The state of Norwich's drains has come under the spotlight after concerns that many gullies are blocked and causing flooding.

But council leaders, who admitted just one vehicle is responsible for clearing all the gullies, defended the measures taken to clean them and said they would all be cleared over the course of the year. The issue was raised at a Norwich City Council meeting by David Fairbairn, Liberal Democrat councillor for Lakenham, and by Richard Edwards, Green county councillor for Mile Cross.

Mr Edwards said he knew of a drain on the cycleway and footpath leading from Soleme Road to Drayton Road that had been blocked for three years. And Mr Fairbairn said: 'In my opinion, about half of all the gullies in Norwich are full up with earth and detritus, and are consequently unable to carry away the water in the the gutters when it rains.'

He asked: 'How many gully cleaning vehicles does the contractor have in operation in Norwich and how many men are involved full-time at this function?'

Victoria MacDonald, cabinet member for environment, said there was one gully cleaning vehicle in Norwich, as there had been under the previous contractor, with two full-time staff.

She said May Gurney – which had been carrying out gully cleaning since last April – was performing well. She added: 'It costs more than 20 times as much to respond to individual reports as it does to carry out gully cleaning on a planned basis.

'A reactive approach service is simply not affordable on widespread scale. However, gullies will be cleaned on an individual basis if there is an immediate risk to safety or property.'

Mrs MacDonald added that of the 11,268 gullies cleaned to date, 3,446 had to be cleared by digging instead of the usual suction method. She said: 'This has slowed progress, but even so, all the road gullies are planned to be cleared this year. Not only are some gullies full of silt, but they can also have debris such as needles, slabs, bottles, car batteries, pieces of wood or metal.'

Mr Fairbairn asked if she could investigate the possibility of getting in an extra cleaning vehicle. Mrs MacDonald said she would look into it, but that it might be difficult at a time when there was pressure on the budget.