That prediction emerged from Scottish Water on the eve of a fact-finding tour last weekend by senior local authority flooding and infrastructure experts.
In an email to flood-threatened residents, Bill Elliot, stakeholder development manager at the utility, revealed that a draft technical report was being studied by the flood team and senior management.
The proposed solution for the Charles Street, Greenlea Road and Rose Street area, he explained, would be very expensive and further research and sewer modelling work remained to be completed.
In his message, Mr Elliot stressed that they were working closely with Dumfries and Galloway Council.
He said: “It is hoped that a decision should be made within eight weeks and sooner if possible.
“It is important to note that any work that is agreed would be a large undertaking and take significant time to plan and deliver on the ground.”
Mr Elliot added that it was important that they delivered interim protection measures to those properties at risk of sewer flooding.
On Sunday morning, council officials Brian Templeton, team leader (flood risk management) and James McLeod, service manager (infrastructure), joined local councillor Richard Brodie on a tour of hillside areas of the town with a history of flooding.
The latest damage followed an extreme tropical-style prolonged rain downpour on Saturday July 22.
As well as meeting residents in the streets adjoining flood-hit Newington Park, the officials also learned first hand about problems in the Millview Terrace, Springbells and Prestonfield Road areas.
Concerns were also expressed about the impact on the cost of house insurance in the neighbourhoods.
Describing the exercise as very worthwhile, Councillor Brodie, who organised the tour, concluded that the officials were left with ‘a clearer picture.’
He said: “Hopefully local people will see that the council is interested in the problems which they are experiencing, even though we don’t have pots of money to address them.
“The council will be meeting again with Scottish Water which has overall responsibility for ensuring that the infrastructure can cope with the situation we had in July.”
Lorry driver Stuart Kirkpatrick, who lives with his wife Carol in Greenlea Road, prevented floodwater and sewage entering their’s and neighbouring houses by knocking two holes in his garden wall with the help of a friend and released it onto the adjoining street.
He welcomed Sunday’s council consultation but said he would not be reassured until he saw a firm commitment to invest in infrastructure improvements.
Mr Kirkpatrick said: “For the last decade or so there seems to have been a four-year cycle between the drains and sewers overflowing down the hill through Newington Park.
“These incidents are followed by discussion about improvements but after all this time nothing appears to have resolved the issue properly.”
But Mr Kirkpatrick cautioned: “We’re not any further forward yet. It all depends on funding being allocated.”
A Dumfries and Galloway Council spokeswoman stated that the tour was aimed at providing a better understanding of the issues.
She said: “We have shared our findings with Scottish Water who we will be meeting mid-November to discuss what options may be viable to alleviate any future flooding problems.”
Meanwhile, Scottish Water confirmed they were undertaking further network investigations to help residents of Charles Street, Rose Street and Greenlea Road.
A spokesman said: “This will then inform the recommendations we can take forward together with Dumfries and Galloway Council for short term and long term solutions.”