“When you brush your teeth it’s awful, you can taste salt water, it’s disgusting!” says Isabel Moreira, 73, having to resort to bottled water to prepare mate – a herbal Uruguayan infusion – at her home in Montevideo. Uruguayan authorities are mixing salty water from the Rio de la Plata river estuary with its dwindling freshwater supplies to meet demand, as the country struggles with a historic drought that has left its main reservoir dry.