BBC: Brazilian Environment Minister Izabella Teixeira has said the country's three most populous states are experiencing their worst drought since 1930.
The states of Sao Paulo, Rio de Janeiro and Minas Gerais must save water, she said after an emergency meeting in the capital Brasilia.
Ms Teixeira described the water crisis as "delicate" and "worrying".
Industry and agriculture are expected to be affected, further damaging Brazil's troubled economy.
The drought is also having an impact on...