Communities face six weeks of chaos as a section of the coast road closes.
The closure is part of a £250,000 water mains scheme in Portesham.
Residents fear the closure will cause chaos on the roads and raised concerns about the effects on the village.
Teams will work on a 200-metre stretch of the B3157 (Goose Hill) to the west of the village, replacing the main with new plastic pipes in a project that will start on Monday, September 30, and will continue for six weeks, with a scheduled finish on Friday, November 8.
The road will be closed to through traffic in both directions between the entrance to Manor Dairy and just past Malthouse Meadow for the main replacement, with work continuing seven days a week to get the project finished as quickly as possible and the road reopened.
Traffic will be officially diverted using the B3157, A354 (Weymouth Way), B3159 and A35 roads and, as well as traditional road signs, digital road displays will be in place at various locations, including Weymouth and Bridport, to advise drivers about the closure.
Lee Worsley, owner of The Kings Arms in Portesham was concerned that the road closure could severely affect his business.
He said: "The effect on business I would have thought will be quite catastrophic.
"I think people will just not come along the coast road.
"I think there should be some compensation for businesses, we don't know what staff we will need and it is not a short closure.
"We are talking potentially tens of thousands of pounds.
"We still have bills to pay and staff to pay in that time.
"They say it is an emergency but if they had chosen November or January, the effect would have been considerably less on us."
The closure to Goose Hill is also likely to cause traffic to use Front Street as a rat-run for vehicles travelling between the Coast Road and Dorchester or Bridport.
Residents on Front Street raised concern about the likelihood of increased traffic through their road.
Nikki Carr said: "The traffic through the village is ridiculous as it is.
"It is noisy, it's constant and it is used as a race track.
"It is used as a rat run and vehicles that are far too big come through here, it is like living in a town.
"When they close the road it is just going to be carnage."
Peter Manning, 72, added: "I hope it brings less people through the village and makes the road quiet.
"This is used as a cut-through, anything that interrupts that traffic is fine by me.
"Far too many large vehicles use this road as a shortcut as it is.
"It is ridiculous on this B-road, it should be a 20mph limit and a seven-ton limit."
Lead design engineer Daniel Owen-Rijnenberg said: “This is an important project because customers have suffered inconvenience and disruption to their supplies on a number of occasions in recent years due to the existing main bursting.
“The new plastic pipes will help to ensure that improved water quality and a more reliable supply is in place for future years.’’
He added: “Road closures are always a last resort and we’ll be working hard seven days a week to complete this project as quickly as possible because we recognise the B3157 is an important route locally.
“We’re teaming up with Dorset Council to ensure traffic can be safely diverted and that road users are aware of the diversion in place and we are working closely with businesses in Portesham to try and reduce the impact of this work on them.
“We’ve also written to customers across the area to tell them about this project and are also working with local bus services to ensure that pupils can continue to travel to and from schools.’’
A public drop-in session about the project is being held at Portesham Village Hall, Malthouse Meadow (DT3 4NS) between 3-5pm on Wednesday, August 14, where Wessex Water team members will be available to discuss the project and answer any questions from customers.
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