Severn Trent Water said supplies were assigned to four postcodes in Nottinghamshire – NG5, NG6, NG8 and NG20.
A reader from the NG5 area said he was without water for more than four hours on Sunday evening.
There are also customers around NG17 where the pressure can be low on Monday morning.
The water company said the system was filling up after equipment failure at its groundwater site on Sunday.
Nottingham hit sweltering highs of 29C / 30C over the weekend and will remain warm on Monday.
Bottled water has already been delivered to vulnerable customers and bottled water stations are now open at Tesco Express, Chesterfield Road Huthwaite NG17 2PY and the parking lot opposite, next to the market square.
In a statement, Severn Trent Water said Monday morning (July 19): “We cannot apologize enough to all those affected by the problems with the water supply reduction in Mansfield and the surrounding area, we know. how hard it is to be without water, especially in such hot weather.
“We are pleased to report that the issue, caused by equipment failure at one of our groundwater sites and exacerbated by the hot weather, has now been resolved and the site is back up and running. As the system recharges, we know there are a few customers who are experiencing low pressure, particularly in Huthwaite.
“To help the system fill up and water supplies return, we ask customers in the larger area who still have water to use it sparingly and to avoid things like watering the garden or the use of garden hoses. This way we can help each other and get things back to normal as soon as possible. Once again, we are incredibly sorry for the disruption this has caused and we would like to thank everyone for their continued patience, especially under very difficult circumstances. “
Councilor Jason Zadrozny, Chief of Ashfield District Council, said: “Many residents of the NG17 (Ashfield) area had water supply issues yesterday. This has created an extremely dangerous situation, especially for families and the elderly, and it is unacceptable.
“I have requested a meeting with Severn Trent to discuss the continued failure of our water supply and to obtain assurance that their issues will be resolved. “
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