Green groups have criticised police for wasting at least 200 tonnes of water to fill the plastic barriers used during the three-day visit of President Hu Jintao last weekend.
About 200 of the two-metre-high barriers, each one weighing two tonnes when filled with water, were placed around the Convention and Exhibition Centre and Grand Hyatt hotel in Wan Chai as part of security for Hu's visit.
About one tonne of fresh water was needed to fill each barrier and afterwards they were emptied at the scene before being removed because they were too heavy to move when full.
Green Power chief executive Man Chi-sum said the total amount of water poured away could have supplied more than 900 adults, or about 300 families, with water for one day.
'Of course it is wastage,' he said.
'There is a shortage of water in Hong Kong and the whole world. Less than 1 per cent of the world's water resources is drinkable.'
Man said the police should have used processed sewage to fill the water barriers, or recycled the water for cleaning or watering plants.