Hundreds of residents across the city were affected by the incident, which was first reported on Saturday morning.
Engineers from Portsmouth Water have been working throughout the weekend to fix 20 pipes, cracked by the sudden temperature changes.
It left scores of homes either without running water or with a low-pressure supply.
Ian Limb, of Portsmouth Water, said: ‘The rapid increase in temperature, from minus eight to eight degrees, caused ground movements that fractured a number of pipes.
‘We have about 20 burst water mains in the area.
‘This is a large number of bursts. We had complaints from Southsea to Hilsea. The majority of pipes in Portsmouth are connected in some way or another.’
Engineers were deployed shortly after 8.30am on Saturday. They worked to reroute the water supply, restoring pressure to a majority of homes within three hours.