More than 150 miles of ageing metal gas mains are to be replaced across north-east England.
Northern Gas Networks said modern plastic pipes would be installed in place of the existing ones, some of which are more than 50 years old.
The £28m programme of replacement works will take place across Northumberland, Tyneside, Wearside and Teesside during the next year.
Some new pipes will also be installed in North Cumbria.
Major schemes will be carried out in most of the main towns and cities across the region, said the firm.
Durham will receive £3.6m of investment, with £3.3m for Sunderland and £3m for Gateshead.
Basil Scarsella, chief executive officer of Northern Gas Networks, said: "We have a major investment programme to replace all metal mains that are within 30m of any property during the next 23 years.
"Many of those mains are more than 50 years old, so by replacing them with modern plastic pipes we can ensure the continued safety and reliability of the gas network for the 6.7 million people who live and work in our region and rely on us to keep the gas flowing."
The work would inevitably cause some disruption, Mr Scarsella added, but he said customers would be given advance warning and kept regularly up-to-date.