JOLIET, ILLINOIS · 2025 WATER DATA
Is Joliet's water good enough for your family?
Joliet's water meets federal standards. But a legal limit is not a health goal. Every figure on this page comes from City of Joliet's published reporting — and every one is system-wide, not from your tap.
THE SUPPLIER
City of Joliet
Groundwater from twenty-one deep bedrock wells and five shallow gravel wells. The water naturally contains radium, iron, and manganese, which the City removes at eleven treatment plants before disinfecting it and adding a corrosion-control phosphate.
Source: City of Joliet 2025 Drinking Water Quality Report (published June 2026)
- The City of Joliet's service line map lists 306 lead service lines and 4,159 "unknown – assumed lead" out of 49,262 addresses.
- In 2025 lead sampling, the 90th-percentile result was 9.03 ppb, below the 15 ppb action level, but 6 sites were above the action level and the highest result was 88.7 ppb.
- The City says Joliet tap water is hard: about 22 grains per gallon east of Midland Avenue and 12 west of it.
- Joliet is a member of the Grand Prairie Water Commission, which expects to deliver Lake Michigan water to member communities by 2030.
Two things to know
These are town-wide results. What comes out of your tap also depends on your own pipes and faucets. A town report can't see inside your house.
Legal limit isn't the same as the health goal. The legal limit is the most the law allows. The health goal is the level with no known risk. For lead, the health goal is 0.
JOLIET WATER REPORT CARD
What Joliet's own water reports show.
Here's what Joliet's own water reports say, in plain English. Green means it looks good. Yellow means keep an eye on it. Red means it needs attention.
ppb = parts per billion. 1 ppb is about 1 drop of water in a backyard swimming pool.
The short version
- Some tested homes were over the lead action level
- A few street water pipes are still lead or unknown
- Some copper found, under the action level
- Some homes were built before lead solder was banned
- Hard water — spots and scale, not a health issue
- Chlorine by-products (TTHM) are low
Lead in tested homes
Lead · 90th percentile
Needs attention
The town tests tap water in homes most likely to have lead. 9 out of 10 of those homes had this much or less.
9.03 ppb
parts per billion
Action level: if more than 1 in 10 tested homes go over this, the town must take extra steps.
Highest single test: 88.7 ppb
6 tested homes had more lead than the 15 ppb action level. A drinking-water filter certified for lead can help.
Source: City of Joliet 2025 Drinking Water Quality Report (published June 2026)
Chlorine by-products
Total trihalomethanes (TTHM)
Looks good
Leftovers that form when chlorine cleans the water. The law limits them because drinking too much over many years may raise health risks.
2 ppb
parts per billion
Legal limit: the most the law allows.
Far below the 80 ppb legal limit.
No action needed
Source: City of Joliet 2025 Drinking Water Quality Report (published June 2026)
Lead water pipes from the street
Service-line inventory
Keep an eye on it
A service line is the underground pipe that brings water from the street into a building. Some old ones are made of lead.
306 of 49,262 street water pipes are lead
Fewer than 1 in 10
The City labels its 4,159 unknown lines "unknown – assumed lead" until they're checked. The map also lists 39 galvanized lines and 84 addresses without a classification.
Most street water pipes are not lead, but 306 lead pipes and 4,159 unknown or old steel pipes remain on the town's list. Check your address — if your home has one, a drinking-water filter certified for lead can help until it's replaced.
From the town's list, as of September 27, 2026.
Source: City of Joliet water service line material map (retrieved September 27, 2026)
Older homes
Homes built before 1980
Good to know
Lead solder and lead pipes were allowed in homes until 1986.
47.1%of Joliet homes were built before 1980 — about 5 in 10Older homes are more likely to have lead solder inside.
Source: U.S. Census Bureau, ACS 2024 5-year estimates (B25034)
Tested homes over the lead limit
Lead sampling
Needs attention
6tested homes had more lead than the 15 ppb action level6 tested homes had more lead than the 15 ppb action level. A drinking-water filter certified for lead can help.
More chlorine by-products
Haloacetic acids (HAA5)
Looks good
Another group of chlorine leftovers, also limited by law.
3 ppb
parts per billion
Legal limit: the most the law allows.
Far below the 60 ppb legal limit.
No action needed
Source: City of Joliet 2025 Drinking Water Quality Report (published June 2026)
Copper in tested homes
Copper · 90th percentile
Keep an eye on it
Copper can get into water from pipes inside homes.
1.01 ppm
parts per million
Action level: if more than 1 in 10 tested homes go over this, the town must take extra steps.
Under the 1.3 ppm action level. Copper usually comes from pipes inside the home.
Source: City of Joliet 2025 Drinking Water Quality Report (published June 2026)
Hard water
Water hardness
Good to know
Minerals that leave white spots and scale.
22 gpggrains per gallon
Hard water leaves white spots and scale. It's a comfort issue, not a health limit.
Typical home age
Median year built
Good to know
Half of Joliet's homes were built before this year.
1985Older homes are more likely to have lead solder inside.
Source: U.S. Census Bureau, ACS 2024 5-year estimates (B25035)
Where the water comes from
Groundwater from twenty-one deep bedrock wells and five shallow gravel wells. The water naturally contains radium, iron, and manganese, which the City removes at eleven treatment plants before disinfecting it and adding a corrosion-control phosphate.
Source: City of Joliet 2025 Drinking Water Quality Report (published June 2026)
WATER WORDS, EXPLAINED
What these Joliet water report words mean
- ppb (parts per billion)
- 1 ppb is about 1 drop of water in a backyard swimming pool.
- ppm (parts per million)
- 1,000 times more than a ppb — about 1 drop in 13 gallons.
- Legal limit (MCL)
- The most of something the law allows in public drinking water.
- Action level
- A trigger for lead and copper. If more than 1 in 10 tested homes are over it, the water system must take extra steps.
- Health goal (MCLG)
- The level with no known health risk. For lead, it's 0. Health goals are not legal limits.
- 90th percentile
- Line up all the test results from lowest to highest. The 90th percentile is the number that 9 out of 10 results are at or below.
- Service line
- The underground pipe that carries water from the main under the street into a building.
- Galvanized pipe that needs replacing
- An old steel pipe coated in zinc. If it was ever connected after a lead pipe, it can hold lead and must be replaced.
- TTHM (total trihalomethanes)
- Leftovers that form when chlorine mixes with natural material in water. The law limits them because drinking too much over many years may raise health risks.
- HAA5 (haloacetic acids)
- Another group of chlorine leftovers, also limited by law.
- PFAS
- A big family of man-made chemicals, sometimes called "forever chemicals" because they break down very slowly.
- Reverse osmosis (RO)
- A filter that pushes water through a very fine layer to remove many things. It sits under the kitchen sink and gives you one tap of filtered drinking water.
- Whole-home carbon filter
- A large filter where water enters the house. It removes chlorine taste and smell at every tap.
- Water softener
- Removes the minerals that make water "hard" — the white spots and scale. It does not remove lead.
- NSF/ANSI certification
- An independent lab test proving a filter really reduces what it claims. We list the exact certificate on your quote.
WHICH FILTER FIXES WHAT
Which filter fixes which problem?
Find your problem on the left. A green check means that system helps.
Yes, it helps Only certain models No, it doesn't
| Water problem | Under-sink ROFilters drinking water at the kitchen sinkfrom $1,195 | Whole-home carbonFilters all the water coming into your housefrom $1,795 | Water softenerStops hard-water spots and scalefrom $1,795 | Complete Home SystemAll three togetherfrom $2,699 |
|---|---|---|---|---|
| Lead | Yes — certified to reduce lead (NSF/ANSI 53/58) | No — doesn't remove lead | No — doesn't remove lead | Yes — at the kitchen sink (through the RO) |
| Chlorine by-products (TTHM) | Yes — certified to reduce TTHM (NSF/ANSI 53/58) | Only some models — ask for NSF/ANSI 53 | No | Yes — at the kitchen sink (through the RO) |
| Chlorine taste & smell | Yes — at the kitchen sink | Yes — at every tap (NSF/ANSI 42) | No | Yes — at every tap |
| Hard water & scale | No — not a softener | No — not a softener | Yes — sized to your water (NSF/ANSI 44) | Yes — whole house |
| PFAS ("forever chemicals") | Yes — certified to reduce PFOA/PFOS (NSF/ANSI 53/58) | No — not certified for PFAS | No | Yes — at the kitchen sink (through the RO) |
Lead
- Under-sink ROFilters drinking water at the kitchen sinkYes — certified to reduce lead (NSF/ANSI 53/58)
- Whole-home carbonFilters all the water coming into your houseNo — doesn't remove lead
- Water softenerStops hard-water spots and scaleNo — doesn't remove lead
- Complete Home SystemAll three togetherYes — at the kitchen sink (through the RO)
Chlorine by-products (TTHM)
- Under-sink ROFilters drinking water at the kitchen sinkYes — certified to reduce TTHM (NSF/ANSI 53/58)
- Whole-home carbonFilters all the water coming into your houseOnly some models — ask for NSF/ANSI 53
- Water softenerStops hard-water spots and scaleNo
- Complete Home SystemAll three togetherYes — at the kitchen sink (through the RO)
Chlorine taste & smell
- Under-sink ROFilters drinking water at the kitchen sinkYes — at the kitchen sink
- Whole-home carbonFilters all the water coming into your houseYes — at every tap (NSF/ANSI 42)
- Water softenerStops hard-water spots and scaleNo
- Complete Home SystemAll three togetherYes — at every tap
Hard water & scale
- Under-sink ROFilters drinking water at the kitchen sinkNo — not a softener
- Whole-home carbonFilters all the water coming into your houseNo — not a softener
- Water softenerStops hard-water spots and scaleYes — sized to your water (NSF/ANSI 44)
- Complete Home SystemAll three togetherYes — whole house
PFAS ("forever chemicals")
- Under-sink ROFilters drinking water at the kitchen sinkYes — certified to reduce PFOA/PFOS (NSF/ANSI 53/58)
- Whole-home carbonFilters all the water coming into your houseNo — not certified for PFAS
- Water softenerStops hard-water spots and scaleNo
- Complete Home SystemAll three togetherYes — at the kitchen sink (through the RO)
Filter claims apply to the exact certified model named on your quote, used and maintained the way the maker says.
COMPLIANCE
Reported compliance notes
The 2025 report lists a minor routine monitoring violation (January 2023–December 2025) for PCBs: samples were collected and all results met EPA standards, but the contract lab's results reached Illinois EPA late because of a computer upload failure.
Source: City of Joliet
What this page cannot tell you
These are town-wide results. What comes out of your tap also depends on your own pipes and faucets. The only way to know for sure is to test your own water — we'll tell you that even when it means you don't buy anything from us.
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