Residents in both areas say they are either without water or have a very poor supply.
Severn Trent messaged customers and posted on its website to apologise.
It said: "We're aware that customers living in the SY11, SY12 areas of Ellesmere and the surrounding areas may be experiencing some supply interruptions at the moment.
"We’re really sorry if you’re experiencing these issues and want to reassure you, we’re working hard on getting this fixed as soon as possible.
"There is a team currently investigating the cause and we’ll update this page as soon as we have some more information to share.
"We apologise for any inconvenience this may cause."
The water was due to be back on by 6pm.