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LCQ17: Total Water Management Strategy and related measures

     Following is a question by the Hon Wu Chi-wai and a written reply by the Secretary for Development, Mr Paul Chan, in the Legislative Council today (April 17):


     In 2008, the Government announced the implementation of the Total Water Management (TWM) Strategy for a balanced supply and demand of raw water, through strengthening water conservation and developing alternative water sources, so as to support the sustainable development of Hong Kong.  Regarding the progress of the implementation of the TWM Strategy and related measures, will the Government inform this Council:

(a) of Hong Kong's projected demand for water in each year from 2014 to 2030 based on Hong Kong's current population trend; as the Government indicated in February 2011 that it would conduct a domestic water consumption survey that year and "consider the feasibility of establishing water conservation targets for the medium term and other water saving targets in addition to the total water saving target", of the current progress of establishing such water saving targets;

(b) as the Government indicated in 2008 that it would
"conduct trials in projects of appropriate scale and nature to gather experience and encourage private developers to consider using [reclaimed water]", of the works projects in which pilot schemes on the use of reclaimed water had been carried out by the Government in the past three years, apart from the pilot schemes on the use of reclaimed water at Ngong Ping and Shek Wu Hui for toilet flushing and other non-potable uses, as well as the number of private developers which had participated in such pilot schemes (set out the names of the works projects concerned as well as the contents and results of related pilot schemes);

(c) as the Government indicated in May 2010 that it had implemented some trial schemes in schools and government facilities for recycling grey water and harvesting rainwater for other non-potable uses, of the number of such trial schemes implemented in schools and government facilities since 2009, as well as the related details and effectiveness; as the Government indicated in October 2011 that it had conducted a consultancy study to establish technical standards for recycling grey water and harvested rainwater for non-potable uses, of the progress of such study and the establishment of the technical standards;

(d) of the respective annual water consumption levels of the top five government departments in water consumption and main uses of water consumed (e.g. cleansing of streets or vehicles, irrigation, etc.) in the past three years, and whether such figures had included the water consumption of these departmentsˇ¦ outsourced service contractors;

(e) whether it has separately drawn up short and long term water saving targets as well as guidelines on water consumption for various government departments; if so, of the details; as the Government indicated in May 2010 that it had "planned to commission a consultancy study on water consumption practice of major government departments", of the progress of such study;

(f) as the Government indicated in May 2010 that it was reviewing the water tariff structure to encourage reduction of water consumption, of the outcome of the review and the follow-up policy proposals;

(g) whether it has compiled statistics on or estimated the annual quantity of rainwater discharged to the sea via drainage facilities (e.g. drainage tunnels, flood storage ponds, etc.) or due to overflow from reservoirs; if so, of such figures in each of the past three years; if not, the reasons for that;

(h) apart from the plan to construct an overflow transfer tunnel from Kowloon Byewash Reservoir to Lower Shing Mun Reservoir to conserve water resources, whether the Government studied or implemented other inter-reservoirs overflow transfer schemes in the past five years;

(i) whether it has regularly tested the water quality of the rainwater running through the stormwater drainage system to see if such water is suitable for non-potable uses; if so, of the outcome of such tests in the past three years; if not, whether it will plan to carry out such tests; and

(j) whether currently it has any plan to collect rainwater running through the stormwater drainage system and supply such water to some government departments for non-potable uses, or to conduct related studies; if so, of the details; if not, the reasons for that?



     The Total Water Management Strategy (the Strategy) promulgated in 2008 has mapped out the strategy for a balanced supply and demand of water to support sustainable development in Hong Kong. The Strategy puts an emphasis on containing the growth of water demand through promoting water conservation. The Strategy focuses on two major areas, namely water demand management and supply management. On water demand management, one of the initiatives is to enhance public education on water conservation. Other initiatives include promoting the use of water-saving devices, enhancing water leakage control, and extending the use of seawater for toilet flushing. As regards supply side management, one of the initiatives is to develop the option of seawater desalination. Other initiatives include strengthening the protection of water resources and actively considering water reclamation (through reuse of grey water and rainwater harvesting). We reported the progress of the Strategy to the Legislative Council in May 2010 and October 2011 respectively.

     My reply to the 10 parts of the question is as follows:

(a) Water demand is regularly assessed every one to two years on the basis of various significant statistics related to demographic changes, economic growth, social and economic activities. The Water Supplies Department (WSD) made an assessment in 2012 on the basis of our population reaching eight million by 2030, as projected by the Census and Statistics Department in 2012. In the light of this assessment and the effectiveness of the Strategy's management initiatives, we expect that the total annual potable water demand will increase from 935.43 million cubic metres (mcm) in 2012 to about 1 100 mcm in 2030, representing a reduction of about 200 mcm from the estimated annual fresh water demand of 1 300 mcm in 2030 as projected in 2008.

     The Strategy was launched in 2008 with the objective of reducing domestic water consumption in 2030 by 100 mcm, which is about one half of the above-mentioned 200 mcm estimated reduction in demand.  To this end, the WSD commissioned a consultant in August 2011 to conduct a domestic water consumption survey to identify the public's domestic water consumption pattern in order to formulate a more effective water conservation strategy.  Upon the completion of the survey in 2012, the WSD analysed the findings and drew up various targeted measures to encourage the public to adopt proactive water conservation practices in their daily lives.  The measures include (1) launching the "Let's Save 10L Water" Campaign, which aims to encourage the public to reduce daily water consumption by at least 10 litres per person in the medium term.  After inviting 1 000 students and their families to participate in this 6-month campaign in March this year, the WSD also plans to expand the Campaign to the whole community in 2014. Other targeted measures include: (2) planning for the setting up of a Water Resources Education Centre to step up education for the younger generation on water conservation. In this connection, a temporary centre was formally opened in the WSD's Mongkok Office in March this year and invitations to visit the Centre have been extended to primary schools; (3) A roving exhibition on "Save Water, Cherish the World" is being conducted in housing estates and shopping malls to promote water-saving habits; and (4) Water-saving tips are published in various languages and distributed to foreign domestic helpers and home helpers.

(b) On substituting fresh water resources with alternatives for non-potable purposes, the WSD has started to supply seawater for toilet flushing as early as in the late 1950s. At present, 80 per cent of the community has access to seawater for toilet flushing. The percentage is set to reach 85 per cent when the seawater supply networks at Pokfulam, Yuen Long and Tin Shui Wai become available around 2014. We have also commenced planning for a seawater supply network for Tung Chung.  Using seawater for toilet flushing will not only bring considerable savings in freshwater resources but is also more cost-effective when compared with other alternative water resources, such as reclaimed water.

     Generally, the cost of raising the quality of treated effluent discharge to the level of reclaimed water is higher than supplying seawater for toilet flushing, making the use of reclaimed water not cost-effective. However, for those areas that are far from the sea, such as Sheung Shui and Fanling, the costs of installing seawater supply networks for toilet flushing are higher. Separately, to support the development of North East New Territories New Development Areas, the Drainage Services Department (DSD) needs to expand Shek Wu Hui Sewage Treatment Works and upgrade its treatment technology to cope with the additional effluent load as well as to comply with the standard set by the Environmental Protection Department for discharging to Deep Bay. The WSD seized this opportunity to jointly study with the departments concerned on the feasibility of improving the quality of effluent treated to tertiary treatment level to be discharged from the treatment works project to the level of reclaimed water.  The findings show that supplying reclaimed water to these areas is cost-effective, as the additional treatment processes required are relatively simple. The WSD has taken forward the planning work accordingly. We expect that it will take eight years from planning to commencing supply of reclaimed water.

     Further, in the past years, the DSD has conducted systematic tests on reclaimed water produced from treated effluent at some of its sewage treatment works, including the Sha Tin Sewage Treatment Works. The reclaimed water so produced is used inside the treatment plant for cleansing sewage treatment facilities and some floor areas, flushing toilets, irrigating plants, and diluting chemicals for sludge treatment. In addition, the flushing toilets of Lo Wu Correctional Institution, opened in 2010, and a number of converted aqua privies also use reclaimed water for toilet flushing.

     Producing reclaimed water from treated effluent requires specialised engineering technology and entails a higher cost, making it not cost-effective in many cases.  As such, the WSD is not aware of any reclaimed water project launched by a private developer in the past three years.

(c) To date, the Architectural Services Department has installed rainwater harvesting and recycling systems for 33 schools and government facilities, such as hospitals, government quarters and sports grounds, and provided a grey water recycling system for irrigation purpose at the Electrical and Mechanical Services Department Headquarters. These systems have come into operation in succession. A review of their effectiveness is underway.

     The WSD has also completed a consultancy study on establishing the technical and water quality standards for recycling grey water and harvested rainwater for non-potable uses. It has also consulted relevant government departments and stakeholders (including non-government organisations) and incorporated their comments in refining the technical and water quality standards.

(d) The annual water consumption of the top five government departments in water consumption in the past three years is shown in the annex.

     The major water uses of these government departments include swimming pools, irrigation, street and facility cleansing, potable water and sewage treatment, and personal hygiene.

(e) The WSD commissioned a consultant in 2010 to review the water consumption practices in its installations and develop water saving guidelines. The WSD is currently reviewing the water consumption practices in the Leisure and Cultural Services Department's parks and swimming pools as well as the Food and Environmental Hygiene Department's markets, street cleaning and refuse collection points, with a view to developing water saving proposals for these facilities and operations. The WSD is discussing with the relevant departments ways to optimise their operations and facilities to implement these water saving proposals and achieve water conservation without compromising the level of services to the public. The WSD will gradually extend the scope of review to other departments that have relatively high water consumption.

(f) We briefed the Legislative Council Panel on Development at its meeting in May 2010 on a water tariff structure review that aimed to encourage reduction in water consumption. Subsequently, we considered it necessary to look further into the water consumption pattern of local households in order to formulate more effective water conservation strategies. To this end, the WSD completed a domestic water consumption survey in 2012 and, after analysing the findings, drew up various targeted measures. Please refer to part (a) for details.  We will keep reviewing the effectiveness of these measures and the data collected in the process will provide useful input for the review on water tariff structure. The provision of government services is generally charged in accordance with the "user pays" principle. To prevent these "user pays" services being turned into heavily subsidised services, the Government will review them systematically.  Appropriate fee revisions will be made as and when necessary.  But there will not be substantial revisions at one go to avoid affecting people's livelihood.  The Government will also strictly control the costs and reduce the need for increasing fees and charges as far as possible.  

(g) The total quantities of rainwater discharged from the DSD's flood storage tanks in Tai Hang Tung and Sheung Wan are about 1.1 mcm, 0.8 mcm and 0.2 mcm in 2010-11, 2011-12 and 2012-13 respectively. The overflow from small reservoirs during heavy rainstorms are 25.04 mcm, 0.3 mcm and 15.5 mcm in 2010-11, 2011-12 and 2012-13 respectively. Such overflow is a result of operational constraint instead of wastage.

(h), (i) & (j) Apart from increasing raw water yield through the Inter-Reservoirs Transfer Scheme at Kowloon Byewash Reservoir and Lower Shing Mun Reservoir, we have also studied re-using rainwater collected by drainage tunnels and flood storage tanks.

     To reduce the flooding risk in urban areas, the DSD has adopted the interception approach and constructed drainage tunnels in Tsuen Wan, Lai Chi Kok, Kai Tak and Island West. In the course of the related engineering studies, the DSD's consultant examined various re-use options in terms of economic viability and technical feasibility.  As all options required huge capital investments in additional tunnels and/or pipeworks and pumping facilities, the consultant concluded that re-using rainwater collected in these drainage tunnels networks would not be cost-effective. In addition, the flood storage tanks in Tai Hang Tung and Sheung Wan operate on the principle of temporarily storing some of the rainwater collected upstream and limiting discharging the rainwater downstream. For effective flood prevention, the rainwater in flood storage tanks must be discharged as soon as possible after a rainstorm to prepare for the next rainstorm. Re-using stored rainwater requires construction of additional storage tanks and associated water transfer facilities. As these facilities will only be used several times a year during rainstorms, their cost-effectiveness is doubtful.

     Rainwater running through developed areas would be contaminated by the filth on the surfaces of buildings and roads. The filth is the result of exhaust gases from vehicles travelling on roads, bird droppings on rooftops or animal excreta on the ground. To protect public health, the harvested rainwater must be treated before it can be recycled and used safely. As such, the treatment cost is another factor that should be considered.

     As mentioned in part (b) above, 80 per cent of the local population has access to seawater supply for toilet flushing. This translates into a saving of about 273 mcm freshwater each year, far higher than the volume of rainwater collected by drainage tunnels each year.  As an example, it is estimated that the annual volume of rainwater collected at Tsuen Wan drainage tunnel is only equivalent to about 0.5 per cent of the seawater used for toilet flushing in Hong Kong each year. Given the small volume of rainwater in stormwater drains that collect surface runoffs from developed areas, it is not cost-effective to treat the collected rainwater for non-potable uses.

Ends/Wednesday, April 17, 2013
Issued at HKT 16:53


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