Emergency water supplies will be delivered to elderly people at three sheltered housing developments in east Belfast on Thursday.
Alliance MLA Anna Lo has arranged for tankers to deliver water to Benmore Court, Malton Fold and Elgin Court.
The residents are among those struggling in water shortages which have left about 36,000 people across Northern Ireland without water.
Ms Lo said the crisis had been badly handled by NI Water.
"This situation is completely unacceptable. There should have been more preparation for the loss of water but NI Water does not seem to have put many resources in place to deal with these problems. Their response has been completely useless," she said.
"They have tried to make water available from certain locations, but you have to queue for a long time to receive a small amount and you have to be able to transport heavy bottles of water."
The MLA said vulnerable people have not been taken into account.
"That is why I have organised for this delivery of water to these three sheltered housing developments. Elderly residents and those with a disability have not been given any support by the authorities which is a disgraceful situation.
"I have however seen the actions of good Samaritans who have been helping their neighbours during this chaos."
Tony Giffen, head of housing operations at Oaklee Housing Association, the company which runs Benmore Court, said the delivery would help a great deal.
The complex, which houses around 30 mainly elderly people, has had no water since early on Wednesday.
Mr Giffen said the company has had to beg, borrow or steal water from various outlets in order to accomodate its residents.