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Advisory Council on the Environment

Ways to Reduce Water Consumption

(ACE Paper 4/99)
for information

1. Introduction
1.1 One of the Mission Statements of the Water Supplies Department is 'To remain conscious of our responsibilities towards the environment'. We share a common belief that economic development should not be at the expense of a deteriorating environment.
1.2

Promoting conservation is one of our key concerns. We are fully conscious of our responsibilities towards encouraging saving of water, especially fresh water. In this connection, we have been making continuous efforts to-

(a) create an environment of saving water;
(b) upgrade waterworks installations to use water efficiently and prevent wasteful use of water; and
(c) use of sea water for flushing as a replacement for fresh water.
 
2. Creating an Environment of Saving Water
2.1 Education
2.1.1 We have co-operated with various organizations, schools, environmental groups and the mass media to promote saving water and participated in events organised by them such as the annual United Nations World Water Day and the Environmental Funfair 1998 by the Friends of the Earth. As had been practised in the past, the publicity on saving water will be intensified whenever suitable circumstances arise.
2.1.2 We publish regularly posters and stickers to promote the message of saving water. The posters and stickers are distributed to the public through various channels such as giving them to hotels and management offices of housing estates.
2.1.3 Through joint efforts of this Department and Education Department, a firm message of saving water has been included in the syllabus of General Studies for Primary Three students. We provide positive support to the Education Department as well as publishers in their preparation of the related educational programs and publication of text books.
2.1.4 In 1999, we will upgrade our action by launching exhibitions in schools and housing estates and conduct seminars for the management personnels of housing estates to spread useful knowledge of water supply. Saving water will be a major part of the contents of these programs.
2.1.5 Visits to water treatment plants by school children and general public have been quite popular in recent years. This helps them to understand how potable water is produced and to inspire conservation.
2.1.6

Water saving slogan is printed on water bills to customers to remind them to save water.
 

2.2

Legislation

2.2.1

Our Department is the authority enforcing the Waterworks Ordinance. We make every effort to minimize waste of water through the enforcement of the Waterworks Regulations, notably the following-

(a) All plumbing design for buildings must be approved by the Water Authority prior to installation.

(b) The standard of design and materials used in plumbing of buildings are under our stringent control and we require the employment of licensed plumbers for the installation of plumbing works.

(c) Except with the permission in writing of the Water Authority, water supply shall not be used for any heating, cooling or humidification purposes.

(d) Self-closing taps must be used for the public or communal lavatory basins to prevent taps being left open.

(e) Wasting water or polluting water is an offence under the Ordinance.

2.2.2 Before 1996, the minimum flushing volume of toilets is 9 litres. With the relaxation of the Waterworks Regulations, 7.5 litres flushing cistern is allowed to be used in the flushing system to help reduce sewage production.
2.2.3 The introduction of dual-flush flushing cisterns to Hong Kong has been considered but has been ruled out. According to the Waterworks Regulations, all flushing cisterns should be of the valveless syphonic type. The valveless syphonic design is to ensure that there is a positive break to prevent waste of water which continuously flows into the bowl when the cistern malfunctions. Although dual-flush flushing cisterns may seem to use less flushing water, they are of the valve type and are not as effective in the prevention of waste as the valveless syphonic cisterns. Our experience shows that water loss due to defective valve type flushing cisterns is not easily detected by the users. Should such defects which are common occur, the amount of waste which is continuous will be very much larger than the saving. The water wasted will also increase the amount of sewage to be treated.
2.2.4 In the Hong Kong situation, sea water is the main source of flushing water supply and valve type flushing cisterns are difficult to work with sea water especially with respect to water-tightness. As only minimal treatment is given to sea water before distribution to consumers, the formation of deposits at the valve seating may gradually take place and this will result in leakage of water via the valve.
2.2.5

Most overseas countries use fresh water for flushing and some of them allow the use of dual-flush flushing cisterns. However, this type of flushing cisterns is not suitable for use in Hong Kong because of the reasons given above.
 

2.3 Metering of Water Consumption and the Tiered System of Water Charge
2.3.1 In Hong Kong, individual metering is adopted to truly practise the 'Users Pay' principle. It should be noted that in many parts of the world consumers' water consumption is still not individually metered and water charges are included in the rates or some form of property tax. Metered supply gives good incentive for water conservation as the water user has to pay for the water he uses. In fact this proves to be effective in Hong Kong's situation. Significant reduction in consumption was achieved when the programme for conversion from communal metering to individual metering was introduced in the 1960s.
2.3.2 In parallel with individual metering we have also adopted a differential water tariff system. We have different tariff rates for domestic, trade, shipping and construction supplies. While our tariff system basically aims at cost recovery, for domestic supply which accounts for a large proportion of the total consumption we adopt a tiered tariff structure which discourages extravagant users and helps encourage conservation.
2.3.3

The tiered system for domestic supply enables us to be one of the cities with the lowest per capita consumption of fresh water (112 litres/capita/day) among other major Asian Pacific cities (on average 157 litres/capita/day).
 

2.4 Proactive Actions
2.4.1 We carry out regular inspections on consumers' plumbing system to check for waste of water by careless customers. Prosecution actions will be instigated when there are sufficient evidences to indicate waste of water.
2.4.2

Our computerized billing system is able to spot unusual consumption patterns of water consumers. For every irregular account the registered consumer will be warned of possible wastage and inspections will be made to the consumer premises to check for any irregularities. Follow-up actions or improvement measures will be enforced after the causes for high consumption have been identified.
 

3. Upgrading the Water Supply System
3.1 Asset Management
  We are responsible for operating and maintaining about 6,000 kilometres of water mains and hundreds of waterworks installations including reservoirs, treatment works and pumping stations. Besides routine maintenance of the equipment, we realize that there is a need to launch an asset management plan for our installations to upgrade their condition to prevent waste of water. Under the asset management plan, a water mains replacement or rehabilitation programme will be implemented. The first stage of the programme has been scheduled to start in 2000 by replacing or rehabilitating 350 kilometres of aged water mains for completion by 2006. Priority is given to the water mains in urban areas and those most susceptible to leakage and bursting. This target has been set as one of our objectives in the 1998 Policy Address.
3.2 Leak Detection
  No distribution system in the world is free from leakage. We face the problem positively and make continuous effort according to a planned programme to detect leaks using the latest technology so as to reduce the amount of the unaccounted-for water and prevent the leaks from developing into main bursts.
3.3 Pressure Management
  Owing to our terrain or characteristics of some supply areas, higher water supply pressure than necessary may sometimes be provided to our consumers. As high pressure will increase leakage, we are implementing pressure management strategy to our distribution system and aim at maintaining a suitable supply pressure throughout the distribution system.
3.4 New Technologies
 

To meet the rising expectations of the community towards water conservation, we are committed to promoting new technologies which will help us to achieve the best use of valuable water resources. Through the use of new pipe materials which are less prone to corrosion, we can reduce leakage. We are carrying out research studies in identifying new techniques in rehabilitation of aged water mains as well as more efficient water fittings and devices which will save water. Recently completed water treatment works are environmentally friendly as they have been designed for full recycling of process water thereby minimizing the quantities of effluent discharge and sludge disposal, and thus maximizing water production. This environmentally friendly design is the standard design for all future water treatment works.
 

  Using Sea Water for Flushing
 

We consider that fresh water is a precious but limited resource. To have the best use of the resource, we have introduced the use of sea water for flushing purpose in the 1950s. Hong Kong is probably the only city in the world that sea water has been used so extensively for flushing (All new towns and most of the urban area, or about 75% of the population, are now supplied with sea water for flushing purpose). The supply of sea water helps to reduce considerably the consumption of fresh water. Currently over 540,000m3 per day of sea water is supplied for flushing conserving an equal quantity of fresh water. While this is a great achievement in itself in conserving fresh water resources which are limited worldwide, if solely from the point of water recycling and reduction of sewage treatment and disposal, the use of sea water does not offer much benefit over the use of fresh water for flushing.
 

5. Conclusion
  In view of the limited water resources, it is our target to make the best use of water resources by slowing down the rate of demand growth through conservation. This will not only reduce both the capital and the operation costs of constructing and running new water supply systems, but also help to postpone the need to develop new water resources. Water conservation also brings about savings in the cost of sewage disposal and treatment.


Water Supplies Department
January 1999

 

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