Lamma Island's primitive septic tanks will soon be flushed away by a modern centralised sewage system the government says will improve hygiene and the marine ecology.
The HK$420 million Drainage Services Department project is expected to benefit 5,000 island residents. Construction started in 2010 and the first stage of the system is expected to come into use next year.
The island is one of the few places in Hong Kong without a public sewage system. Instead, waste for the 2,000 to 3,000 homes is processed through 1,000 buried septic tanks. Sewage is filtered through the soil and ultimately flows out to the sea.
Some of the tanks, which have operated since the 1930s, no longer function effectively due to a lack of adequate maintenance. Sewage from other homes is pumped directly into the sea.
The project involves a pipe system that will pump waste from toilets to treatment plants at Yung Shue Wan and Sok Kwu Wan. But households will have to spend more than a penny to take advantage of it - the cost of connecting to the network will be between HK$10,000 and HK$30,000.
The waste will still be pumped into the sea, but only after 90 per cent of impurities have been removed.
'The water will be at least 10 times better when it reaches the sea,' said Henry Chau Kwok-ming, an engineer with the department. 'The project will provide a better environment for [marine life] and improve the island's hygiene.'
The installation of undersea pipes did not require removing any soil, said Oliver Au Yeung Wai-keung, of the contractor Scott Wilson, so the marine ecosystem suffered minimal damage. Coral reefs and fish would not be affected, Au said.
A remote-controlled helicopter with a camera and video recorder is being used to help monitor the work.
The percentage of homes and businesses that still manage their own sewage treatment, most in remote areas of the New Territories