Capitol Water Corp water quality
Boise City, ID · serves 9,000 people (2,811 connections) · Groundwater · Private · EPA ID ID4010022
Data: U.S. EPA · How we read the data · How we check it
Summary
PFAS above the 2024 federal limits. Systems have until 2029 to meet the PFAS limits.
Is it an emergency? No: PFAS limits are about years of exposure, not a glass of water, and nothing in EPA's data calls for you to stop drinking the water today. If your utility ever issues a boil-water or do-not-drink notice, follow it.
- PFAS
- Above limitPFOA, PFOS, PFNA, the PFAS Hazard Index above the federal limit in EPA's 2023–2025 testing (PFOA 5.8 ppt vs a limit of 4 ppt, PFOS 9.45 ppt vs a limit of 4 ppt, PFNA 37.5 ppt vs a limit of 10 ppt, where ppt = parts per trillion).
- Lithium
- Above screening levelHighest result 24 ppb. EPA uses 10 ppb to decide what to study further. It is not a health limit, and there is no federal limit for lithium. About 1 in 4 systems tested were above it.
- Lead
- Below action level3 ppb (parts per billion) at the 90th percentile: 9 in 10 homes sampled were at or below it. Action level 15 ppb, falling to 10 ppb in Nov 2027. Monitoring period Jan 2024 – now, still in progress (results reported so far). Your home's pipes can make yours higher.
- Violations
- Resolved3 health-based violations since 2016, most recently Apr 2025.
- Pregnant, or mixing baby formula with tap water? Babies drink more water for their size, so PFAS exposure matters more for them. Consider bottled water or a filter certified for PFAS for formula, and ask your doctor. Health effects.
- To lower your PFAS exposure now, a home filter certified for PFAS reduction works (reverse osmosis, or activated carbon certified to NSF/ANSI 53 or 58). Filters for these results.
- Built before 1986, or not sure what your service line is made of? Check your service line and test your tap. Utility data can't show your pipes.
- Tested your own tap? Compare your result with these numbers. Moving? Compare this system with another.
- Read Capitol Water Corp's annual water quality report (Consumer Confidence Report). It lists every regulated contaminant tested and is usually on the utility's website or mailed with your bill, and you can also request it at (208) 375-0931. EPA: how to find it.
PFAS (“forever chemicals”)
EPA UCMR 5: 4 entry points tested Jun 2023 to Oct 2024. "Average" is the highest entry-point average (non-detects counted as zero), the way EPA compares UCMR 5 results to the limits. ppt = parts per trillion. These results do not determine compliance.
| Contaminant | Highest average |
|---|---|
| PFOA Above limit Limit 4 ppt | 5.8 ppt 1.45× the limit |
| PFOS Above limit Limit 4 ppt | 9.45 ppt 2.36× the limit |
| PFHxS Detected, below limit Limit 10 ppt | 5 ppt 50% of the limit |
| PFNA Above limit Limit 10 ppt | 37.5 ppt 3.75× the limit |
| HFPO-DA (GenX) Not detected Limit 10 ppt | – |
| Hazard Index (a combined score for PFHxS, PFNA, GenX and PFBS, where above 1 is over the limit) Above limit Limit 1 | 4 |
| PFBS Detected, below limit Guideline 2,000 ppt | 3.95 ppt |
| PFBA Not detected Guideline 6,000 ppt | – |
| PFHxA Detected, below limit Guideline 3,000 ppt | 4.9 ppt |
| PFPeA Detected, no limit | 5.1 ppt |
For context: the PFOA average is higher than at 98% of the Idaho systems EPA tested, the PFOS average is higher than at 96% of the Idaho systems EPA tested and the PFNA average is higher than at 98% of the Idaho systems EPA tested.
29 PFAS tested, 7 detected at least once. "Not detected" means below EPA's reporting limit (about 2 to 20 ppt depending on the chemical), not proven zero. PFAS not listed were not detected. The limits for PFHxS, PFNA, GenX and the Hazard Index were proposed for rescission in May 2026. That proposal is not final. Systems have until 2029 to meet the limits.
Lithium
Detected in 8 of 8 samples. Highest result 24 ppb. EPA's non-enforceable screening level is 10 ppb. Above screening level The screening level is how EPA decides what to study further, not a health limit. There is no federal limit for lithium and no filter is certified to remove it. About lithium.
Lead and copper
Latest 90th percentile: 3 ppb lead (Jan 2024 – now (in progress)). Below action level
Highest since 2016: 5 ppb (Dec 2017).
| Monitoring period | Lead (90th pct.) |
|---|---|
| Jan 2024 – now (in progress) | 3 ppb |
| Jan 2021 – Dec 2023 | 0 ppb |
| Jan 2018 – Dec 2020 | 0 ppb |
Earlier results (9)
| Jan 2015 – Dec 2017 | 5 ppb |
| Jan 2012 – Dec 2014 | 0 ppb |
| Jan 2009 – Dec 2011 | 0.4 ppb |
| Jan 2007 – Dec 2007 | 0.8 ppb |
| Jan 2006 – Dec 2006 | 1.2 ppb |
| Jan 2005 – Dec 2005 | 1.5 ppb |
| Jul 2004 – Dec 2004 | 2.1 ppb |
| Jul 2002 – Dec 2002 | 2 ppb |
| Jan 1996 – Dec 1998 | 2 ppb |
Copper 90th percentile: 3.56 ppm (Dec 1998), action level 1,300 ppb.
Lead comes from pipes and fixtures, not the source water, so it varies home to home. The 90th percentile means 9 in 10 sampled homes were at or below it. More on lead.
Violations
| When | What happened |
|---|---|
| Jan 2025 – Apr 2025 2 times | The running annual average for Combined Uranium was above the legal limit. EPA record: Combined Uranium · Maximum Contaminant Level Violation, Average · measured 31 ug/l (limit 30 ug/L) Resolved |
| Oct 2024 | The system did not publish the required inventory of lead service lines (due October 2024). It says nothing about lead levels in the water. EPA record: Lead and copper rule revisions · LSL Inventory Resolved |
1 unresolved monitoring or reporting violation: Public Notice.
Health-based violations mean a contaminant exceeded a limit or a required treatment step was missed. Monitoring and reporting violations mean required tests or reports were late or missing, so the water's quality during that time is unknown. The total includes every violation in EPA's records, most of them paperwork.
Where it serves
Boise City
ZIP codes the system reported serving: 83704
Nearby utilities
- Veolia Water Idaho Boise City · same area
- Garden City Water and Sewer System Garden City · 6 mi · PFAS above limit
- Meridian Water Dept Meridian · 8 mi
- City of Nampa Nampa · 17 mi
- City of Caldwell Caldwell · 22 mi
- City of Twin Falls Twin Falls · 114 mi
Questions
Is Capitol Water Corp water safe to drink?
Capitol Water Corp had 3 health-based violations since 2016, all since resolved. EPA testing found PFAS above the 2024 federal limits, which systems must meet by 2029. Federal data can't tell you about your own pipes: lead comes from service lines and plumbing, so test your tap if your home was built before 1986. For the official word, read the utility's annual Consumer Confidence Report.
Does Capitol Water Corp water have PFAS?
Yes. EPA's 2023–2025 testing of Capitol Water Corp found 7 PFAS at least once. The highest entry-point averages were above the federal limit for PFOA and PFOS and PFNA: PFOA 5.8 ppt, PFOS 9.45 ppt, PFNA 37.5 ppt (limit 4 ppt for PFOA and PFOS, 10 ppt for the others).
What is the lead level in Capitol Water Corp water?
The most recent 90th-percentile lead result for Capitol Water Corp is 3 ppb, for the monitoring period that began Jan 2024 (still in progress). The federal action level is 15 ppb, falling to 10 ppb in November 2027. The 90th percentile means 9 in 10 homes sampled were at or below this number. Individual homes can be higher.
Check these numbers yourself
Every figure on this page comes from public EPA records. You don't have to take our word for it:
- EPA's own report for ID4010022: violations, enforcement and inspections, straight from EPA.
- EPA UCMR 5 data: the PFAS and lithium results (search the file for PWSID ID4010022).
- EPA SDWIS download: the lead results, population and violation records we use.
- The utility's annual water quality report (Consumer Confidence Report): ask Capitol Water Corp at (208) 375-0931, or see EPA's guide to finding it.
Found something that doesn't match? Tell us and we'll check it against EPA's records. How we check our data.
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.