Genesis Housing Association is considering the future of Alexandra Court in Southend, which could see it torn down and a new block built in its place with double the number of flats.
One woman spoke of her dismay after being told it was her "home for life."
Genesis has assured tenants they would be re-housed at the same rents if demolition was approved.
There are currently 262 flats in the block on Baxter Avenue.
Brenda Philips, who has lived in Alexandra Court for 34 years, told BBC Inside Out East she was worried about the plans.
"When we moved in here we were told this was our home for life, and suddenly it`s not our home for life," she said.
She said she was also concerned at being moved out of her home for about 18 months while the new homes are being built.
"They`ve suggested to some of the residents here that they might move in to bed and breakfast accommodation or hotels, or we could go to Colchester or Chelmsford," she added.
Another resident, Carole Fisher, said: "I really like this flat. I don`t think there`s much wrong with it. We have had new kitchens, we`ve had new gardens.
"We`ve had central heating put in and double glazing, and I`m by myself and it`s easy to keep clean, easy to heat. I love my flat."
Resident Jan Swinton added: "It`s very important for me to be here because my daughter is disabled and she lives about 10 minutes away, and this is the ideal site here for me."
Social Housing Deficit
The National Housing Federation is calling for more investment in housing for social rent and many associations have serious concerns about social housing.
Jeremy Stibbe, of Genesis, said: "It [social housing] needs public subsidy, it needs grant, and that`s not been available.
"In 2012 the government stopped funding social housing. No-one wanted it to happen, but that`s what the policy was at the time, so to deliver social homes was impossible," he said.
James Prestwich, head of policy at the National Housing Federation, said: "England desperately needs more homes for social rent so it was absurd when the government stopped all investment in this type of property in 2011, whilst simultaneously cutting overall investment in social housing by two thirds."
A BBC investigation has found over the last five years in England:
- More than 150,000 housing association homes were demolished, sold or converted to affordable rather than social rent
- Only about 46,000 homes built for social rent, so housing associations are getting rid of more socially rented homes than they are building
A spokesman for the Ministry of Housing, Communities and Local Government said the number of social homes was "increasing," with 357,000 affordable homes provided since 2010.
"Social housing is a priority for this government and we want to go further to deliver the homes the country needs faster," he said.
"That is why we will set out ambitious reform plans in our Social Housing Green Paper and we are also investing £9bn in affordable properties."
Jeremy Stibbe, director of assets and investment at Genesis, stressed that demolition was only one option and the association was also considering whether to just renew the kitchens, bathrooms, windows and heating.
He said the age of the homes made that "difficult to manage" and "expensive."
Mr. Stibbe said not everyone was opposed to the new development.
"There`s a small handful of people who are concerned because they don`t want anything to happen, and there`s a broad range of people who are saying they are keen to see a new home because their current home doesn`t meet their needs.
"We won`t go for a redevelopment option at Baxter Avenue if residents say they don`t think that`s right for them."
He said building work takes about two years typically.
"They [tenants] may have to move temporarily. I can`t guarantee anything as we haven`t done that piece of work yet," he said.
The story will be broadcast on Inside Out East, on BBC One at 19:30 GMT on Monday.