(CNN) Nearly a month after Hurricane Maria wreaked havoc on the island, Puerto Rico is still desperate for aid and basic necessities like electricity and water.

Maria devastated the infrastructure of the US territory, bringing down the energy grid and leaving more than 3 million American citizens without power. As of Sunday, 85% of the island still had no electricity.

Puerto Rico Gov. Ricardo Rosselló said he hopes that power will be restored to 95% of the island's energy grid by December 15.

"This is an aggressive agenda, but we cannot be sort of passive in the face of Puerto Rico's challenges," Rosselló said. "We are going to need all hands on deck."

During a news conference Saturday, Rosselló said his goal is to have 30% of the island's power restored by the end of the month. After that, the target would be to restore 50% by November 15 and 80% by December 1.

Authorities had estimated it could take them between six months to a year to restore power.

"Our goal as government is to give Puerto Ricans access to electricity with speed and efficiency," he tweeted.

The US Army Corps of Engineers will have to play a key role in making this plan a reality, because they have the resources and can hire the manpower that the island's agencies lack, the governor said.

The Corps has been working on the island for a few weeks, ever since FEMA tasked them with helping rebuild the island's infrastructure. They have been installing power generators, temporary roofs and reinstalling transmission lines.

The governor's announcement comes after a failure in the "central system" caused the percentage of customers with power to go down Friday.

Living without power

Puerto Ricans have been depending heavily on generators, using them to power lifesaving machines like ventilators and dialysis equipment, as well as to keep fans, air conditioners and stoves functioning.

The lack of power has forced lifestyle changes on the island. Credit and debit cards are useless. ATMs are out. No Internet, television or air conditioning. Dead cellphone batteries. Everything from the water supply to sewage treatment to the preservation of food is threatened.

In the immediate aftermath of the hurricane, a shortage of fuel made things worse.

People would line up for hours at gas stations hoping to get a few gallons for their generators. Patients at a children's hospital in San Juan were in danger due to a diesel shortage.

Now, big stores and restaurants have reopened because they are powered by generators. But Rosselló said he knows generators are just a temporary fix and will eventually also need repairs.

Power woes

Puerto Rico's power grid was a mess well before the storm.

The island's electric utility filed for bankruptcy in July and officials had said the system was "vulnerable and fragile," and in urgent need of maintenance.

Read more: Survivors of Hurricane Maria desperately need aid

Part of the problem was a shortage of employees. Many workers recently retired or left their jobs for better prospects on the US mainland, Ricardo Ramos Rodríguez, the director of Puerto Rico's power utility told CNN affiliate WAPA.

Desperate for drinking water

Many residents of the island are also grappling with a shortage of clean drinking water.

Some are so desperate, they're drinking straight from a Superfund site, according to a Friday report from CNN's John Sutter.

The water, distributed from a well at the Dorado Groundwater Contamination Site, could be polluted with chemicals that "can have serious health impacts including damage to the liver and increasing the risk of cancer," according to the Environmental Protection Agency.

As of Sunday, more than 30% of Puerto Ricans were without access to potable water, according to the island's water utility, Autoridad de Acueductos y Alcantarillados (AAA), which distributed the contaminated water.

Luis Melendez, sub-director for environmental compliance at AAA, said the utility didn't know the well was a designated Superfund site before CNN provided maps showing that was the case.

Following the CNN report on the hazardous water, Rep. Bennie Thompson of Mississippi, ranking Democrat on the House Homeland Security Committee, asked Homeland Security Secretary Elaine Duke to investigate the matter.

The Department of Homeland Security didn't respond to a request for comment from CNN on Saturday.

Read more: Puerto Rico's death toll from Hurricane Maria climbs to 48

Gov. Rossello told CNN Sunday that one of wells on the site -- the Santa Rosa well -- has been certified by the territory's Department of Health as safe to drink.

But Gary Lipson, incident commander for the EPA in Puerto Rico, said samples to test for chemical contamination must be shipped to the mainland US, and would take a few days to get back.