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
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
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:
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
Water charges in Hong Kong (cont’d)
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
Mains water supply
Size of the water mains (from WSD)
Pressure (or head) of water (20 or 30m head)
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
Pressure of water supplies in Hong Kong
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
Hong Kong Waterworks Standard Requirements For
Plumbing Installation in Buildings
http://www.wsd.gov.hk/filemanager/en/content_149/hkwsre.pdf
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
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)
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
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
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
There are at present 3 types of labeling scheme
Showers:
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:
<=9.0 L/min – Grade 1 …>16 L/min – Grade 4
Water Taps:
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
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