"When a policyholder contacts his/her insurer and verifies his/her identity, he/she can receive an advance payment for up to $5,000 on a flood claim, without an adjuster visit or additional documentation," FEMA said.
"Up to $20,000 may be advanced to a policyholder who provides photos and/or videos depicting damage and receipts validating out-of-pocket expenses related to flood loss, or a contractor's itemized estimate."
In addition, policyholders affected by Hurricane Harvey who have not been able to renew their policies will get a grace period of 120 days to do so, FEMA said.
It's part of the slow, arduous road to recovery as tens of thousands of people were uprooted from the historic hurricane and floods.
Also on Monday, residents were able to return to the 1.5-mile evacuation zone near the Arkema chemical plant in Crosby, Texas. Organic peroxide overheated and ignited, causing multiple fires at the flooded chemical plant near Houston
Officials let chemical containers catch fire and burn out rather than endanger firefighters, the EPA and the Texas Commission on Environmental Quality said in a joint statement.
People living within 1.5 miles of the Arkema site were evacuated days before the explosions. The evacuation order was lifted after local officials determined it was safe to let residents return home.
"I want to once again apologize to the people of Crosby and Harris County," said Richard Rowe, CEO of Arkema North America. "The implications of the evacuation, the implications of Hurricane Harvey on our Crosby site layered upon the impact it's had on their personal lives -- I can only begin to imagine."
The Arkema plant represents just a snapshot of Hurricane Harvey's cascading effects. At least 53 people have died from the catastrophic storm, and tens of thousands of people are still living in shelters.
Toxic waste sites flooded
At least 13 toxic waste sites in Texas were flooded or damaged by Hurricane Harvey, the Environmental Protection Agency said. The 13 affected sites have industrial waste from petrochemical companies, acid compounds, solvents and pesticides.
The EPA announced over the weekend that it had assessed 41 Superfund sites using aerial images.
A Superfund site is land that is contaminated by hazardous waste and identified by the EPA as a candidate for cleanup because it poses a risk to human health and/or the environment.
The impact of flooding on the sites is unknown. The EPA said its workers have not been able to "safely access the sites" but are ready to do so as soon as the floodwaters recede.
In the Houston area, authorities had said it would take 10-15 days for floodwaters to recede.
Mayor: Houston open for business
Most of Houston is operational and more than 95% of the city is dry, Mayor Sylvester Turner told CBS' "Face the Nation" on Sunday. He said most businesses will reopen Tuesday.
"And so if you have a conference, a convention, a concert, any of those things that were planned, that you were planning to come to this city, we are still ready to welcome you," he said. "On Tuesday we are getting back on our feet, and I'm expecting employees -- employers to open, employees to go to work. And all city employees, you are due back at work on Tuesday."
But Turner said residents are still struggling, and first responders will continue going door-to-door to check on the elderly, housing conditions and disabled people.
Mexico set to send help
Relief supplies and up to 50 Mexican medical professionals will soon cross the border to help thousands of flood evacuees in Texas, Mexican officials said.
Mexico offered the United States aid last week, and Texas officials gave Mexico the green light Saturday to start sending help, said Carlos Manuel Sada, Mexico's undersecretary for North-American relations.
More than a dozen trailers loaded with beds, portable generators, mobile community kitchens and other supplies will cross the border into Laredo, Texas, "in the coming days" and be taken to the Houston area.
"On top of everything, there is a deep relationship between Mexico and Texas," Sada said.
In 2005, Mexico sent drinking water and a convoy of soldiers among other supplies to help Hurricane Katrina victims.
As the government works to help those affected by Harvey, Hurricane Irma
is looming in the Atlantic as a threat to Caribbean islands -- and potentially, by next week, to the United States.