South West Water has extended the hosepipe ban to most of Devon to boost water supplies at Roadford reservoir, affecting around 390,000 homes.
The initial ban in Cornwall and a small part of north Devon remains in place since August 2022.
Using a hosepipe can lead to a fine of up to £1,000 for offenders.
David Harris, South West Water’s Drought and Resilience Director, said: “However, despite our interventions and investments, and the fantastic efforts of our customers, the region’s water resources are under immense and increasing pressure.
“Extending the hosepipe ban to parts of Devon is the responsible thing for us to do and going into the summer period is the right time to do it.”