Pledges to save water were being sought from people in Ashford, Kent, on the day the first drought order came into force in the South East.
Three water companies have been granted drought orders
People were being urged to conserve water at a festival in the town, where major housing growth is planned.
Ashford's Future, which is overseeing expansion, said its board was tackling water supply issues ahead of building.
It coincided with Sutton and East Surrey Water's drought order being imposed in another part of the region.
This week, Southern and Mid Kent water companies were also granted drought orders.
Both water companies have said they will not use the orders yet.
Managing Director of Ashford's Future, Martin Bacon, said: "It is essential that the growth of Ashford is supported by reduced and less wasteful use of water in factories, schools, offices and in our homes.
"Ashford's Future Delivery Board has already identified Ashford as an area of low rainfall and potentially low water resources.
"In response the delivery board is working with key partners to address water supply and water treatment for both the existing town and for the areas of planned expansion."
Impact on wildlife
The Ashford Water Festival was organised by Kent County Council, the Environment Agency, Ashford Borough Council and Ashford's Future.
Activities included street entertainment, a competition to guess the volume of water an average person will use that day, and guided walks along the river.
Shoppers were urged to make pledges to conserve water at home, create drought-resistant gardens, and make every effort to use water butts.
It came as the region suffers its driest period for 70 or 80 years. Widespread impact on the environment and wildlife has been predicted.
Kent area manager for the Environment Agency, Harvey Bradshaw, said the region could be facing its worst drought for a century.