A major water main break in Danbury has been repaired, but thousands of residents are still under a boil water advisory. City officials say the break on Sand Pit Road left about 30,000 people without drinkable water on Christmas Day. Repairs were completed by early Thursday morning, but testing is still underway to confirm the water is safe. Until results are cleared, residents in the low service area are told not to drink tap water or use it for cooking or brushing teeth unless it is boiled. Test results are expected today.