BBSE2001/BBSE2401
Utility Services
Water Supply in Hong Kong
Dr. Benjamin P.L. Ho
(benjamin.ho@hku.hk)
Topics to include:
 Water Supply in Hong Kong
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Water Quality & Conservation
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Source of water and annual consumption
Water treatment and Supply distribution
Total water quality management
Water conservation scheme
Water Supply in
Hong Kong
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Water sources
Water resources in HK
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Rainfall from natural catchment + supply from Guangdong
89% of water demand is supplied by water from Guangdong
(2011)
818Mm3 from Guangdong + 105 Mm3 from natural catchment
– total 923 Mm3 (2011 data)
Sea water for flushing toilets
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270 Mm3 (2011data)(for 5.55M people)
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(Source: Water Supplies Department, www.wsd.gov.hk)
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(Source: Water Supplies Department, www.wsd.gov.hk)
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(Source: Water Supplies Department, www.wsd.gov.hk)
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(Source: Water Supplies Department, www.wsd.gov.hk)
Existing seawater
flushing situation &
proposed extensions
Water treatment
Water for human consumption must be:
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Free from harmful bacteria & suspended matter
Colorless
Pleasant to taste
For health reasons, moderately ‘hard’ (CaCO3)
Water storage & treatment process to ensure good
water quality
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Complies with World Health Organization (WHO) guidelines
for drinking water
Protection of Source
(e.g. in reservoirs)
Coagulation + Segmentation
(mixing & clarifying)
Filtration
(e.g sand filters, pressure filters)
Sterilization
(e.g. by chlorine)
Water Softening
(e.g. by lime soda)
Analysis of Water
(e.g. chemical, physical & bacteriological)
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Typical water treatment process
The water treatment process
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(Source: Water Supplies Department, www.wsd.gov.hk)
Water Charges
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(Source: Annual Report, Water Supplies Department, 2010-2011)
Water Charges
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Water charges in Hong Kong (cont’d)
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Sewage charges
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For domestic consumers: at a 4-month interval: $2.05 per m3
(effective 1.4.2013) with an exemption for the first 12 m3
For trade, business and manufacture consumers: $2.05 per m3
Some trades are eligible for 30% discount (e.g. bleaching & dyeing,
restaurants, soft drinks & ice-making industries)
For 30 types of trade/business/manufacture which discharge trade
effluent, the consumer shall also pay a Trade Effluent Surcharge by the
Drainage Services Department.
Water supply distribution
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Mains water supply
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Size of the water mains (from WSD)
Pressure (or head) of water (20 or 30m head)
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Example: 75 mm diameter pipe fed from both ends or
100 mm diameter pipe fed from one end
Min. head of 30 m for firefighting purposes
Max. head of 70 m to limit wastage and pipe noise
A ring circuit & a grid of pipes
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To increase reliability & facilitate maintenance
Ring main distribution
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(Source: Hall, F. and Greeno, R., 2007. Building Services Handbook)
Water supply distribution
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Pressure of water supplies in Hong Kong
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Fresh water supply: 20 mH (metres head)
Salt water supply: 15 mH (metres head)
They are maintained in the distribution systems except at
their extremities
Note:
1mH = 1m of water column = 9,810Pa
1 atm pressure = 1 bar = 101,325Pa = 10.3mH (approx.)
For simplicity of calculation: 1 bar = 10mH = 100kPa
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Installation Requirements
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Hong Kong Waterworks Standard Requirements For
Plumbing Installation in Buildings
http://www.wsd.gov.hk/filemanager/en/content_149/hkwsre.pdf
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Handbook on Plumbing Installation for Buildings
http://www.wsd.gov.hk/en/plumbing_and_engineering/installation_requirem
ents/handbook_on_plumbing_installation/index.html
(http://www.wsd.gov.hk/en/plumbing_and_engineering/installation_requiremen
ts/index.html)
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Water Quality &
Conservation
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Water quality & management
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Treated water supplied by WSD at the connection points
fully complies with the WHO guidelines for drinking
water
Quality Water Recognition Scheme for Buildings
(launched in 2002 by WSD)
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To encourage building owners to maintain their plumbing
systems properly
There are 3 grades of certificates:
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Blue Certificates: New participation or continuous participation with
less than 3 years
Silver Certificates: Continuous participation 3-5 years
Gold Certificates: Continuous participation >= 5 years
Recommended practices for water quality
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Regular maintenance – water tank cleaned every 3
months, proper and well maintained water tank covers
Prevent contamination, proper cleaning of filters /
purifiers
Use of suitable materials for pipework
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no more unlined GI pipes,
use only approved copper, ductile iron, stainless steel, GI with
lining or PVC pipes
Water Conservation
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Water is a very scarce resource, but in need by every
living creature on this planet
Every day water consumption is huge
Water are not used effectively
So, how can we save water?
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Some ideas from WSD…
(http://www.wsd.gov.hk/en/education/water_conservation/wate
r_saving_tips/index.html)
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(Source: Water Supplies Department, www.wsd.gov.hk)
Voluntary Water Efficiency Labeling Scheme
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There are at present 3 types of labeling scheme
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Showers:
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Non-mixing type
<=2.0 L/min – Grade 1 …>6.0 L/min – Grade 4
Mixing type
<=5.0 L/min – Grade 1 …>9.0 L/min – Grade 4
Washing Machines:
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<=9.0 L/min – Grade 1 …>16 L/min – Grade 4
Water Taps:
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Labeling Scheme on Showers for Bathing (09/2009)
Labeling Scheme on Water Taps (09/2010)
Labeling Scheme on Washing Machines (03/2011)
Labeling Scheme on Urinal Equipment (03/2012)
Category 1 (Horizontal drum type washing machines)
<=9.0 L/kg/cycle – Grade 1 …>13.0 L/kg/cycle – Grade 4
Category 2 (Impeller type or agitator type washing machines)
<=16.0 L/kg/cycle – Grade 1 …>22.0 L/kg/cycle – Grade 4
Urinal Equipment:
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<=1.5 L/cycle – Grade 1 … >4.5 L/cycle – Grade 4