151.This section adds a new section 37AA to the WIA which provides that the Secretary of State may give directions to water undertakers about the basis on which a water resources management plan is to be prepared. The direction can only be given with a view to securing the ability of the water undertaker to meet the need for the supply of water to consumers. The direction can require that a plan be prepared on the basis of certain assumptions around resilience and security of supplies in drought and may be related to the risk of certain weather events arising, the frequency of customer restrictions or other bases for describing resilience, such as water security margins. The provision applies to the Secretary of State in respect of water undertakers whose areas are wholly or mainly in England.