LCQ10: Management of and tapping for fresh water resources
Following is a question by the Hon Lau Kwok-fan and a written reply by the Secretary for Development, Mr Eric Ma, in the Legislative Council today (May 10):
There are views that there are factors destabilising the supply of Dongjiang water, which is the main source of fresh water for Hong Kong, including global climate changes which lead to decreased rainfall and the increasing demand for fresh water resources from a number of places on the Mainland. As such, the Government should properly manage and actively tap for fresh water resources to ensure an adequate fresh water supply in Hong Kong. In this connection, will the Government inform this Council:
(1) of (i) the number of households and (ii) population which currently use fresh water for toilet flushing, and (iii) the annual quantity of fresh water so used, with a breakdown by District Council district; the current production cost per cubic metre of fresh water;
(2) given that the authorities will, by taking the opportunity of the planned expansion of the Shek Wu Hui Sewage Treatment Works (SWH STW) and upgrading of its sewage treatment technology, further process the tertiary treated effluent of SWH STW to make it meet the water quality standards for reclaimed water for use by residents of the North East New Territories for non-potable purposes (such as toilet flushing), of the progress and expected completion date of the relevant work; upon the comprehensive upgrading of the sewage treatment technology, (i) the quantity of fresh water used originally for toilet flushing that can be saved each year, and (ii) the production cost per cubic metre of the further processed effluent, as estimated by the authorities;
(3) of the production cost per cubic metre of fresh water in the first year upon the commissioning of the Tseung Kwan O Desalination Plant, as anticipated by the authorities based on the price indexes for 2017;
(4) of the details of the facilities currently used in Hong Kong for reusing grey water (i.e. water collected from bathrooms, wash basins and kitchen sinks, etc.) and harvesting of rainwater (set out such information by District Council district); whether the authorities will conduct a study on treatment of harvested rainwater for potable uses;
(5) given that reservoir overflow occurred in the past, resulting in the discharge of fresh water into the sea, and the authorities are reviewing the Inter-reservoirs Transfer Scheme, of the details and the latest progress of the relevant work; and
(6) given that bursts of underground fresh water mains have occurred frequently (e.g. seven bursts of fresh water mains occurred in Kwai Tsing District in the seven months from March to October last year), whether the authorities have compiled statistics on the quantity of fresh water wasted in the past five years due to bursts of underground fresh water mains; if so, of the details; if not, the reasons for that?
The Government promulgated the Total Water Management Strategy in 2008 to address the challenges brought by climate changes. The strategy advocates containing the growth of water demand by promoting water conservation and effective water mains leakage management. It also seeks to create a new water supply framework by developing new water resources that are not susceptible to climate changes. The new framework comprises the primary water sources of local rainfall, Dongjiang water and seawater for flushing as well as various ancillary water sources, including desalination, reclaimed water, grey water reuse and rainwater harvesting. In this connection, the Water Supplies Department (WSD) commenced a consultancy study at the end of 2014 to evaluate the effectiveness of the current measures and project the long-term supply and demand of water up to 2040, with a view to making appropriate adjustments and enhancements to the current measures and formulating new policies and plans for water resources management.
My reply to the six parts of the Hon Lau Kwok-fan's question is as follows:
(1) As the data on quantity of fresh water used for toilet flushing for the whole year of 2016 is not yet available, we can only provide the quantity of fresh water used for toilet flushing in the territory for the most recent year, i.e. 2015, which is about 77 million cubic metres (mcm). Up to March 2017, there are about 35 500 customer accounts using fresh water for flushing in the territory. We do not have the associated data on the household number and population nor statistics on the quantity of fresh water used for toilet flushing by District Council district. We are therefore unable to provide this information.
Nowadays, the urban areas and most of the new towns in Hong Kong, covering around 85 per cent of the total population in the territory, are provided with seawater for toilet flushing. At the end of 2016, all consumers in Tin Shui Wai had switched to seawater flushing, which translates into an annual saving of about 10 mcm of fresh water. In the meantime, we are actively arranging for the residents of the Yuen Long area to switch to seawater flushing to further reduce the annual quantity of fresh water used for toilet flushing. At present, the major remaining areas that still use fresh water for flushing are the Peak, Southern District, Sai Kung, outlying islands and North District. In particular, the North District will switch to using reclaimed water for flushing in future.
The average production cost of fresh water, as calculated at the price level of 2015-16, is around $8.7 per cubic metre.
(2) As regards the plan to supply reclaimed water produced by further processing the tertiary treated effluent of Shek Wu Hui Sewage Treatment Works, we will take forward the infrastructure works for supplying reclaimed water to Sheung Shui and Fanling for non-potable purposes in stages. The infrastructure works for the relevant service reservoir and trunk water mains commenced in April this year. The design and preparatory works for the construction of the remaining infrastructure projects (including chlorination facilities, a pumping system and distribution mains) are also underway. Currently, we are developing an appropriate financial and legal framework for the supply of reclaimed water in Hong Kong. According to our initial estimate, the comprehensive use of reclaimed water for non-potable purposes in Sheung Shui, Fanling and the North East New Territories New Development Areas will translate into a saving of around 21 mcm of fresh water each year. We will continue to review the situation and, subject to technical feasibility and cost-effectiveness, extend the reclaimed water supply system to the areas not yet served with seawater supply so as to further reduce the use of fresh water for toilet flushing.
The production cost of reclaimed water varies with the treatment levels of sewage treatment works and the water quality of effluent. On top of the cost for sewage treatment, the additional production cost of reclaimed water to be supplied to Sheung Shui and Fanling is estimated to be around $5 to $6 per cubic metre at the 2015-16 price level.
(3) The fresh water output of the proposed first stage of the Tseung Kwan O desalination plant may reach 135 000 cubic metres per day or 50 mcm per year. Its unit water production cost (including the costs of the capital, energy, treatment, distribution and customer service) is estimated to be about $12 to $13 per cubic metre at the 2016 price level.
(4) To conserve precious fresh water resources, we have been advocating the adoption of grey water reuse systems or rainwater harvesting systems for non-potable uses, such as toilet flushing and irrigation, in new government works projects. As at the end of 2016, the Architectural Services Department and Drainage Services Department (DSD) have installed grey water reuse systems or rainwater harvesting systems at schools and government facilities in over 70 works projects in the territory.
Regarding private buildings, bonus credits are awarded to buildings with a grey water reuse system or rainwater harvesting system under the Building Environmental Assessment Method (BEAM) Plus for Existing Buildings Version 2.0 launched in March 2016 to encourage developers to provide these facilities in lieu of using fresh water for non-potable uses. The WSD also supports the Hong Kong Green Building Council in conducting similar review on BEAM Plus for New Buildings. As the provision of grey water reuse systems or rainwater harvesting systems in the private sector is voluntary, we do not have information on the private development projects that have adopted these technologies and the distribution of such systems by districts in Hong Kong.
At present, we do not have any plan to use recycled water from grey water reuse systems or rainwater harvesting systems for potable uses.
(5) The overflow from impounding reservoirs has been put under effective control with the adoption of the "package deal lump sum" approach in the agreements for supply of Dongjiang water since 2006. The overflow from local impounding reservoirs was significantly reduced by some 71 per cent, from an annual average of 94 mcm between 1996 and 2005 to around 27 mcm in recent years (from 2006 to 2016).
When the Lai Chi Kok Transfer Scheme was formulated for reducing the flood risks in the West Kowloon region, we took advantage of the opportunity it presented to take forward the Inter-Reservoirs Transfer Scheme (IRTS) concurrently. Under the IRTS, a tunnel connecting the Kowloon Byewash Reservoir and the Lower Shing Mun Reservoir will be built to transfer the overflow from the Kowloon Group of Reservoirs to Lower Shing Mun Reservoir to achieve the dual objectives of reducing the run-off flowing into the Lai Chi Kok drainage system and converting the overflow into potable water resources. Currently, the DSD is reviewing the detailed design, method statements and related environmental impact assessments of the IRTS in order to enhance its cost-effectiveness and prepare the implementation schedule. The review is making satisfactory progress and the initial conclusions are positive. In line with the proposals of the review, the DSD is refining the detailed design and method statements of the IRTS.
(6) The WSD has substantially completed the Replacement and Rehabilitation Programme of Water Mains at the end of 2015. The number of water main burst cases per year decreased from about 2 500 in 2000 to 116 in 2016 while the water main leakage rate also dropped from the peak of over 25 per cent to 15.2 per cent in 2016. The WSD is progressively taking forward the establishment of the Water Intelligent Network (WIN) with the installation of monitoring and sensing equipment in the water distribution network and application of advanced technology to continuously monitor the general condition of the water distribution network. The WIN project will divide the water distribution network into some 2 000 discrete District Metering Areas (DMAs) of manageable size, with high-technology monitoring and sensing equipment installed in the distribution network of each DMA. The WSD is also working to provide an intelligent network management computer system to analyse the tremendous amount of data collected from the monitoring and sensing equipment to enable timely determination of the most effective network management measures and the associated priorities for the DMAs.
The quantity of fresh water discharged as a result of fresh water main bursts in the past five years averaged less than 0.01 per cent of the total annual supply quantity.
Ends/Wednesday, May 10, 2017
Issued at HKT 12:05