Further restrictions on water use in Northern Ireland could be put in place if dry weather continues, according to the region's water supply company.
Sara Venning, the head of NI Water, said the reservoirs were 70% full.
But without rain in the near future extra measures on top of the existing hosepipe ban - imposed two weeks ago - might have to be considered, she added.
A close eye is being kept on Spelga Reservoir near Hilltown in County Down.
It helps to service 100,000 customers in places in the county like Newry, Kilkeel and Banbridge.
It is only half full, with its level dropping to the point that an old road that usually sits well below the waterline has been exposed.
Thousands of people have been visiting the reservoir to see it at its lowest level in recent years.
But Spelga Reservoir has been lower than its current level - in 1995 a prolonged summer drought left it at 30% of its capacity.
Ms Venning said that NI Water expected reservoir levels to drop in summer.
But she said the last two weeks had been without significant rainfall, coming on top of an already dry June.
Engineers are reducing the demand on Spelga and drawing on other sources to balance supply to that part of the network.
Ms Venning said she hoped that and the reduction in demand that has resulted from the hosepipe ban would be sufficient to address the supply issues.
In the Republic of Ireland night-time supply interruptions have been introduced to manage demand.
Asked whether such restrictions might be necessary at Spelga, Ms Venning said she hoped not, before adding: "It isn't something though that I would rule out."
The company has also defended itself after it emerged that recent hosepipe ban advertisements did not appear to accurately reflect the law used to impose it.
It was suggested that the company had listed activities banned under Great Britain regulations but not Northern Ireland ones.
The ban in Northern Ireland only applies to the use of hosepipes to water gardens, road vehicles or vehicles towed by a road vehicle.
Ms Venning said she believed the ban was "within the letter and spirit of the law here in Northern Ireland".
"The ban was brought in to effect behaviour change and we absolutely have seen that behaviour change and we don't believe we overstepped the mark," she said.