THE Government is asking people to pay monthly charges for a new sewage system that could create pollution problems and may not be built in its entirety, Friends of the Earth claimed yesterday. The proposed sewage charges would see households paying up to $30 a month to have their waste water treated and piped via a 30-kilometre underwater tunnel into the South China Sea. Industry would pay a surcharge. The administration is consulting the public on the charges but not on the system itself even though there are outstanding questions about it, Friends of the Earth said. China has not agreed yet to the pipe, the sewage could cause pollution problems in the South China Sea, and part of the treatment process will produce huge quantities of lime sludge needing disposal in landfills which already are strapped for space, the group said. But the Environmental Protection Department (EPD) countered it was late in the day to be arguing about a system that has been in the works since 1989 and for which building contracts are about to be let. Assistant Director Mike Stokoe said they had pored over more than 1,000 options before deciding on the tunnel. ''If FoE thought there were flaws, they should have said so in 1989 when we publicised the strategy,'' he said. Friends of the Earth's campaign co-ordinator, Lisa Hopkinson, agreed their criticisms had come late in the day but this was the only opportunity to raise a formal objection. The sewage strategy is intended to clean up polluted Victoria Harbour. About $10 billion will go towards building the underwater tunnel and a treatment works on Stonecutters Island, for which a contract is about to be let. Another $14 billion will be spent on sewers connecting to the treatment plant. ''We're being asked to pay for something and we want to make double sure it's the best solution,'' she said. The EPD plan suggests partially-treated sewage discharged by the tunnel will be dispersed by sea currents so it does not create a pollution problem. But there were no contingency plans in case the tunnel plan did create pollution or was turned down by China, she said. Cities elsewhere were abandoning marine disposal because it washed back to shore or created other problems, she added. ''It just seems crazy that a first world economy is going with treatment technology that the rest of the world is moving away from,'' she said. Mr Stokoe said the strategy might not be perfect, but it already was rolling. Even if the tunnel could not be built, there would still be environmental benefits, he said. He was ''99.95 per cent'' sure the sewage would not create pollution problems based on environmental impact assessments, and he pointed out that Chinese authorities had not turned down the pipe even though they had not yet approved it.