Why do people living in Sao Paulo use brooms instead?

Landlords in Sao Paulo have taken to using brooms instead. Sao Paulo state, home to one-fifth of Brazil’s population and one-third of its economic activity, is suffering the worst drought since records began in 1930. Pitiful rainfall and high rates of evaporation in scorching heat have caused the volume of water stored in the Cantareira system of reservoirs, which supplies 10 million people, to dip below 12% of capacity. This time last year, at the end of what is nominally the wet season, it stood at 64%. On April 21st the governor, Geraldo Alckmin, warned that from May consumers will be fined for increasing their water use. Those who cut consumption are already rewarded with discounts on their bills. The city will tap three basins supplying other parts of the state, but since these reservoirs have also been hit by drought and supply hydropower plants, fears of blackouts are rising.
   Without a downpour, Cantareira’s levels sink beneath the pipes which link reservoirs to consumers a week after Sao Paulo hosts the opening game of the football World Cup on June 12th. To tide the city over until rains resume in November, it is installing kit to pump half of the 400 billion litres of reserves beneath the pipes, which is called " dead volume". Mr. Alckmin has not ruled out tightening the spigots. Widespread cuts could hurt the governor’s reelection bid in October. Hours after he announced the latest measures, a thirsty mob set fire to a bus. The problem exposed by the drought is that supply has not kept pace with the rising urban population.