The restriction is to allow water levels to recover following a mechanical failure.
Overnight water restrictions will be in place in Westmeath tonight.
Irish Water customers in Athlone and surrounding areas will be affected by the stoppage between 10 o'clock tonight and 6 o'clock tomorrow morning.
Westmeath County Council and Irish Water say the restriction is necesesary to allow water levels in the Annagh Reservoir to recover following a mechanical failure.
Supply is expected to be restored between 6 and 8 o'oclock tomorrow morning as the water returns to the network.