, issued under
regulation 3 of The Sanitary Plumbing and Drainage System Regulations, 1976, shall be
complied with by professional engineers, registered architects and registered plumbers for the
design, installation and execution of all sanitary plumbing and drainage systems.

The requirements under this Code are supplemental to The Sanitary Plumbing and
Drainage System Regulations, 1976. They do not exhaustively cover all aspects of the design,
installation, fixing and testing of Sanitary plumbing and design, layout, construction and testing
of the drainage system but only set out the minimum requirements.

This edition incorporates changes on the design and workmanship based on

improved technology in plumbing.

This Code of Practice may be amended and revised from time to time.

Sewerage Department
Ministry of the Environment
Singapore

iv
 CODE OF PRACTICE

ON

SANITARY PLUMBING AND DRAINAGE SYSTEM

PART I : SANITARY DRAINAGE SYSTEM

1. Design and Layout of Drainage System (1)

1.1 The design and layout of the drainage system shall be as simple and direct as
practicable for the proper conveyance of sewerage within the premises for
discharge to the sewerage system.

2. Branch Drain-Line (1) & (2)

2.1 Every branch drain-line shall have a minimum diameter of 100mm.

2.2 Every branch drain-line shall be connected obliquely in the same direction of flow
as the main drain-line within the inspection chamber by means of curved channel
bedded in cement mortar and finished with a benching sloping 1 in 6 to 1 in 10
upwards to meet the wall of the inspection chamber.

2.3 Every branch drain-line shall be laid in straight run with a constant gradient and
shall be water-tight.

2.4 Every branch drain-line shall have flexible pipe joints.

2.5 Every branch drain-line shall be laid using the same material throughout its entire
length.

2.6 The invert of the branch drain-line entering the inspection chamber shall be
connected above the horizontal diameter of the main channel.

2.7 The gradient of branch drain-lines shall be as follows except otherwise required:-

Diameter of branch drain-line Allowable gradient

100mm 1 in 20 to 1 in 60
150mm 1 in 30 to 1 in 80

Note: Numerals in parenthesis refer to corresponding Appendices in part VI

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3. Main Drain-line (1)

3.1 Every main drain-line shall have a minimum diameter of 150mm.

3.2 The maximum distance of any main drain-line between inspection chambers shall not
exceed 30 metres.

3.3 Every main drain-line shall be laid in a straight run with constant gradient between
inspection chambers and shall be water-tight.

3.4 An inspection chamber shall be provided for every change in direction and every
change in gradient of the main drain-line.
3.5 Where there is any significant difference in invert levels between inspection
chambers a backdrop or tumbling bay connection shall be made between the said
inspection chambers. An indrop connection shall only be used with the prior
approval of the Director.
3.6 Every main drain-line shall have flexible pipe joints.

3.7 Every main drain-line between inspection chambers shall be laid using the same
material throughout its entire length.
3.8 The gradient of main drain-lines shall be as follows except otherwise required:-

Gradient immediately
Diameter of main Allowable gradient
upstream of Backdrop /
drain-line in all other cases
Tumbling Bay
150mm 1 in 60 to 1 in 80 1 in 30 to 1 in 80
225mm 1 in 90 to 1 in 120 1 in 40 to 1 in 120

3.9 No main drain-line shall be sited within service road or backlane.

4. Inlet to Drain-line

4.1 Every inlet to the drain-line shall be properly trapped and capable of maintaining
a water seal of not less than 50mm.
4.2 Proper means of access shall be provided for the purpose of maintenance.
4.3 Every gully trap and inspection chamber shall be located outside the building
where practicable.
4.4 Every gully trap shall be embedded in concrete to a thickness of at least 100mm
all round.

4.5 Every gully trap shall be fixed as near the floor level as practicable and the
distance from the floor level to the bottom of the trap shall not exceed 600mm.

4.6 Every grating to a gully trap shall be fixed at least 15mm above a paved floor to
prevent ingress of rain-water to sewer, unless the gully trap is intended to receive
sullage water, in which case it shall be fixed at least 5mm below the paved floor.
In either case the floor surrounding the grating shall be sloped.
 Page 2
4.7 Every grating to gully trap shall be fixed at least 20mm above an unpaved ground
to prevent ingress of rain-water to sewer and the ground surrounding the grating
shall be sloped.
4.8 Every gully trap shall be extended with a riser between the grating and the socket
of the gully trap. Every waste discharge pipe shall be connected to a gully trap at
a riser below the grating and above the water seal of the trap.
5 Excavation

5.1 Every trench excavation shall be properly timbered to support the walls thereof
from collapsing.
5.2 Where the trench excavation is contiguous to a public thoroughfare or where it
would constitute a danger or hazard to the safety of the public or to any adjoining
property, necessary precautions shall be taken against accidents occurring.
5.3 Adequate appropriate warning signs shall be displayed conspicuously.
5.4 Adequate flashing warning lights shall be displayed at night.

6 Bedding, Haunching and Backfilling to Branch and Main Drain-line (3)

6.1 On firm ground, every drain-line of uPVC, cast iron or ductile iron pipes shall be
on granular bedding provided the cover depth is between 0.6 metre and 2.0
metres.

6.2 On firm ground, every drain-line of uPVC, vitrified clay or reinforced concrete
pipes and of cover depth less than 0.6 metre or more than 2.0 metres shall be
encased with concrete of minimum thickness 100mm.

6.3 On firm ground, every drain-line of vitrified clay or reinforced concrete pipes and
of cover depth between 0.6 metre and 2.0 metres shall be bedded on concrete at
least 100mm thick and properly haunched in concrete to at least 100mm on either
side of the pipe.

6.4 On firm ground, every drain-line of cast iron or ductile iron pipes and of cover
depth less than 0.6 metre or more than 2.0 metres shall be bedded on concrete at
least 100mm thick and properly haunched in concrete to at least 100mm on either
side of the pipe.

6.5 On soft or yielding ground, every drain-line shall be provided with the same
bedding as for firm ground except that the bedding shall be founded on ‘bakau
piles’.
6.6 Granular material for bedding of flexible jointed pipes shall be of such size
ranging from 3mm to 12mm or of a free running coarse sand.

6.7 Selected fill material, free from lumps exceeding 75mm in size and from stones,
shall be placed over the pipes and compacted in layers not exceeding 150mm in
depth to a height of 300mm above the top of the pipes. The remainder of the
trench shall then be backfilled to the surrounding level with ordinary fill material.
 Page 3
6.8 Break-joint for concrete bedding and haunching shall be provided for along every
drain-line at intervals not exceeding 6 metres.

7 Drain-line under Building (3)

7.1 No drain-line shall pass under any building except where an alternative mode of
construction in impracticable.

7.2 Where a drain-line passes under a building, it shall be laid in a straight run for the
whole distance in heavyduty cast iron pipes or ductile iron pipes.

7.3 The pipes shall be bedded on concrete at least 100mm thick and properly
haunched in concrete to at least 100mm on either side of the pipe.

8 Drain-line Under Drive-way and Car-Park (3)

8.1 Every drain-line under a drive-way or car-park shall be laid in heavy duty cast
iron pipes or ductile iron pipes.

8.2 The pipes shall be bedded on concrete at least 100mm thick and properly
haunched in concrete at least 100mm on either side of the pipe.

8.3 Where the depth from the top of the drain-line to the ground level exceeds 1.4m,
other pipes except uPVC pipes may be used. They shall be completely embedded
in concrete to a thickness of at least 100mm all round.

9 Inspection Chamber and Ventilation (4)

9.1 The first inspection chamber of the drainage system shall have a minimum depth
of 750mm from surface level to invert level where practicable.

9.2 The first inspection chamber shall be provided with a ventilating stack of not less
than 100mm in diameter. The ventilating stack shall be an untrapped opening in
the inspection chamber and no bend or angle, except where unavoidable, shall be
formed in any such stack.

9.3 A discharge stack at the first inspection chamber shall constitute a sufficient
opening for such ventilation.

9.4 On firm ground, the inspection chamber shall be constructed on a base of concrete
at least 150mm thick and such base shall extend at least 150mm beyond the
external walls of the inspection chamber.

9.5 On soft or yielding ground, the inspection chamber shall be constructed on

‘bakau’piles and a base of reinforced concrete.
 Page 4
9.6 Every inspection chamber shall have minimum internal dimensions of 900mm in
length and 700mm in width. The length and width shall be increased accordingly
depending on the number of branch drain-lines connected or to be connected to
the inspection chamber and the depth of such inspection chamber.

9.7 The internal dimensions of every inspection chamber shall not exceed 1350mm in
length and 1350mm in width. Where the dimensions exceed 1350mm, an
additional inspection chamber shall be provided.

9.8 Brickwork for the inspection chamber shall be laid in English Bond in level
courses and set in cement mortar. The internal and external walls shall be
plastered with cement mortar.

9.9 The inspection chamber shall be roofed with a reinforced concrete slab of not less
than 150mm thick in all areas and provided with an opening which shall be fitted
with an air-tight frame and cover. Heavy duty cast iron frame and cover shall be
used in every drive-way and car-park.

9.10 Where the inspection chamber is more than 2.5 metres deep but not exceeding 6.0
metres, it shall be constructed in precast concrete sections of 1050mm diameter
with 150mm thick concrete surround and in accordance with the Sewerage
Department’s Standard Drawing for minor sewer.

9.11 Where the inspection chamber exceeds 6.0 metres deep, details of such chamber
shall be submitted by a Professional Engineer for approval prior to
commencement of work.

9.12 Every branch/main channel shall be of half-round vitrified clay pipe.

9.13 The depth of the channel shall not be less than the diameter of the drain-line.

9.14 No inspection chamber shall be sited within the kitchens of restaurants and eating
houses.

9.15 The last inspection chamber shall be located within 2.5 metres of the lot
boundary.

9.16 No inspection chamber shall be sited within 2.5 metres of the top or bottom of an
embarkment.
10 Testing

10.1 Every drain-line laid shall be water-tight and subjected to a water test under a
static head of not less than 1 metre of water.

10.2 The said water test shall be applied after laying and before placing concrete for
haunching or encasing. Any leakage in the drain-line shall be rectified.
 10.3 Every inspection chamber shall be water-tight and subjected to a water test.

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(5)
11 Wash Area

11.1 Every wash area shall have a minimum area of 2.0 square metres (length 1.7m
and width 1.2m) and a maximum area of 2.7 square metres (length 1.8m and
width 1.5m).

11.2 Every wash area shall be constructed in concrete not less than 75mm thick with a
curbing of 75mm by 75mm all round and rendered smooth with cement mortar or
other impervious material.

11.3 Any wash area may be recessed. The recess shall not be less than 75mm below
the surface of the surrounding or adjacent floor. Rain water run-off from the
surrounding of the wash area shall not be discharged into it.

11.4 Every wash area shall be provided with either a floor trap connecting to a gully
trap or a gully trap connecting directly to an inspection chamber.

11.5 No wash area shall be sited under the caves of the roof.

12 Grease Trap

12.1 Every canteen, cooked food center and restaurant shall be provided with a grease
trap.

12.2 Grease trap or inspection chamber shall not be sited within areas where food
is prepared, cooked, stored or served.

12.3 For wastes from canteen, cooked food center and restaurant, separate cast
iron discharge stack and pipe shall be provided.

13 Miscellaneous Provisions

13.1 The floors or balconies, common corridors, common verandahs, covered play
areas, covered car parks, refuse-chutes, bin centers and other like places of any
building, where sullage water flows, shall be recessed not less than 75mm below
the surfaces of the surrounding or adjacent floors.

13.2 Sufficient floor traps and gully traps shall be provided for connections to the
Inspection chamber.

13.3 Where it is not possible for the floors to be recessed, curbs of 75mm by 75mm or
scupper drains shall be provided around the perimeter of the floors.
 Page 6
14 Drainage System for Temporary and Semi-Permanent Houses provided Pursuant to
Notices served under The Water Pollution Control and Drainage Act, 1975

14.1 Plastic inspection chamber is required in this system except for the last inspection
chamber before the connection to the sewerage system.

14.2 Every branch drain-line shall connect to the plastic inspection chamber.

14.3 An inspection chamber shall be provided for every main drain-line at intervals of
not more than 30 metres and at every change of direction.

15 Material and Component

15.1 All requirements as specified in Part IV shall be complied with.

 Page 7
CODE OF PRACTICE

ON

SANITARY PLUMBING AND DRAINAGE SYSTEM

PART II : SANITARY PLUMBING ABOVE GROUND

1. Design of Sanitary Plumbing (6), (7) & (8)

1.1 The sanitary plumbing system for any premises shall be designed to carry away
sewage and waste water from the building quickly so as not to create any nuisance
or risk of injury to health.

1.2 No sanitary plumbing system shall be used to convey rain-water.

1.3 The “one pipe system” is recommended in the design of the sanitary plumbing
system

1.4 The “single stack system” is recommended for residential buildings up to five
storeys high.

2. Trap

1.5 Every inlet to the discharge pipe or discharge stack shall be properly trapped to
prevent the entry of foul air from the drainage system into the building.

1.6 Every trap for soil sanitary appliance and floor trap shall have a water seal of not
less than 50mm.

1.7 Every trap with an outlet of less than 75mm in diameter shall have a water seal of
not less than 75mm.

1.8 Every trap shall be accessible and so designed as to facilitate cleaning.

3. Discharge Pipe and Discharge Stack (6), (7) & (8)

3.1 Every discharge stack shall have an uniform diameter of not less than 100mm
 throughout its entire length.

3.2 Every discharge pipe and discharge stack shall be fitted with access covers, bends,
branches, junctions and other fittings for connections from the sanitary appliances
and floor traps.

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3.3 Every access cover shall be so fixed in a manner for easy access to facilitate
maintenance and also away from hidden corners.

3.4 Every discharge pipe and discharge stack shall be securely supported or fixed to
the wall of a building. Such support or fixing shall not be more than 1.8 metres
apart and shall be properly aligned.

3.5 The discharge stack shall not form any bend or angle throughout its length unless
the design dictates otherwise.

3.6 Where discharge pipe or stack passes through wall or floor, the area surrounding
the pipe or stack shall be water-tight.

3.7 For seven-storey or higher multi-storey buildings, the discharge pipe serving the
second storey shall be connected to a separate discharge stack. This stack
shall be extended to serve as ventilating stack.

4. Connection of Discharge Stack to Branch drain-line (8)

4.1 Every discharge stack shall be connected directly to the inspection chamber.
Where individual connections of discharge stacks are impracticable, a common
discharge pipe to suit connection to inspection chamber may be permitted.

4.2 The bend at the base of discharge stack shall be of large radius, at least 200mm
radius to the center line, but preferably two 45o large radius bends shall be used.

5. Termination of Discharge Stack and Ventilating Stack (6) & (7)

5.1 The top end of every discharge stack or ventilating stack shall be provided with a
guard (i.e. wire ball for cast iron ventilating stack and uPVC cowl for uPVC
ventilating stack) not less than 450mm above the eaves of a sloping roof or
150mm above a flat roof without parapet, or in the case of a flat roof with parapet
to the height of the parapet above the roof.

5.2 If a flat roof is used for any purpose other than as a covering to the building, the
discharge stack or the ventilating stack shall be extended at least 2.5 metres above
roof level.

5.3 The top end of the discharge stack or ventilating stack above the roof shall be at
least 3 metres away from any window or opening of adjoining building in the
horizontal direction.
 Page 9
5.4 If at any time the Director is of the opinion that the top end of the discharge stack
or ventilating stack is not at such a level or position as to give efficient ventilation
or there is a likelihood of contamination or nuisance to an adjoining building, the
Director may require such stack to be extended to a level or re-fixed in a new
position as he may think fit.

5.5 Where a stack passes through the roof the area surrounding the stack shall be
water-tight.

6. Ventilating Pipe and Main Ventilating Stack (7) & (8)

6.1 Where more than one trap is connected to a discharge pipe or discharge stack,
each trap shall be provided with a ventilating pipe of not less than 50mm in
diameter.

6.2 Every ventilating pipe shall be constructed upwards individually or be connected

to a main ventilating stack. Such connection shall be above the spill over level of
the soil sanitary appliance or floor trap served by such ventilating pipe.

6.3 The top end of every ventilating pipe or main ventilating stack shall either
terminate as high as the discharge stack or connect into the discharge stack at a
point not less than 150mm above the top of the highest soil sanitary appliance or
floor trap.

6.4 Cross venting between the ventilating stack and the discharge stack shall be made
at every ten storeys.

6.5 The lowest cross venting between the ventilating stack and the discharge stack
shall be fixed at a point not less than 225mm below the lowest discharge pipe
connection.

7. Jointing of Pipe

7.1 Every joint in sanitary plumbing shall be made air-tight and water-tight and shall
remain so during use.

7.2 No jointing material shall protrude inside the bore of the pipe.

7.3 Joint for cast iron pipes shall be made as follows:-

 (a) Spigot and socket cast iron pipes shall be packed firmly with spun yarn, and
then tightly caulked to not less than two-third of the depth of the socket with
molten lead or fibrous lead yarn.

Page 10
(b) Alternative jointing materials made from asbestos fibres combined with
cementitious material may also be used for jointing cast iron pipes. These
materials shall be introduced dry into the previously wetted socket and
caulked with heavy hammer blows, keeping the caulking tool moist by
dipping in water.

(c) Rubber ring joint may also be used for jointing cast iron pipes.

7.4 Solvent cement joint for uPVC pipes shall be made as follows: -

(a) The spigot end of the pipe shall be cut square and all burrs removed from the
outside and inside edges thereof.

(b) The spigot end of the pipe shall be marked with a pencil line at a distance
equivalent to the depth of the socket in fittings.

(c) The joint shall be tested for dry fit.

(d) The area between the penciled mark and the pipe end and also the inside of
the socket shall be cleaned and degreased with a cloth moistened with a
cleaning fluid.

(e) A coating of solvent cement shall be applied evenly to the marked section of
the spigot end of the pipe and to the mating internal surface of the socket and
left until touch-dry. A similar coating of the solvent cement shall then be
applied to the marked section of the spigot end of the pipe and a lighter coat to
the socket. Whilst the surfaces are still wet, the pipe end shall then be inserted
and bottomed into the socket.

(f) After jointing the joint shall be held firmly for a period of 30 seconds and not
disturbed for at least 5 minutes.

7.5 Rubber ring joint for uPVC pipes shall be made as follows: -

(a) The spigot end of the pipe and the inside of the socket shall be cleaned.

(b) The outside of the pipe end to be inserted into the socket shall be chamfered
with a taper of approximately 15 degrees and the depth of the socket shall also
be marked on the spigot end of the pipe by means of a pencil.
 (c) The rubber ring shall be placed in its housing in the socket ensuring that it
seats evenly by running the fingers completely around the inside of the socket.

(d) The spigot end of the pipe shall be coated with a lubricant.

Page 11
(e) The spigot end of the pipe shall be inserted into the socket in a straight line
and pushed firmly through the rubber ring. The spigot end shall then be
withdrawn from the socket a distance of 10mm unless otherwise
recommended by the manufacturer.

(f) The socket end of the pipe shall be firmly held during the jointing to prevent
joints previously assembled from closing up.

8. Sewage Divertor or Sewage Ejector or Other Pumping Appliance

8.1 For wastes collected from canteen, cooked food center and restaurant located
below surrounding ground level, sewage divertor shall be provided.

8.2 For domestic wastes collected below surrounding ground level, sewage ejector
shall be provided.

8.3 For waste water from covered car park below ground level, sewage ejector or any
other approved system of pumping shall be provided.

8.4 Where a sewage divertor or sewage ejector is required a room of minimum size
3.0 metres by 3.0 metres shall be provided.

9. Access to Pipeworks

9.1 Every pipework enclosure such as a duct or casing shall be of suitable sizes and
provided with ready access for maintenance, painting, testing and cleaning
thereof.

9.2 No pipe other than the ventilating pipe or ventilating stack shall be encased in
columns, beams or walls. Where encasing is required the pipes shall be
accommodated in ducts with access openings to the access covers.

10. Testing

10.1 The Sanitary plumbing system shall be tested either by means of an air test,
smoke test or water test for soundness of the installation.

11. Painting
 11.1 After testing, the pipework of the sanitary plumbing system may be painted to any
suitable colour.

12. Material and Component

12.1 All requirements as specified in Part IV shall be complied with.

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CODE OF PRACTICE

ON

SANITARY PLUMBING AND DRAINAGE SYSTEM

PART III : SANITARY APPLIANCE

1. Sanitary Appliance

1.1 Every sanitary appliance installed in any premises shall be connected to the
sanitary plumbing and drainage system.

2. Connection of Soil Sanitary Appliance

2.1 The discharge from a soil sanitary appliance shall pass through at least one trap
having a water seal of not less than 50mm before connecting to a branch drain-
line on ground floor or to a discharge pipe on upper floor.

3. Water Closet

3.1 Every water closet shall connect to a branch drain-line on ground floor or to a
discharge pipe on upper floor.

3.2 Every water closer shall be firmly bedded in cement mortar or by other approved
method of fixing

3.3 Where an oriental water closet is installed in a combined bath and water closet
compartment, it shall be fixed at least 75mm above floor level.

3.4 The jointing of the water closet to the discharge pipe shall be done either in
cement mortar, by rubber ring or other method of jointing approved by the
Director.

4. Flushing Cistern

4.1 Every flushing cistern shall be firmly fixed to the wall by either bolts and nuts,
brackets or other approved means.
 4.2 Where brackets or other approved means are used, they shall not protrude
beyond the bottom width of the cistern and shall not have any sharp edges.

4.3 No oriental water closet shall be fixed with a flushing cistern located at a height
less than 1.5 metres.

Page 13
4.4 The flush pipe connecting a flushing cistern to a water closet shall be fixed as
straight as possible and shall not be less than 32mm in diameter if the
bottom of the cistern is fixed 1.5 metres or more above the top of the water
closet.

4.5 Every flush pipe shall not be less than 38mm in diameter if the bottom of the
cistern is fixed less than 1.5 metres above the top of the water closet.

4.6 Every flush pipe from the cistern to the oriental water closet shall be securely
fixed to the wall.

4.7 No direct connection from any water service pipe shall be made to any part of the
soil sanitary appliance other than a connection through the flushing cistern.

5 Urinal

5.1 Every urinal installed at ground floor shall connect directly to a branch drain-line
by means of trap 100mm in diameter.

5.2 A group of bowl urinals connected in series may be discharged to a common soil
pipe of not less than 75mm in diameter or to a common channel for connection as
in sub paragraph 5.1.

5.3 Where a group of bowl urinals are provided, a reasonable number shall be
allocated for use by children. The maximum height of bowl urinals shall be as
follows:
For adults : 550mm
For children : 380mm

5.4 The floor in front of a slab urinal shall be raised above the general floor level to
form a step and the width of such raised portion shall not be less than 300mm.

5.5 A urinal trap shall be provided to serve a maximum of 2.5 metres in length of slab
urinal or 4 bowl urinals.

5.6 The channel to urinals shall have a fall of not less than 1 in 100 towards the
discharge outlet.
 5.7 The outlet to urinals shall be fitted with a gunmetal or brass dome-shaped
removable grating.
5.8 At least one flushing cistern shall be fixed for every 2.5 metres of slab urinal or 4
bowl urinals in series.

5.9 Flushing shall be by a horizontal perforated sparge pipe 19mm in diameter or by

individual spreaders.
5.10 Flush pipe for urinals shall not be less than 25mm in diameter.

Page 14
6. Bidet

6.1 Every bidet installed at ground floor shall connect to a branch drain-line by means
of a trap 100mm in diameter.

6.2 Every bidet installed at upper floor shall connect to discharge pipe by means of a
trap 75mm in diameter.

6.3 Water for the flushing of the bidet shall not be supplied directly from the water
main.

7. Special Soil Sanitary Appliance for Hospital

7.1 Approval of the Director shall be obtained for the use of any special soil sanitary
appliance not covered under this part.

8. Fixing of Waste Sanitary Appliance

8.1 Every waste sanitary appliance which is suspended, shall be fixed to the wall by
means of brackets which are built or screwed into the wall.

8.2 Every floor mounted waste sanitary appliance shall be provided with pedestal,
foot and leg.

8.3 Any sink and wash basin may be mounted on a cabinet.

8.4 All fixing screws shall be corrosion resistant.

8.5 All joints between any waste sanitary appliance and the abutting wall shall be
water-tight.

9. Connection of Waste Sanitary Appliance

9.1 Every waste sanitary appliance shall be provided with a waste fitting and trap for
connection to the waste pipe.

9.2 The minimum internal diameter of a waste pipe for the various waste sanitary
appliances shall be as follows:
 Page 15

Min. Internal Dia. Of

Min. Internal Dia. of Waste Common Waste Pipe in
Type of Appliance
Pipe in mm mm for more than One
Appliance Connected

Wash Basin 32 50 (for up to 5 basins

connected in series)
Sink (single or double 38 50
bowl)

Laboratory sink 38 50

Bath 38 -

Foot bath 38 -

Wash tub 50 75

Wash trough 50 75

Drinking fountain 25 50

9.3 The waste pipe shall connect to the floor trap above the water seal of the trap.

9.4 The waste pipe for waste sanitary appliance fixed outside the building may
connect directly to a gully trap.

10. Floor Trap

10.1 Every floor trap at ground level shall be connected to a gully trap and the length
of the waste pipe shall be as short as practicable.

10.2 Every floor trap at upper floor level shall be connected to a discharge pipe.

10.3 Every floor trap shall be located inside the building wherever practicable.
 10.4 The outlet of the floor trap shall not be less than 75mm in diameter.

10.5 Any riser to a floor trap shall be of the same size as the opening of the trap.
10.6 The height of a riser to any floor trap shall not be more than 600mm from the top
of the grating to the bottom of the trap.

10.7 The grating for a floor trap shall be fixed at least 5mm below the lowest point of a
graded floor.

Page 16
11. Bathroom or Shower Compartment

11.1 The floors of any bathroom or shower compartment shall be recessed not less than
25mm below the level of the surrounding or adjacent floors or enclosed by a kerb
which shall be not less than 25mm in height and not less than 50mm in width.

11.2 The floor shall be graded towards a floor trap sited away from the entrance of the
compartment.

11.3 For group showers, a floor trap shall be provided to serve a maximum of 5
showers. A channel not less than 100mm in width and 50mm in depth at a grade
of 1 in 100 shall be provided.

12. Material and Component

12.1 All requirements as specified in Part IV shall be complied with.

 Page 17

CODE OF PRACTICE

ON

SANITARY PLUMBING AND DRAINAGE SYSTEM

PART IV: MATERIAL AND COMPONENT

1. Material and Component

1.1 Every material and component used in the construction of sanitary plumbing and
drainage system described in this Code shall be of a type, size, brand, quality and
workmanship approved by the Director.

2. Procedure for the Approval of Sanitary Appliance/Fitting

2.1 Every application for approval for Sanitary appliance/fitting shall be made by the
applicant to the Director in writing.

2.2 The applicant shall deliver to the Director such samples of the sanitary
appliances/fittings and such other information in connection therewith as the
Director may require.

2.3 The Director may require one or more samples of the sanitary appliances/fittings
to be delivered to the Singapore Institute of Standards and Industrial Research
(SISIR) for examination and testing and the applicant shall pay such fees as SISIR
may determine for such examination and testing.

2.4 The Director may at any time cancel any approval given in respect of any sanitary
appliance/fitting if:

(a) the sanitary appliance/fitting is found to be unsafe or unsuitable for use:

(b) the design, material or construction of the sanitary appliance/fitting is changed
or modified without the approval of the Director; and
(c) the person to whom approval was given has contravened or failed to comply
with any of the requirements.
 2.5 Every sanitary appliance shall bear the brand name/trade mark and the country of
origin at a conspicuous position, which can be clearly identified after installation.

3. Prohibition of Use of Sanitary Appliance / Fitting

3.1 No person shall install any sanitary appliance/fitting unless the Sanitary
appliance/fitting has been approved by the Director.

Page 18
CODE OF PRACTICE

ON

SANITARY PLUMBING AND DRAINAGE SYSTEM

PART V : PROCEDURE FOR APPLICATION TO CARRY OUT SANITARY

PLUMBING AND DRAINAGE SYSTEM

1. Sketch Plan

1.1 When making application, the registered plumber shall ensure that the following
accompany the application:

(a) Application Form ‘A’ in duplicate (see Appendix 9)

(b) Conditions for carrying out Sanitary Plumbing & Drainage System and Sewer
Connection in duplicate (see Appendix 10).

*(c) Where no road opening is involved, six (6) copies of location/site plan; plans
and sections.

*(d) Where road opening is involved, twelve (12) copies of location/site plans;
plans and sections and Road Traffic Sign Plans.

(e) Plans and sections shall show the following:

i) Scale to which the plans and sections are drawn;

ii) details of any sanitary plumbing and drainage system which shall
be coloured in blue, red and yellow for existing, proposed and to
be abandoned items respectively;

iii) every appliance to be installed, repaired or replaced;

 iv) every compartment which is to have or has any sanitary appliance
and which is to be constructed or repaired; and

v) signatures of the Owner/Developer, or the Occupier and Land

Owner, the Architect/Professional Engineer, if any and the
Registered Plumber shall be endorsed on the plans.
________________________________________________________________________

*To comply with where applicable

+ Subject to revision without notice

Page 19
*(f) Payment of Sanitary Permit Fee of +$25.00 per unit.

*(g) Payment of Cost of Y-junction/advance sewer connection.

*(h) In the case of temporary toilet in sewered area, payment of a deposit of

+$300.00 for sealing off sewer connection,

*(i) In the case of temporary toilet for construction site, letter of undertaking by
Firm/Developer to demolish temporary toilet/temporary septic tank after
completion of the project (see Appendix 11)

1.2 On approval of the Sanitary Application, the Registered Plumber shall notify
Sewerage Department of his intention to commence work by submitting Form B
in duplicate (see Appendix 12).

1.3 The Sanitary Plumbing and Drainage System shall be carried out in accordance
with The Sanitary Plumbing and Drainage System Regulations, 1976, the Code of
Practice on Sanitary Plumbing and Drainage System.

1.4 The Sewerage Department shall be notified of any proposed deviation of work
from the approved plan and approval must be obtained before proceeding with the
work.

1.5 The Sewerage Department shall be consulted on problem which may arise during
the course of construction of the sanitary plumbing and drainage system.

1.6 On satisfactory completion of the work, the registered plumber shall submit
Certificate of Supervision Form C2 (see Appendix 13) and the Registered
Plumber shall arrange with the Sewerage Department for final inspection of the
completed work.

1.7 In cases of withdrawal of sanitary application/permit, the registered plumber is

required to give an explanation stating the reasons and the percentage of work
completed. Withdrawal Form D (see Appendix 14) shall be submitted in
duplicate.
 1.8 Where the trench to be excavated exceeds 4 metres in depth, it shall be
constructed in accordance with the design and drawings of a Professional
Engineer.

2. Building plan

2.1 When making application, the procedure as specified in Section 11 of the

Sewerage Procedures and Requirements Book shall be complied with
________________________________________________________________________
*To comply with where applicable
+ Subject to revision without notice

Page 20
2.2 In cases of withdrawal of the sanitary application/permit, the registered plumber is
required to give an explanation stating the reasons and the percentage of work
completed. Withdrawal Form D (see Appendix 14) shall be submitted in
duplicate.
 Page 21
CODE OF PRACTICE

ON

SANITARY PLUMBING AND DRAINAGE SYSTEM

PART VI : APPENDICES

(A) STANDARD DRAWINGS ON SANITARY PLUMBING AND DRAINAGE

SYSTEM
Appendix 1: ENV/SEW/SAN/1A Layout of Sanitary Drainage System

Appendix 2: ENV/SEW/SAN/2A Ground Floor Branch Drain-line Connection

to Inspection Chamber

Appendix 3: ENV/SEW/SAN/3A Type Bedding for Drain-line

Appendix 4: ENV/SEW/SAN/4A Inspection Chamber

Appendix 5: ENV/SEW/SAN/5A Wash Area

Appendix 6: ENV/SEW/SAN/6A One Pipe System with Ventilating

Arrangement for Six-Storey or Lower Multi-
Storey Buildings

Appendix 7: ENV/SEW/SAN/7A One Pipe System with Ventilating

Arrangement for Seven-Storey or Higher
Multi-Storey Buildings

Appendix 8: ENV/SEW/SAN/8A Below Ground Details (Connection Between

Discharge/Ventilating Stack to Inspection
Chamber
 Page 22
(B) STANDARD FORMS FOR SUBMISSION AND WITHDRAWAL

Appendix 9: Application for a permit to carry out Sanitary Plumbing and

Drainage System under The Sanitary Plumbing and Drainage
System Regulations, 1976 - Form A

Appendix 10: Conditions for carrying out Sanitary Plumbing and Drainage
System and Sewer Connection

Appendix 11: Undertaking by Firm/Developer to Demolish Temporary Toilet

After Completion of Project

Appendix 12: Notice of Intention to Commence/Inspect Sanitary Plumbing and

Drainage System – Form B

Appendix 13: Certificate of Supervision for Sanitary Plumbing and drainage

System – Form C2

Appendix 14: Application for Withdrawal of Sanitary Application/Permit

Page 23