A boil water advisory is a notice from your water provider that tap water may not be safe to drink without treatment, so it should be boiled first. In O'Fallon, a notice may cover a specific set of addresses or a zone rather than the whole town. The notice itself is the best source for your area, so read it closely and note whether it asks you to boil water, avoid using tap water, or both.

Advisories are often issued after a pressure drop, a main break, a treatment problem, or a sampling result that needs follow-up. You do not need to know the exact cause to act well. You need to know what the notice asks you to do and what it says about when the advisory ends.

While the advisory is in effect

  • Use bottled water, or water you have boiled, for drinking, brushing teeth, preparing food, washing fresh produce, and mixing infant formula.
  • To boil water, bring it to a full rolling boil, keep it there for the time the notice specifies, then let it cool in a clean, covered container.
  • Store boiled water in a clean container with a lid and keep it in the refrigerator.
  • Do not use ice from the freezer or the ice maker unless the notice says it is safe.
  • Wash dishes with boiled or bottled water, or use the dishwasher only if the notice allows it.
  • Keep children from swallowing water while bathing, and give pets boiled or bottled water too.

Before the notice is lifted

Check with your water provider for updates. The notice should state when the advisory has ended. Do not assume it is over because the tap water looks clear. Clear water can still need testing, and the provider's announcement is the signal to follow.

After the advisory ends

Water can sit in household pipes during an event, and flushing helps move that water out. Because O'Fallon tap water is commonly hard, you may also see some mineral residue in aerators after flushing, which is normal. Work through the steps below in order.

  1. Run cold water at every tap in the house, starting with the fixture closest to where the main line enters the home and working outward, for the length of time the provider recommends.
  2. Run hot water at the same taps in the same order.
  3. Flush every toilet in the house.
  4. Clean and sanitize the ice maker and its water line, then discard the first batches of ice it makes.
  5. Unscrew faucet aerators and shower heads, rinse away debris and residue, and put them back.
  6. Replace filter cartridges in refrigerators, pitcher filters, and any whole-house units that were in use during the advisory, following the manufacturer's cleaning and replacement guidance.
  7. If you have a water softener, check the brine tank and follow the softener manual for any post-event steps it recommends.
  8. If the water heater was idle during the advisory, or the notice recommends it, drain and flush the tank according to the heater's manual.

Testing when you are unsure

If you still have concerns after the advisory ends, a water test gives you better information than guessing. For a home served by a city water system, you can ask your provider for recent results covering your address. For a home on a private well, the Missouri State Public Health Lab offers coliform and E. coli testing at free or low cost, and it also offers testing for iron bacteria, which can leave slime and odor problems behind.

If your home uses a private well

A city boil water notice does not apply to a private well in the same way, but a well can still be affected by heavy rain, flooding, power loss, or nearby ground disturbance. If you notice a change in clarity, odor, or taste, or if your household experienced a recent event that affected the water supply, consider testing the well before using it for drinking. Keep a simple record of the date, what you noticed, and any test results so you can compare them over time.

Keeping it simple

A boil water advisory is a short-term instruction, and the steps are straightforward. Follow the notice, use boiled or bottled water until the advisory is officially lifted, flush your plumbing and clean the fixtures that hold water, and test if anything still seems off. In O'Fallon, that routine covers most of what a homeowner needs to do.