Before restoring service after an outage (necessitated from any number of causes) the system is flushed to ensure that only clear water with the correct chemical purification levels is in the water main system. If one turns on water from the mains through their service before the all-clear is given (usually by the health department), they risk discolored and non-potable water at their discharge points. If the municipality has declared the system ready for use and there is harm from non-potable water in the mains, they're liable. The water in the line connecting your household piping to the main will need to be flushed after an all clear from the city. This requires only a few (usually less than 10) gallons to ensure you are receiving potable water at your tap. If, while the system is "officially out of service", you open your tap(s), there is no telling what you are allowing into your private service piping and the city bears no responsibility for damage. That's why they have "boil water" alerts. But boiling will have no effect on some chemical pollutants, lead contamination, for instance.
The piping in almost every municipal system in the nation is in need of some maintenance. Many systems are made of materials long past their designed use durations. Some have systemic problems which require replacing valves, replacing deteriorating pipe and/or repair of joint leakage. Other systems need new or reconditioned purification facilities or upgrading wells, towers, pumps and telecom/switch gear infrastructure. In some rare cases it may require only be a few thousand dollars but in most the bill starts at the $100,000,000 mark and in some will require at least several billions of dollars.
Our news sources do us little service when they report incorrect data about issues because they do not understand the issue or when they relate testimony from those who intentionally misinform the reporter. I'm not picking Democracy Now out. I'm referring more to the reporting about Detroit's water problems. I feel that the media has, sometimes intentionally, confused the issue to the extent that the whole thing has become a controversial because so many simply don't understand the facts, a debate more than a path forward toward solution. Engineers know the solution, city accounting dreads the price tag on engineer's solution, ambitious politicians want to steer away from advocating these devastatingly costly solutions even though they will only grow more problematic, history discounts civilizations to collapse when they cannot provide water to their citizens.
BTW, 2-3 drops of most liquid household bleaches will render 1 gallon of pond or stream water safely drinkable. It may still smell of chlorine or sewer, but it won't kill you. Scouts honor.
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