Dwr Cymru/Welsh Water says a damaged trunk water main at Cross Keys was repaired over night.
Customers in Abercarn, Cross Keys, Ynysddu and surrounding areas have been affected since the incident on Wednesday.
Dwr Cymru/Welsh Water says it's working to restore supplies to communities cut off by a water leak.
It's affecting households and businesses in Abercarn, Cross Keys, Ynysddu and surrounding areas.
The company says its engineers worked throughout the night to fix the problem. It says it's a large, very high pressure water main and a significant amount of water was lost through the damage.
It says it anticipates that water supplies should begin to return during the course of the day however some customers may experience intermittent supplies as work to repair the pipe continues.
It's apologising for the inconvenience.
Dwr Cymru Welsh Water has announced its half-year results.
The not-for-profit company says it's delivered £123 million of investment in the six months to September.
It has over 3 million customers across much of Wales, Herefordshire and parts of Deeside.
With a heat wave approaching and more and more of us looking to enjoy the outdoors, Dwr Cymru Welsh Water is reminding people of the dangers of swimming in reservoirs and open water.
Welsh Water owns and maintains more than 80 reservoirs across Wales and although visitors are welcomed to these recreational sites, they should not swim in the reservoirs as it is extremely dangerous and can prove fatal.
It says the tragic deaths of two people at reservoirs in Brecon Beacons reservoirs (Ponsticill and Cantref) over the same weekend in 2013 are a reminder of the dangers presented by swimming in reservoirs.
- Automatic equipment located under the surface of the water, which can sometimes operate without obvious warning
- Very cold and deep water that can cause even strong swimmers to find themselves in difficulty
- Most reservoirs are in remote locations, with little or no mobile phone reception, so the chance of rescue is greatly reduced
Dwr Cymru Welsh Water has confirmed that it has agreed a £230 million loan facility with the European Investment Bank.
It says it will help it implement its £1.5 billion capital investment programme in the five years from April.
The not-for-profit company provides services to over three million people across much of Wales, Herefordshire and Deeside.
50 jobs have been created as Dwr Cymru Welsh Water's new water testing facility opened today in Newport.
The £10m facility will process 750,000 samples of water in Wales every year.
Dwr Cymru Welsh Water's new £10.4m water testing laboratory in Newport will be officially opened today.
The company says the facility, at Tredegar Park, employs 50 staff and will perform microbiological and chemical tests on samples of drinking water.
Dwr Cymru Welsh Water's Director of Waste Water says that most of the 2,000 blockages they deal with every month are caused by "everyday items put down the toilet such as wipes, sanitary towels, cotton buds and dental floss as well as fat, oil and grease that people have put down their drains."
Steve Wilson says many people aren’t aware that it is "illegal to throw or empty anything into our network that’s likely to damage a sewer or drain or to interfere with its free flow."
Dwr Cymru Welsh Water is urging people to stop flushing solid waste down sinks and drains as part of a new 12 month campaign to reduce sewer blockages.
The company says they deal with 28,000 blockages a year cost them around £7million.
The 'Let’s Stop the Block' campaign will aim to "change customer behaviour when it comes to putting things down the toilet and disposing of fat, oils and grease."
The programme includes visits to schools, shops and restaurants.
Welsh Water say they will target 'black spots' including Rhondda Cynon Taff, Caerphilly and the south Wales coast.
Dwr Cymru Welsh Water customers will see their average annual household bill rise by £7 from April.
It means it will increase to £434, which bosses say is the lowest average rise in Wales and England.
The company has more than a million customers.