First Texans lost their power. Now, they’re losing their potable water.

After enduring multiple days of freezing temperatures and Texans dripping faucets to prevent frozen pipes from bursting, cities across the state warned residents on Wednesday that water levels are dangerously low and may be unsafe to drink.

Many Texas cities are issuing boil notices — asking residents to boil tap water for drinking, cooking, brushing their teeth and for making ice — as residents have been struggling to maintain power and heat while an unprecedented winter storm whips across the state.

“Water pressure is very low. Please do not run water to keep pipes from bursting,” Houston Mayor Sylvester Turner tweeted Wednesday morning.