Promoting Interdepartmental
Cooperative Water Saving Project
Water Supplies Department, Housing Department

Exemplary Services@Gov
2011

Protecting water resources for the future

Growing populations increase the demand for water supply. In tackling this problem, the Housing Department (HD) and the Water Supplies Department (WSD) have designed and begun implementing a special inter-departmental water-saving program to promote water conservation. Thanks to the efforts of both departments, the twin tank system, rainwater harvesting system, along with other water-saving devices are helping preserve the city's water resources for the future.

The innovative twin tank design

The twin tank water supply system was inspired by the interruptions in water supply experienced by public housing residents during tank cleanings, said Mr Stephen Wong, Senior Building Services Engineer of the Housing Department. By adopting an "alternating operation" mode, the twin tank system allows one tank to run normally while the other is being cleaned, which avoids service interruptions and reduces water wastage due to over-storage by tenants during service interruptions.

Through the joint effort by the two departments, 15 newly-built public housing estates already have twin tank systems installed as of January 2011. The twin tank systems installed in these estates will conserve approximately 1,600 cubic meters of fresh water and 400 cubic meters of flushing water each year. The two departments will continue to proactively work towards wider use of the twin tank system in government premises and private buildings across Hong Kong.

Under the "Total Water Management" strategy, the two departments are also promoting the use of other water-saving devices. Mr Wong said that the trial use of water-saving devices in the Hong Kong Housing Authority Headquarter has already demonstrated a saving of about 5% of total annual water consumption of the building. More than 460 government buildings and schools in Hong Kong already installed with these devices would be able to conserve an estimated 20% of water every year, added Mr William Tam, Engineer of the Water Supplies Department.

Recycling rainwater

The two departments have also been proactively promoting the use of rainwater harvesting systems in both public and private construction projects. Choi Tak Shopping Centre and Yau Lai Shopping Centre have already installed the rainwater harvesting systems which is expected to reduce the amount of irrigation water by 30 to 50% annually.

Implementing these various water-saving initiatives has posed a series of challenges for both departments. Mr Tam said that flexibility in making appropriate arrangement to accord with the situation and time was the key to success, especially for promoting the use of twin tank system. For promoting the use of twin tank system, the two departments have worked closely together, conducted thorough consultations with Relevant trade groups and the public and worked out the technical solution, in which gate valves are used at the inlet pipe together with the installation of automatic pump tripping device to ensure safety.

In addition to using water-saving devices, better water usage habits are essential to improving conservation. Through education and publicity programmes, the two departments hope to foster sustainable water-saving habits across the Hong Kong community.

Driven by a dedication to service, the HD and the WSD have managed to overcome obstacles and deliver a high-quality service to the public that will help preserve water resources for generations to come.

The two departments work closely together to help preserve the city's water resources for a sustainable future.
The two departments work closely together to help preserve the city's water resources for a sustainable future.
The two departments work proactively to promote a wider use of the twin tank system.
The two departments work proactively to promote a wider use of the twin tank system.
The concept of the twin tank water supply system originates from the two departments' determination to provide better services to the community and taking the lead in water conservation.
The concept of the twin tank water supply system originates from the two departments' determination to provide better services to the community and taking the lead in water conservation.
As of January 2011, 15 newly-built public estates already have twin tank systems installed.
As of January 2011, 15 newly-built public estates already have twin tank systems installed.