President Joe Biden has declared a major disaster in Texas, clearing the way for more federal funds to be spent on relief efforts in the US state.
Power is returning across Texas and temperatures are set to rise, but some 13 million people are still facing difficulties accessing clean water.
Mr Biden has said he will visit Texas as long as his presence is not a burden on relief efforts.
Nearly 60 deaths have been attributed to cold weather across the US.
In a statement released by the White House, President Biden said he had “ordered federal assistance to supplement state and local recovery efforts in the areas affected by severe winter storms”.
“Assistance can include grants for temporary housing and home repairs, low-cost loans to cover uninsured property losses, and other programmes to help individuals and business owners recover from the effects of the disaster,” the statement said.
Mr Biden has been in touch with the mayors of some of Texas’ biggest cities, such as Houston, Austin and Dallas, to ensure they have access to government resources, an administration official said.
Several other southern states hit by snow and ice storms this week have also reported water service outages.
Winter weather has also cut off water in the city of Jackson, Mississippi – home to around 150,000 people – as well as the largest county in Tennessee that includes the city of Memphis, with more than 651,000 residents.
Across the US South, a region unaccustomed to such frigid temperatures, people whose pipes have frozen have taken to boiling snow to make water.
The south-western state’s energy grid has been overwhelmed by a surge in demand for heat as temperatures plummeted to 30-year lows, hitting 0F (-18C) earlier this week.
As of Friday, about 180,000 homes and businesses in Texas still had no electricity. Amid freezing temperatures earlier this week, as many as 3.3 million were without power.
Around 13 million people – close to half of the state’s population – have faced some disruption of water services as hundreds of water systems have been damaged by the freeze.
Austin, the state’s capital, lost 325 million gallons (1.2 billion litres) of water when pipes burst, the city’s water director told reporters on Thursday.
Texas’ largest city, Houston, is under a so-called “boil water notice”, with the US Centers for Disease Control and Prevention (CDC) advising that all water planned for consumption – even if filtered – must be boiled as it may be contaminated.
Officials there say they are working to rapidly distribute bottled water, as well as power generators, to people in need. Breweries and other local businesses have also assisted with efforts to supply drinkable water.
On Friday, Texas Governor Greg Abbott said the state was providing “any and all resources to assist and to accelerate the response at the local level”.
State officials could not offer a timeline for exactly when the water would come back on, saying it was a question for local water providers – and many have not yet fully assessed the damage to their systems.
Gov Abbott also said more plumbers are headed to the state. Water pipes have been bursting across Texas due to the freeze, and local plumbers have struggled to meet demand.
Over 320 plumbers have renewed their licences, and the state agencies are working with out-of-state plumbing companies to secure additional help, he said.
New York congresswoman Alexandria Ocasio-Cortez said on Saturday she had raised more than $3m (£2.1m) in donations as part of relief efforts for Texas.
“When you already have so many families in the state and across the country that are on the brink, that can’t even afford an emergency to begin with, when you have a disaster like this, it can just set people back for years, not just for days,” she said, speaking at a Houston food bank.