HOUSEHOLDS will soon face two extra costs, with charges for dumping refuse being considered at the same time as the Government works on plans to introduce rates for sewage disposal. The plan for a charge on household waste was announced in yesterday's budget estimates and comes only a few weeks before the sewage disposal charges will be unveiled. Both plans are expected to be controversial, but a waste disposal charge could be the most problematic because of the difficulties in assessing it. Sewage charges likely will be linked to water consumption, for which a billing system is already in place, but it would be a logistical nightmare for the Government to measure waste output from each household and business. The municipal waste charge proposal also comes as the Government appears to be backpedalling on plans to charge for construction waste, which it said last summer would be introduced during the coming financial year. The Assistant Secretary for Planning, Environment and Lands, Mr Nicholas Fry, said the charging scheme recently had been agreed in principle by a working group involving his branch, the Finance Branch, the Economic Services Branch and others. Details needed to be sorted out and could be complicated because several branches of government were involved, including the municipal councils which collect the waste, he said. The councils charge a general rate which covers collection but it was unclear what portion of the rates this constituted and whether it would be part of a new charge, he said. Rates did not take into account the disposal fee, which currently is covered by other departments such as civil engineering, he said. The construction of three new landfills over the next few years, worth more than a total $7 billion, could also be a factor in the charges. Planning and environment expert, Dr Peter Hills of Hongkong University, expected it would be difficult to determine waste charges for individual households or companies, given most were located in multi-storey buildings. ''It's relatively easy with sewage charges because they can be calculated according to water consumption,'' he said. ''But when you're dealing with centralised collection facilities within residential buildings, it would seem much more difficult to relate the charges to anything.'' Legislator the Reverend Fung Chi-wood, who is the United Democrats spokesman on the environment, said he was concerned the household charges were being mooted while those for construction waste, which makes up two-thirds of the waste arriving at landfills, were on hold. Mr Fung said household fees would hit the public hardest, much the same as the sewage charges would. But Mr Fry said waste charges could be beneficial by minimising the waste produced and getting people to think about alternatives to products that generate a lot of waste. Friends of the Earth spokesman, Mr Henry Morritt, agreed it was commendable to use charges to reduce waste, but warned it would be difficult to fulfil without measuring every household's rubbish first.