Technical Briefing by Water Supply (Network) Department
Introducing Singapore Standard 636:
Code of Practice for Water Services
Marina Barrage
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Singapore Standard 636:
Code of Practice for Water Services
• Publication of Enterprise Singapore
• Periodic review of Singapore Standards by Enterprise Singapore
• Replaces Singapore Standard CP48: Code of Practice for Water
Services
• Review was done in consultation with industry representatives from:
- Association of Consulting Engineers, Singapore
- The Institution of Engineers, Singapore
- Housing & Development Board
- Singapore Plumbing Society
- Singapore Sanitary Water Importers & Exporters Association
- PUB, Singapore’s National Water Agency
www.pub.gov.sg
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Objective of this Review / Update
• Editorial improvements to provide better clarity and readability
• General updates
i. Included other reference standards
(AS/NZS 3500, BS EN 1992-3 etc.)
ii. Incorporated earlier amendments nos. 1 – 4
iii.Reflected latest industry practices
iv. Incorporated latest statutory requirements
• Inclusion of best practices
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Summary of changes
Definitions (Clause number in SS 636)
• Effective capacity (3.5) (New addition)
i. CP 48 - Not indicated
ii. SS 636 - The usable volume of the tank measured from the
top water level to the draw off level of the tank.
• Piping (3.13) (New addition)
i. CP 48 - Not indicated
ii. SS 636 - A network of pipe and fittings.
• Top water level (3.22) (New addition)
i. CP 48 - Not indicated.
ii. SS 636 - The top water level is the water level measured up to at
least 25mm below the warning alarm/invert.
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Summary of changes
• Water service worker (3.25) (New addition)
i. CP 48 - Not indicated.
ii. SS 636 - Plumbers licensed by the Authority and registered
Professional Engineers.
• Removed clauses from CP 48
i. 1.2.22 Water line
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Summary of changes
Services
• Clause 6.4.19 in SS636 vs 2.4.19 in CP 48
i. CP 48 - No potable water pipe should be laid below any non-
potable water pipe. Where unavoidable, the potable water
pipe shall be adequately protected against possible
contamination.
ii. SS 636 - No potable water pipe should be laid below any non-
potable water pipe. Where unavoidable, the potable water
pipe shall be adequately protected against possible
contamination except for fire sprinkler pipes using potable
water as source without joints at the points of pipe crossing.
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Summary of changes
Hot water supply systems
• Clause 6.5.1 in SS636 vs 2.5.1 in CP 48
i. CP 48 - (The Authority allows direct connection of electric or gas
instantaneous water heaters to the service pipes for cold
water supply where applicable provided these heaters
comply with the specifications and requirements of the
manufacturer and the Authority and all other relevant
statutory requirements.)
ii. SS 636 - (…)The design of the water reticulation system shall take
into consideration the minimum operating pressure of such
heater to ensure that satisfactory flow rates at the water
fittings / appliances are achieved.
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Summary of changes
Mode of water supply
• Changes from CP 48 in red
The mode of water supply adopted by the Authority are generally as follows:
Height of Fittings Methods of Supply
(a) Water fittings located up to 25 m above Direct (See Figure 1)
mean sea level
(b) Water fittings higher than 25 m above Indirect supply through high level storage
mean sea level but up to 37 m above mean tank (See Figure 2)
sea level
(c) Water fittings higher than 37 m above Indirect supply through low level tank with
mean sea level pumping to high level tanks (See Figure 3 and
Figure 4)
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Summary of changes
Mode of water supply
• Changes from CP 48 in red
125 mRL +25.00m
PWD datum: Singapore Height
100mRL Datum : 0.00m
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Summary of changes
Storage
• Clause 7.1.14 in SS636 vs 3.1.14 in CP 48
i. CP 48 - (Every isolated compartment of a storage tank shall be
fitted with a) tap for sampling purposes located midway
between the top operating water level and the floor of the
tank or on the outlet pipe from the compartment f the
storage tank. Such a tap shall be under lock and key and
accessible only to authorised persons.
ii. SS 636 - (…) tap for sampling purposes located anywhere
between the top operating water level and the outlet pipe
level or on the outlet pipe from the compartment of the
storage tanks. The tap located on the tank should be made
accessible for sampling purpose. Such a tap shall be under
lock and key and accessible only to authorised persons.
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Summary of changes
• Clause 7.1.15 (a) in SS636 vs 3.1.15 point 1 in CP 48
i. CP 48 - [No storage tank and its associated water pipes and pumps
(where applicable) shall be installed in such a position that:
it is directly below any sanitary pipe, floor trap, sewer pipe,
reclaimed water pipe,] waste pipe or any other pipes
conveying fluids that may cause contamination to the water
in the storage tanks.
ii. SS 636 - […] waste pipe, sprinkler pipe, wet riser pipe or any other
pipes conveying fluids that may cause contamination to
the water in the storage tanks.
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Summary of changes
• Clause 7.1.19 (a) in SS636 vs 3.1.19 point 1 in CP 48, Amendment 4, (8)
i. CP 48 - [For water tanks in developments other than landed
residential premises: the water tanks and their ancillary
equipment shall be housed in an adequately secured and
locked dedicated tank / pump room or located within an
adequately secured and locked enclosure.] The
room/enclosure housing the water tanks and their ancillary
equipment shall be segregated from other services such as
services for telecommunications, lifts or fire-fighting.
ii. SS 636 - […] The room/enclosure housing the water tanks and their
ancillary equipment shall be segregated from other services
such as equipment for telecommunications, lifts, firefighting
or ACMV. The enclosure for water storage tanks shall not be
used for storage of items such as flammable liquids or
chemicals.
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Summary of changes
Storage Tanks
• Clause 7.3.3 in SS636 vs 3.3.3 in CP 48
i. CP 48 - (Storage tanks shall be fixed in such positions that will
enable the interiors to be readily inspected and cleaned, and
where they will not be exposed to high temperature.
Adequate spacing of at least 0.6 m shall be provided all
around the) tank for maintenance and inspection purposes.
ii. SS 636 - (…) sides of the tank with at least 1 m spacing from the top
of the tank to the ceiling for maintenance, repair and
inspection purposes.
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Summary of changes
Appliances
• Self-closing delayed action taps
Changes in clause 8.2.4 in SS636 vs 4.2.3 in CP48 highlighted in red
Table 2 – Maximum allowable flow rates and timing for
self-closing delayed-action taps
Usage Flow Rate Timing
i) Basin 6 L/min 2-3
ii) Basin (public toilets) 2 L/min 2–3
iii) Shower 9 L/min 13 – 15
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Summary of changes
• Handheld bidet spray
Clause 8.3.3 in SS636 (New addition)
i. CP 48 - Not indicated
ii. SS 636 - Handheld bidet spray.
Handheld bidet spray (connected to a flexible hose)
located next to a water closet shall be installed with a
check valve and vacuum breaker. The flow rate of the
handheld bidet spray should not be more than 8 litres
per minute.
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Summary of changes
• Solar heater
Clause 8.3.5 in SS636 vs 4.3.5 in CP 48
i. CP 48 - (The water supply for the solar heating system shall be
derived from a feed tank. Alternatively, the mains pressure
solar water heater may be installed by direct connection to
the service pipe provided that a combined pressure and
temperature relief valve together with a controlling
stopcock), non-return valve and anti vacuum relief valve are
also fitted to the cold water supply side of the heater in
accordance with the specifications and requirements of the
manufacturers.
ii. SS 636 - (...) and an efficient device which will prevent the
siphonage of water back through the inlet are also fitted to
the cold water supply side of the heater in accordance with
the specifications and requirements of the manufacturers.
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Summary of changes
Work on site > Jointing of pipes
• Clause 9.1.1 in SS636 vs 5.1.1 in CP 48
i. CP 48 - All proprietary joints shall be made in accordance with the
manufacturer’s instructions. Care shall be taken to establish
satisfactory jointing techniques for all water service
pipework. When making joints by welding, brazing or
soldering, precautions shall be taken to avoid the risk of fire
and care taken to avoid inhalation of fumes from the jointing
process. Lead based solders shall not be used in potable
water services. All burrs shall be removed from the ends of
pipes and any jointing materials used shall be prevented
from entering the water system. All piping and fittings shall
be cleaned internally and shall be free from particles of
sand, soil, meta filings and chips.
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Summary of changes
Continued from previous slide
ii. SS 636 - All proprietary joints shall be made in accordance with the
manufacturer’s instructions. Care shall be taken to establish
satisfactory jointing techniques for all water service
pipework. When making joints by welding, brazing or
soldering, precautions shall be taken to avoid the risk of fire
and care taken to avoid inhalation of fumes from the jointing
process. Soldering alloys with lead and brazing alloys with
cadmium shall not be used in potable water services. All
burrs shall be removed from the ends of pipes and any
jointing materials used shall be prevented from entering the
water system. All piping and fittings shall be cleaned
internally and shall be free from particles of sand, soil, meta
filings and chips
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Summary of changes
• Clause 9.1.3(c) and 9.1.5(c) in SS636 (New addition)
(Both clauses are similar just copper or stainless steel)
i. CP 48 - Not indicated
ii. SS 636 - Press-fit joints.
Press fit coupling system shall be carried out by means
of a suitable mechanical clamping jaw to crimp a
specially designed copper / stainless steel fitting to a
standard copper / stainless steel pipe. The copper /
stainless steel fitting shall consist of an “O” ring seal.
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Summary of changes
Ductile Iron Pipes > Spigot and socket push-on joints
• Clause 9.1.9.1 in SS636 (New addition)
i. CP 48 - Not indicated
ii. SS 636 - Flexible joint that uses compression of synthetic rubber
gasket to provide a water-tight seal that can
accommodation angular deflection.
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Summary of changes
Water Conservation
• Removal of clause 7.2(c) [partial] from CP48
i. CP 48 - Install constant flow regulators at all wash basin mixers,
shower mixers and bib taps.
ii. SS 636 - Install constant flow regulators at all wash basin mixers,
shower mixers and bib taps.
Please also note the above deletions from CP 48
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Summary of changes
Private water meters
• Clause 11.3 in SS 636 (New addition)
i. CP 48 - Not indicated
ii. SS 636 - Private water meters to measure and monitor the
amount of water use at each water usage areas specified in the second
column of Table 5 shall be installed for non-domestic use with an
estimated average monthly consumption of at least 3000 m3 ……
Snapshot of Table 5
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Summary of changes
Annex A
Inspection and cleaning procedures
• Clause A.1.1.10 in SS636 vs A1.1.10 in CP48
i. CP 48 - All workers involved in the cleaning work shall wash,
clean and disinfect themselves thoroughly before
entering the tank.
ii. SS 636 - All workers involved in then cleaning work shall be
certified by a medical doctor to be free from water-
borne diseases. Workers should be vaccinated or
immunized against water-borne diseases such as
typhoid, cholera and infectious hepatitis.
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Summary of changes
Disinfection procedure
• Clause A.1.2.13 in SS 636 vs A1.2.13 in CP 48
i. CP 48 - Observe procedures A.1.2.1 to A1.2.11 but add
sufficient chemicals to give the water a dose of 500
mg/litre of free chlorine. Then keep the sterilized water
in the tank for at least 2 hours before draining off
completely.
ii. SS 636 - Observe procedures A.1.2.1 to A1.2.11 and add
sufficient chemicals to give the water a dose of 200
mg/litre of free chlorine. Then, keep the disinfected
water in the tank for at least 2 hours before draining off
completely.
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Summary of changes
Annex B – Water Sampling test for leaching of heavy metals
• Entire Annex B in SS 636 (New addition)
i. CP 48 - Not indicated
ii. SS 636 -
Snapshot of Annex B
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Summary of changes
Meters
• Fig in SS 636 vs CP 48 – addition of valve for flushing the manifold pipe
CP 48 SS 636
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Summary of changes
Meters
• Fig notes in SS 636 vs CP 48
i. CP 48 - Permanent unit tags are to be provided.
ii. SS 636 - Permanent unit tags are to be provided and properly
secured upstream of the sub meters.
Additional things to note
• Legal and statutory requirements omitted from the Code
e.g.. “All the firefighting services shall comply with the Public Utilities
(Water Supply) Regulations and ….. In accordance with Singapore Civil
Defence Force”
Has since been replaced with
It is presupposed that firefighting services are in compliance with
applicable statutory and regulatory requirements.
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Q&A
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