People living in the SY3 and SY5 areas of Shrewsbury were affected by interruptions to their water supply from around 6pm on Tuesday.
A number of properties in Bicton Heath, around eight according to Severn Trent, were without water entirely for more than a full day.
The situation prompted criticism from residents who said they had tried to alert the water firm to the problems but had not received a response or any bottled water.
The company has now said it will be looking at what went wrong.
A Severn Trent spokesperson said: "We cannot apologise enough to any customers affected by supply interruptions in the Shropshire area.
"We will be looking into exactly what happened for these customers to make sure it doesn’t happen again.
"We can confirm that water was delivered to vulnerable customers impacted by the no supply in the area, however we recognise that it should have been delivered far sooner.
"Once again, we are really sorry to those customers that have lost supply, we know just how frustrating this must have been, especially during such warm weather."
Meanwhile supply issues caused by air locks in Craven Arms have also been fixed.
Some people in the SY6, SY7 and SY10 areas were left without water on Thursday morning, Severn Trent said.
The majority had water flowing again by early in the afternoon but some were without running water until the early hours of Friday.
Severn Trent tankers will still out working to fix the issue on Friday afternoon, with the company warning that some people would experience reduced water pressure until the airlocks are fully cleared.