Millions of Texans still scramble for drinking water after devastating winter storm

A historic winter storm that knocked out power and froze pipes across Texas has left many families scrambling for safe drinking water.

More than 1,100 public water supply systems reported weather-related disruptions in service on Friday morning, impacting over 14.4 million people, about half of the state's population. Many of those affected remain under a boil-water advisory due to concerns about potential contamination, according to a spokesperson for the Texas Commission on Environmental Quality.

Water treatment plants across Texas have suffered power outages since a storm swept in earlier this week, blanketing the Lone Star State in snow and ice. Boil-water advisories remain in effect for most of the state's major cities, including Austin, Arlington, Galveston, Houston, San Antonio and parts of Forth Worth.

Houston Mayor Sylvester Turner, who said a pipe burst in his own home, has warned residents to be prepared to boil their water -- if they have any -- before consumption or use until at least Sunday or Monday.

Many people still don't have water or lack power to boil it. There were 189,865 customers without power in Texas on Friday morning, down from a peak of over 4.4 million on Monday, according to data collected by PowerOutage.US.

The Public Utility Commission of Texas, which regulates the state's electric, water and telecommunication utilities, issued an order on Wednesday evening, mandating that all electric transmission and distribution utilities perform rolling blackouts so that no customer is without power for more than 12 hours.

The Electric Reliability Council of Texas (ERCOT), the nonprofit corporation responsible for managing 90% of the state's electricity, said it expects to come out of emergency conditions later Friday morning. ERCOT president and CEO Bill Magness admitted during a press briefing Thursday that the Texas power grid was just "seconds or minutes" away from a complete and catastrophic failure, as power demand increased and generators fell offline on Sunday night amid the snowstorm. Magness said it could have taken months to restore.

Texas Gov. Greg Abbott lambasted ERCOT for its handling of this week's storm and urged lawmakers to pass legislation to ensure the grid would be better prepared in the future.

"What happened is absolutely unacceptable and can never be replicated again," Abbott said at a press conference Thursday. "Texans deserve answers about why these shortfalls occurred and how they will be corrected."

The extended power outages combined with record-low temperatures caused freezing pipes to burst across Texas, plummeting pressure and depleting reserves. Residents, businesses and even hospitals are being asked to conserve water as cities race to restore and stabilize their water supply.

Two C-17 military transport aircraft are heading to Galveston and Corpus Christi to deliver water and other supplies, likely on Friday, a senior U.S. defense official told ABC News. The help comes at the request of the Federal Emergency Management Agency following a plea from Abbott. There are currently no plans to use federal troops for ground-based support in Texas, though FEMA will be sending non-military personnel, the official said.

The Texas National Guard remains active across the state, helping local authorities get citizens to warm shelters and provide other life-saving assistance.

Meanwhile, crews worked throughout the night on Thursday to set up a mass bottled water distribution site at Houston's Delmar Stadium. The site was expected to begin distribution on Friday at 11:30 a.m. local time.

In Galveston, a line of cars wrapped around city blocks on Wednesday evening as people waited to collect free water bottles at a distribution site. Much of the island city is still without water or under a boil-water advisory.

Gas stations were also packed with cars this week, as people fear running out of fuel for their vehicles or generators. One resident, Robert Neuman, told Houston ABC station KTRK that he has already made multiple trips, admitting he "wasn't prepared" for the storm.

"Like everyone, we figured it would get cold and maybe a little outage and that's it," Neuman said. "But we've been going since Sunday like this."

ABC News' Jenna Harrison, Will McDuffie, Matt Seyler and Gina Sunseri contributed to this report.