For many of those who do have functioning plumbing, the water is not safe to drink.

Governor Greg Abbott today temporarily waived certain regulations from the Department of Motor Vehicles to aid in the response to winter weather and power outages throughout the state.

White House homeland security adviser Liz Sherwood-Randall told reporters earlier that 1 million or more people were still suffering power outages as a result of the storm and blamed it on climate change, which some Republican officials in affected states have denied or downplayed.

And more than 100,000 customers remained without power Thursday in OR, a week after a massive snow and ice storm.

Better forecasting - both short-term and long-term - would help avoid catastrophic failures such as the current outages in Texas and other states, as would large-scale storage systems that can supply electricity when demand spikes and a greater diversity of power sources, Eftekharnejad and other experts said.

Meanwhile, heavy snow and ice were expected on Thursday in the Appalachians, northern Maryland and southern Pennsylvania, with the wintry weather moving into the Northeast by nightfall. "We're to the point in the load restoration where we are allowing transmission owners to bring back any load they can related to this load shed event", Woodfin said.

In the Houston area, a family died from carbon monoxide as their vehicle idled in their garage. Elsewhere, a grandmother and three children died when flames escaped the fireplace they were using to keep warm.

Utilities from Minnesota to Texas implemented rolling blackouts to ease the burden on strained power grids.

While welcoming the progress, other leaders in Texas warned that the state's energy grid would remain extremely "fragile" for a few days and that the cold weather that created the problems would stick around through the weekend.

Without mentioning any troubles with natural gas, he said that "our wind and our solar got shut down, and they were collected more than 10 percent of our power grid", and "that thrust Texas into a situation where it lacked power".

Deadly weather will be hitting the USA more often, and America needs to get better at dealing with it, experts said as Texas and other states battled winter storms that blew past the worst-case planning of utilities, governments and millions of shivering residents.

Authorities ordered seven million people - a quarter of the population of the nation's second-largest state - to boil tap water before drinking it, following the record low temperatures that damaged infrastructure and pipes.

Statewide, water pressure has fallen because of frozen lines, Toby Baker, executive director of the Texas Commission on Environmental Quality said.

Trilby Landry, a 57-year-old homeless man, was escaping the cold at the Gallery Furniture store in Houston that had opened its doors as a warming center, joining people who had fled homes with busted heating systems and water pipes.

The Texas Electric Reliability Council, which plays the role of Texas power traffic officer directing energy from producers to distributors, predicted that the wind will generate about 7,070 megawatts at peak load times this winter.

"The entire system was overwhelmed", said Joshua Rhodes, a research associate on energy issues at the University of Texas.

In Austin, some hospitals faced a loss in water pressure and in some cases, heat. But because the problem was statewide and affected other facilities, "no one hospital now has the capacity to accept transport of a large number of patients", said David Huffstutler, CEO of St. David's South Austin Medical Center.

Two of Houston Methodist's community hospitals had no running water but still treated patients, with most non-emergency surgeries and procedures canceled for Thursday and possibly Friday, said spokeswoman Gale Smith.

Emergency rooms were crowded "due to patients being unable to meet their medical needs at home without electricity", Smith said.

The latest storm front was certain to complicate recovery efforts, especially in states that are unaccustomed to such weather - parts of Texas, Arkansas and the Lower Mississippi Valley.

Another in Houston had to haul in water on trucks to flush toilets. For others, it meant no water at all. "We will get through this together".