01The verdict: is Sentinel water safe?
Sentinel's tap water meets most EPA standards but has areas that warrant attention. With a grade of A (93.4/100), some contaminant levels or compliance issues suggest that residents may benefit from additional filtration. The city's 1 water system serves approximately 859 residents using groundwater (wells).
1 unresolved violation on record
EPA records show an open compliance item for this system. Most are administrative, but unresolved items are worth watching.
See what was cited ↓Lead is well under the limit
90th-percentile lead is 0.6 ppb — beneath the 15 ppb federal action level and under the 5 ppb watch threshold.
See the trend ↓2 violations in the last five years
Recent compliance history is the best predictor of future problems — the year-by-year record is below.
See the record ↓Sentinel's drinking water received a grade of A (93.4 out of 100), indicating excellent water quality. The city's 1 water system serves approximately 859 residents using purchased ground water.
Lead levels were measured at 0.6 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 11 violations on record, including 1 health-based violation. 1 remains unresolved.
Sentinel ranks #6 out of 357 cities in Oklahoma for water quality, placing it one of the best in the state. Sentinel purchases its water from a regional wholesaler, meaning quality depends on both the supplier's treatment and the local distribution system's condition. As a small community water system, Sentinel may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
02What's in Sentinel's water
Every contaminant flagged in Sentinel, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 0.6 | 15 | ppb | Inorganic | Safe |
Cities ranked by 90th-percentile lead PF PFAS in Oklahoma
Cities ranked by compounds detected Cu Copper in Oklahoma
Cities ranked by 90th-percentile copper
03Sentinel's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 11 violations on record, including 1 health-based violation. 1 remains unresolved.
9 of the last ten years were clean. The numbered years had EPA violations — red when any were health-based, amber when they were paperwork or missed-testing issues.
▼ Down 6.4 ppb since 1993. Latest reading: 0.64 ppb (2024) — 4% of the action level. Sampled at higher-risk homes (90th percentile).
04Where Sentinel's water comes from
Sentinel purchases its water supply from a regional wholesale provider rather than treating raw water directly.
Purchased Groundwater
Water is bought from a regional wholesaler; quality starts at the supplier's intake and treatment.
Wholesale supplier
Primary treatment happens at the wholesaler; the local utility maintains disinfectant residual in its pipes.
1 system
1 water system, operated under local government ownership.
859 people
Residents served across Sentinel's service area.
Water quality depends on both the wholesaler's treatment standards and the condition of Sentinel's local distribution pipes and storage facilities. Purchased water systems are common in suburban areas and smaller communities that lack the infrastructure for independent treatment. The system is operated by local government ownership and serves approximately 859 people through 1 water system.
| System name | PWSID | Population | Source |
|---|---|---|---|
| SENTINEL PWS | OK3007505 | 859 | Purchased Groundwater |
05Pressure on Sentinel's watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Flood & storm history
3 federal disaster declarations on record for Washita County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
Drought
Washita County is in D4 (exceptional drought) per the U.S. Drought Monitor (week of Jul 2026). Drought can raise disinfection-byproduct levels and taste/odor issues as utilities draw from lower reservoirs.
06How Sentinel compares
Scores for nearby Oklahoma cities on one line, with the average marked.
dashed line = Oklahoma average (45/100)
Sentinel scores 93.4/100 — above the Oklahoma average of 45/100. It outscores 10 of 10 nearby cities. Full Oklahoma rankings →
38.6 / 100DTulsa, OK
48.5 / 100FBroken Arrow, OK
43.9 / 100FNorman, OK
38.4 / 100FLawton, OK
44.4 / 100FEdmond, OK
34.9 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in Sentinel's water — not generic advice.
A basic carbon filter still helps
Sentinel's water meets federal standards, but a simple carbon filter improves taste and adds a margin of safety against short-term issues.
Compare tested filters →Read your utility's annual report
Every utility must publish a yearly Consumer Confidence Report with its own testing results. It pairs well with the independent data on this page.
How to read a CCR →Watch for Sentinel alerts
This area has a history of flood declarations — after severe weather, watch for boil-water advisories from the utility, and check the live alerts on this page.
All water alerts →Frequently asked questions
Is Sentinel, OK tap water safe to drink?
Sentinel's water quality earned a grade of A (93.4/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #6 out of 357 cities tested in Oklahoma.
What contaminants are in Sentinel's water?
Lead was measured at 0.6 ppb (90th percentile). 11 violations are on record.
How is Sentinel's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Sentinel?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Sentinel's water come from?
Sentinel's water is sourced from Purchased ground water. The city has 1 water system serving approximately 859 residents.
What health violations has Sentinel's water system had?
Sentinel has 1 health-based violation on record. The most recent violation was recorded in August 2021. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 1 violation remains unresolved.
Is Sentinel's groundwater at risk of contamination?
Sentinel uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 11 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Sentinel's water compare to other cities?
Sentinel ranks #6 out of 357 cities in Oklahoma (better than 98% of state cities) and #856 out of 15382 cities nationally (94th percentile). The grade of A reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Sentinel's small water system affect quality?
Sentinel's system serves approximately 859 residents. Small community water systems (under 3,300 people) may have fewer financial resources for infrastructure upgrades and advanced treatment technologies. However, they are held to the same EPA drinking water standards as larger systems. This system has 11 violations on record.