Hundreds of residents in Canning Town have been forced to evacuate their flats following a water leak.
Homes and businesses in Hallsville Quarter were left without power after a burst pipe flooded a basement on Tuesday.
According to Thames Water, concrete was found close to a sewage line which, along with adverse weather conditions, caused water to back up at a nearby drainage system.
The blockage then caused a failure in the drainage system at Hallsville Quarter while the water damage has since caused a power outage, meaning residents were told to find accommodation elsewhere.
A Thames Water spokesperson said: “We were made aware of internal flooding at a business property in the Hallsville Quarter of Canning Town and our engineers have helped investigate the cause.
“We have found concrete in the nearby sewer line, which was suspected to have been caused by a third party and we investigated this to confirm the concrete’s origin.
“In the meantime, we set up tankers to pump away water and to prevent any further damage to the affected property. We are repairing the pipe, which was damaged by the third party, to help get things back to normal as quickly as possible.”
On Thursday, it was announced that FirstPort would book hotel rooms for residents from 29 October to 1 November, once requested.
According to FirstPort, insurers will reimburse hotel room fees at a later date, but the BBC reports that residents have complained about soaring bills and a lack of communication for when residents will be reimbursed.
Plamena Solakova, who rents a flat in the complex, said the situation has been “incredibly unsettling and upsetting”.
"No-one helped us to find hotels, we had to book at the last minute at huge cost," she said.
"We’ve spent over £600 in the last 72 hours on hotel and food bills. We have absolutely no idea when we’ll be getting this money back, what the process will be.
"It’s absolutely unreasonable in our view that we’re being asked to handle this situation on our own."
Newham Council is allowing those affected to charge electrical items, rest and use public facilities in an area at Trinity Community Centre.
The council has also organised for a cleaning contractor to be on site on Monday to remove any discarded food from freezers or fridges.
A spokesperson for the council said it was "supporting residents by assisting the management company", and fire wardens and security guards would "continue patrols in the affected blocks".
"We will continue to monitor the situation closely and stand ready to assist if required," they added.
A spokesperson for FirstPort said: "The safety of our residents at Hallsville Quarter is our absolute priority.
"As the development has been without power and water following the flooding, we have worked with the local council to evacuate most residents to alternative accommodation.
"We have had colleagues on site throughout to support residents and we’re working at pace to get them back into their homes as soon as it is safe to do."
FirstPort has been contacted for further comment.