Guides
Daily news explainers: How Chicago boil orders work
Daily news explainers: How Chicago issues and lifts boil orders, what residents should do, and why a water main break can trigger one.
What to take away
- A Chicago boil order follows a loss of pressure in the mains, not the break itself. A break repaired before the section drains may never produce one.
- The Chicago Department of Water Management issues the order, collects the samples and lifts it. Illinois EPA reviews the results first.
- The order covers drinking, cooking, ice, formula and brushing teeth. Water keeps flowing, and routine bathing and flushing usually continue.
- Clearing takes at least two consecutive rounds of clean bacteria samples, which is why the order outlasts the repair by a day or more.
- Call 311 for a break, low pressure or discolored water. Check the Department of Water Management's water pages and city alerts for the boundary and lifting notice.
Why pressure loss, not the break, triggers the order
A main break drops pressure in the pipes around it. When pressure falls, groundwater and soil can enter through cracks and joints. That is the risk the order addresses. In daily news explainers about Chicago water, the key point is that a break alone does not trigger a boil order: pressure loss creates the contamination risk.
Chicago's system is old and vast, so breaks are routine. The city's water pages treat main breaks and boil orders as recurring events rather than rare emergencies, which makes the City of Chicago water management pages the first stop for residents.
Bacteria such as E. coli and coliform are the concern. They indicate the water may have picked up contamination from surrounding soil or from a cross-connection.
The city also issues precautionary orders when main work could introduce contamination without a confirmed break. Crews would rather over-warn than under-warn.
A water main break and a boil order are different developments: the break can cause pressure loss, but an order addresses the resulting risk to water quality. The drinking water advisory desk case explains how to distinguish an advisory from other health alerts.
How the Department of Water Management issues an order
Issuance is a sequence, not a single announcement.
How a Boil Order Is Issued
- Crews flag pressure loss or break
- Department maps affected zone
- Illinois EPA notified, notice prepared
- Order sent via alerts, media, door hangers
- Sampling points set, order clock starts
- Crews or a pressure monitor flag a loss of pressure or a confirmed break in a defined area.
- The department maps the affected zone by address and block.
- It notifies Illinois EPA and prepares a public notice with the boundary and the reason.
- The department shares the notice through city alert channels, local media and door hangers in the zone.
- Sampling points are set, and the clock on the order starts.
The notice names the boundary, so residents can check whether their block is inside it. Check the notice against your address; if your address is not listed, you are not under the order.
Federal drinking-water public-notice regulations under the Safe Drinking Water Act include Tier 1 notices for situations that may pose an acute health risk. The Revised Total Coliform Rule sets requirements for monitoring and responding to coliform findings. The EPA ground water and drinking water pages explain the federal framework.
One zone gets one order. A single building with its own internal problem may get a building-specific notice instead.
Residents should keep the order notice and any update so they can verify the affected boundary and when the order was issued. The lifting notice confirms when the order is over.
What the order requires of residents
Illinois EPA oversees the city's sampling and reviews the results before an order is lifted. The household rules come from CDC guidance, which applies to any boil water notice in the country.
Household Boil Order Rules
- Boil water one minute, then cool
- Use boiled or bottled water for drinking
- Use boiled water for cooking and ice
- Do not wash raw produce with tap water
- Wash dishes with boiled water or sanitizing cycle
- Give pets boiled or bottled water
- Discard ice made during the order
- Bring water to a rolling boil for at least one minute, then let it cool.
- Use boiled or bottled water for drinking, cooking, ice, baby formula and brushing teeth.
- Do not use tap water to wash fresh produce you will eat raw.
- Dishes are safe if washed in hot soapy water and rinsed in boiled water, or run through a dishwasher on a sanitizing cycle.
- Hand washing is fine with soap and tap water for most routine purposes.
- Pets need boiled or bottled water too.
- Discard ice made during the order and any drinks mixed with tap water.
Boiling is the reliable step. Filters do not remove bacteria, and neither does freezing.
For another guide to interpreting a public health notice, see the health alert reporting checklist.
The roles differ. Illinois EPA regulates the system and enforces the sampling. The CDC publishes the household guidance. The EPA page on state drinking water requirements explains how states carry out federal rules.
What a boil order does and does not cover
A boil order is narrower than most residents assume.
It covers anything that goes in your mouth: drinking, cooking, ice, formula and brushing teeth. It covers water given to pets.
It does not shut off your supply. Water keeps flowing, which is why the order exists. The water is available but suspect.
It does not usually restrict showering or bathing, as long as you do not swallow the water. It does not restrict flushing toilets or washing hands with soap.
It does not cover a whole city. Orders are drawn to a zone, often a few blocks or a single neighborhood.
It is not a sign of confirmed contamination. Most orders are lifted without a single positive sample.
This order applies only to the Chicago zone named in its notice. Other large systems, such as Houston, issue their own advisories for their own boundaries.
For how advisories differ by type and by evidence, see the health evidence alert types comparison.
How the city tests and clears an order
Clearing a boil order is a testing process with a fixed shape.
How a Boil Order Is Cleared
- Crews repair main and restore pressure
- Department flushes affected mains
- Sampling teams collect bacteria samples
- First round must come back clean
- Second round must also come back clean
- Illinois EPA reviews results and lifts order
- Crews repair the main and restore pressure to the zone.
- The department flushes the affected mains to move out stagnant or suspect water.
- Sampling teams collect bacteria samples from points across the zone.
- A first round must come back clean. A second round, collected after the first, must also come back clean.
- Illinois EPA reviews the results, and the department lifts the order.
Two consecutive clean rounds are the standard because a single sample can miss contamination. The gap between rounds is what makes clearing take a day or more.
Once the order is lifted, the department notifies residents through the same channels used for the notice. Run cold taps for a few minutes, dump ice made during the order, and flush water lines in appliances.
A positive sample keeps the order in place and restarts the process. That is uncommon, but it happens.
Residents ask why the order lasts after the repair is done. The repair restores pressure. The sampling proves the water is safe.
Where residents get updates and report problems
Call 311 for water service issues, including breaks, low pressure and discolored water. The city's water pages carry service information and links to current notices.
Sign up for NotifyChicago, the city's alert system, and check the Department of Water Management's water pages for current order boundaries and lifting notices. Local coverage can provide additional updates; the local media guide explains how news updates develop. Illinois EPA posts information about drinking water systems and notices on its own site, and the CDC's boil water pages carry household guidance in printable form.
A lifting notice should say explicitly that the order is over. Check the Department of Water Management's water pages and city alerts for that notice before assuming the water is clear.
Report problems that persist after an order is lifted: continued discoloration, odd taste or smell, or low pressure. Those can signal a second issue.
When reading an order notice, check its boundary, reason and lifting language. The guide to reading a public health notice covers those details, and the health alerts medical news reporting guide covers the wider beat.
Common questions
How long do Chicago boil orders usually last?
Most clear within a day or two. The order stays until two consecutive rounds of bacteria samples come back clean and Illinois EPA reviews them.
Does a boil order mean the water is contaminated?
No. Most orders are precautionary and are lifted without any positive sample. They follow pressure loss, which creates a risk, not a confirmed finding.
Who issues and lifts a boil order in Chicago?
The Chicago Department of Water Management issues it, samples the zone and lifts it, with Illinois EPA oversight and review of the results.
What should I do after the order is lifted?
Run cold taps for a few minutes, discard ice made during the order, and flush water lines in appliances such as coffee makers and refrigerators.
