The government has been urged to abandon the idea of increasing charges for water, with a community campaigner warning that some people can't afford to pay any more.

Officials note that Hong Kong's water charges haven't gone up for almost three decades and are much cheaper than in other advanced cities. They say any increases – to help plug a budget deficit – would be gradual and mild.

But Sze Lai-shan from the Society for Community Organization told RTHK on Tuesday that low-income households would struggle to cover higher water bills.

She said the authorities should consider waiving water charges altogether for people living in sub-divided flats, or provide them with a subsidy.

DAB lawmaker Edward Leung, a member of Legco's development panel, said the Water Supplies Department should consider implementing cost-cutting measures before increasing charges.

"There are some new technologies, equipment, and materials. They can also simplify work procedures and outsource some tasks. Implementing these measures can reduce costs," he said

"Right now they're running out of money, and need more income. Shouldn't they explore these options before they do what some people have described as 'pulling a knife on them?' Wouldn't this approach result in greater acceptance from the public?"