PART of Eastern Road will be closed overnight tomorrow while engineers try to repair a sewer leak.
The southbound route, from the A27 junction to the junction with Anchorage Road, will be shut from 8.30pm on Thursday until 5.30am on Friday.
A team from Southern Water are hoping to examine and repair the leak during the closure.
In a statement the company said it had temporarily stopped the leak by shutting off part of the sewer and redirecting flows.
It said: ‘Our main concern is to carry out any repairs as quickly and safely as possible, while causing minimal impact to drivers and local residents.
‘In the meantime we are liaising with our colleagues in the Environment Agency and Portsmouth City Council.
‘We understand this may have an impact on road users and we would like to apologise in advance and thank people for their patience while we carry out these vital repairs.’
If the work cannot be completely safely overnight further repairs may have to be carried out next week.
The company have already applied for a further temporary road closure order from the city council, which would start on Tuesday, June 20, and last up to five days.