caption: MERTHYR TYDFIL, UNITED KINGDOM - MAY 29: An aerial view of low water levels in the Llwyn-on reservoir in Taf Fawr valley on May 29, 2020 in Merthyr Tydfil, United Kingdom. The Met Office have said May is on course to be the driest in 124 years with only 14.3mm of rain since the month began - 17% of what is normally expected. (Photo by Matthew Horwood/Getty Images)