Tens of thousands of homes could be without water until the weekend because of a technical issue at a Southern Water supply works.
Almost 60,000 homes across Hampshire - in Southampton, Romsey, Eastleigh, Totton, and parts of the New Forest - have low pressure or no water at all.
Southern Water said it is so sorry and said that problems at the Testwood water supply works are preventing water from leaving the site.
Long queues have been reported at the water bottle stations which have been set up.
The company said it is delivering water supplies to customers registered on its priority list, along with to Southampton General Hospital and Princess Anne Hospital.
It said this morning that its teams have fixed the problem and are filling up the reservoir - but it is a gradual process meaning homes may not have access to water until the weekend.
Yesterday the supplier said the problem is affecting a total of 10 postcodes – SO15, S016, SO40, SO42, SO43, SO45, SO50, SO51, SO52 and SO53.
It comes as households were warned about massive bill hikes averaging £31 a year - with Southern Water customers are being hit hardest with bills going up 53 per cent.
Pictured is one of the bottled water supply sites in Southampton
There are three bottled water stations - at Staplewood Football Development Centre in the Marchwood area of Southampton, Places Leisure Centre in Eastleigh on the edge of the city and at Asda in Totton.
This morning, Southern Water saidL: We continue to work hard to restore supplies to Southampton, Eastleigh, Romsey and the New Forest.
Overnight our teams have fixed the problem at the Testwood Water Supply Works and restarted the site.
Were now filling up the reservoir again with drinking water, ready to restore supply.
This is a gradual process which must be done carefully and safely, but customers will start to be reconnected later today.
We are so sorry for the disruption this has caused you. We are working towards all customers being back in supply by the weekend.
Hampshire County Council have listed 24 schools which are currently closed.
In Southampton, nine schools have been forced to remain closed today due to the water problems.
These are Upper Shirley High School, Shirley Warren LC Primary and Nursery School, Holllybrook Junior School, Hollybrook Infant School, Compass School, The Cedar School, Fairisle Infant and Nursery School, Sinclair Primary and Infant School and Fairisle Junior School.
The Southampton branch of the teaching union the NEU advised teachers that they should refuse to work if there is no running water.
Lots of residents say they are on the priority list but are yet to get any water
Southern Water said it is so sorry after thousands of people were left without water. Pictured is a supply tanker
Southern Water said the problem is affecting 10 postcodes: SO15, S016, SO40, SO42, SO43, SO45, SO50, SO51, SO52 and SO53
Last night, one of the bottled water sites ran out in the blink of an eye and locals had to resort to buying fizzy drinks, juice, and milk.
It comes as water bosses were today given the green light for huge bill hikes averaging 36 per cent over the next five years.
An eye-watering round of increases was announced by regulator Ofwat, despite fury at the performance of operators.
Southern Water customers are being hit hardest with bills going up 53 per cent over the period - and inflation projected to add another 10 per cent.
Thames Water, which has been paying bonuses to executives despite being in the grip of a funding crisis, has been allowed a 35 per cent increase.
The bill rises for England and Wales - averaging £31 a year - would begin to take effect from April next year.
The move comes at a time of public outrage over pollution in rivers, huge salaries paid to water company bosses and massive dividends taken by shareholders.
Jill Woolger, 66, lives in Dibden Purlieu - a village on the edge of the New Forest - and says she has been without water since Wednesday morning.
She only had around a litre of bottled water left to last her for the evening.
The retired nurse, who lives with an autoimmune condition, is registered on the firms priority list and was told she could expect bottled water to be delivered to her home by 7pm, but claims she did not receive any.
She said: I think what Im so fed up about is that Im on the priority service, but I havent had any water.
Ms Woolger lives with ulcerative colitis, which is an inflammatory bowel disease that can cause ulcers, and psoriatic arthritis, and said her autoimmune conditions can make her more prone to infections.
She added that having water to keep her house clean is vital to avoid impacting her bowel movements.
She claimed water issues in her area seemed to be a recurrent problem after being hit with outages three times in two years, and criticised Southern Water for not offering better support to customers on the priority list.
Pamela Bird, 81, and her husband Henry, 80, also live in Dibden Purlieu and have been without water since yesterday morning despite being on Southern Waters priority list.
Mrs Bird told the Daily Echo: Im disgusted with Southern Water, I think their response has been terrible.
You see in the news that OFWAT are putting up their bills yet ordinary people suffer.
Weve been without water since yesterday and are on Southern Waters priority list but we still havent heard a thing.
Weve tried calling but youre left with automated messages and then when we did get through to a human being we were told they werent the relevant department and couldnt help us.
We, like so many others are vulnerable in this kind of situation and I think its been dreadful from start to finish. Youve got to look after yourself because nobody else does.
Last night, mother-of-two Sian Phillips - from Hythe - and despite also being on Southern Waters priority list, was yet to receive any bottled water.
Her three-and-a-half week old baby needed medicated formula for a dairy milk allergy.
The mother was worried about not being able to sterilise his bottles if she doesnt receive water soon.
Councillor David Harrison said residents are angry about failures to set up bottled water stations and the spurious information provided by the company, claiming that they had set these up, when they had not.
It has caused a lot of wasted time spent in traffic queues, he added.
Eastleigh MP Liz Jarvis hit out at Southern Water for the outage, which has been ongoing for more than 24 hours.
The Liberal Democrat MP said: This is yet another mistake from Southern Water just as bills are expected to rise for consumers. Our area should not be subject to period water shortages – it is unacceptable.
Consumers should not have to pay to clean up Southern Waters mistakes, whether that is dumping sewage in our rivers or failure to provide supply.
I urge all constituents to check in on and inform vulnerable loved ones about access to emergency bottled water at Place Leisure Eastleigh, and I will be staying in touch with Southern Water as this situation progresses.