At least 610 people have died so far after the rains triggered flooding and landslides that tore through mountain villages and towns, in some cases burying families as they slept.
More than 13,500 people have been left homeless in what has become one of the country's worst natural disasters.
On the fifth day since the start of the flooding outside of Rio de Janeiro, many people are still begging officials for aid.
Loved ones have now taken it upon themselves to search for the dead and help out those in need.Construction worker, Sergio Joaquin de Jesus, 48 - whose wife's brother and sister are missing - was one of those donating blood and helping to dig for bodies.
He said: "Imagine human beings up there, with no food, no water, nowhere to sleep, in this weather.
"They're living like dogs. Where is the government? What are they still waiting for?
"The ones I've seen go up there and really make the effort are all people from here", he added.
The Brazilian military has said it is sending 11 helicopters and 500 personnel to help approximately 800 rescuers from fire departments and the state civil defence agency, which is struggling to reach certain areas in the rain.
The army and navy have also provided heavy digging machinery, ambulances and generators to help continue the rescue efforts at night.
Low-hanging rain clouds have so far prevented helicopters from flying.
Amauri Souza, 38, from Teresopolis where a number of survivors have gathered, said there is not enough aid.
"A few helicopters have reached isolated areas, but they're only taking down the wounded.
"The water is rotten, but people are forced to drink it. There is no food. I had meat in my house, but it's all gone bad", he added.
Officials say the death toll could rise once remote areas are reached.
Experts claim the government could have been better prepared.
Margareta Wahlstrom, the United Nations' assistant secretary-general for disaster risk reduction, said: "This kind of tragedy does not need to happen.
"The government should have had an early warning and an emergency escape system in place", she said.
Meanwhile, flooding in Austrailia has been described as the "worst natural disaster in the state's history".
In Sri Lanka one million people have also been affected by monsoon rains, according to their government.