Around 3,500 homes and businesses in Bury St Edmunds are currently without water due to a burst water main.
Residents in the north and eastern parts of the town reported being without water or having a reduced pressure shortly before 7pm, with villages as far north as Ampton and Culfordheath also said to be affected.
The issue has been caused by a burst water main near the A14.
A notice from Anglian Water says: "We're really sorry but some customers in Bury St Edmunds may have very low water pressure or no water at all.
"We've Identified a burst water main in your area that we're working hard to get fixed, so that we can get your supply back to normal as soon as possible.
"Again, we're really sorry we've inconvenienced you and thanks for your patience."
One Bury St Edmunds resident said: "I spotted the water was off when I was getting my children ready for bed.
"After a quick look on social media, it seems lots of people in Bury St Edmunds have been affected.
"Hopefully it wont take long to get it back on."
An Anglian Water spokeswoman confirmed teams are working on resolving the issue, having isolated the root of the problem.
Homes reported their supply returning around 8.40pm, and Anglian Water aim to have water fully restored by 11pm.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here