The Oasis at Grandfield

What EPA’s and Florida’s records show in this utility’s water: nitrate, arsenic and other regulated chemicals; lead and copper; and violations since 2016, with the certification that handles each result.

Serves: 48 people
Connections: 24
Water source: Groundwater
Based in: Thonotosassa, FL
County: Hillsborough
Owner: Private

The ZIP code it serves

33592

The short answer

Nothing in EPA’s and Florida’s records for this utility is above a health goal. That covers nitrate, arsenic and other regulated chemicals, plus lead and copper, not everything. No health-based violations on file since 2016.

What was found

Nitrate, haloacetic acids (HAA5), total trihalomethanes (TTHM), fluoride, chromium (total), arsenic and uranium: Florida’s own results, samples taken from Oct. 6, 2020 to Nov. 20, 2024, with EPA’s 2012 to 2019 file for earlier years.

Below EPA’s limits5

Nitrate

Comes from the source

Below EPA’s limits

9.4ppm

Highest sample; found in 11 of 11

2024 average: 6.8 ppm

The highest sample, in 2022, was 9.4 ppm, below EPA’s legal limit of 10 ppm. In 2024, the latest year on file, its five samples averaged 6.8 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 9.7 ppm, in 2012.

What handles it

NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

34.5ppb

Highest yearly average, 2021 to 2024

2024, one sample: 15.2 ppb

Averaged by year, the highest was 34.5 ppb, in 2021, below EPA’s legal limit of 60 ppb. In 2024, the latest year on file, its one sample was 15.2 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 19.3 ppb, in 2018.

What handles it

No certification claim covers this compound yet.

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

35.1ppb

Highest yearly average, 2021 to 2024

2024, one sample: 28.6 ppb

Averaged by year, the highest was 35.1 ppb, in 2021, below EPA’s legal limit of 80 ppb. In 2024, the latest year on file, its one sample was 28.6 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 11.7 ppb, in 2018.

What handles it

NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.3ppm

Highest yearly average, 2021 to 2024

2024 average: 0.13 ppm

Averaged by year, the highest was 0.3 ppm, in 2021, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.6 ppm. In 2024, the latest year on file, its three samples averaged 0.13 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.19 ppm, in 2015.

What handles it

NSF/ANSI 58 look for “Fluoride Reduction”
NSF/ANSI 53 look for “Fluoride”

Chromium (total)

Comes from the source

Below EPA’s limits

0.6ppb

Highest yearly average, 2021 to 2024

2024: not found

Averaged by year, the highest was 0.6 ppb, in 2021, below EPA’s legal limit of 100 ppb. In 2024, the latest year on file, it wasn’t found in its one sample. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.6 ppb, in 2015.

What handles it

NSF/ANSI 58 look for “Chromium (Hexavalent) Reduction”
NSF/ANSI 53 look for “Chromium Reduction”

3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.

Arsenic
Lead
Uranium

Violations since 2016

No health-based violations on file with EPA since 2016.

What this report can’t tell you

Everything else. Nitrate, haloacetic acids (HAA5), total trihalomethanes (TTHM), fluoride, chromium (total), arsenic and uranium results here are Florida’s own from 2020 on, with EPA’s national file for 2012 to 2019. The Oasis at Grandfield’s own annual report, which it must send you every year, has the contaminants this page does not show.
Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.
What it means for your health. This page reports what the records show and EPA’s limits and goals; it is not medical advice. If you are worried about a health effect, talk to a doctor or your local health department.
Anything after the latest data. SDWIS data is from 2026 Q3; UCMR 5 didn’t sample this utility; Florida’s results run from Oct. 6, 2020 to Nov. 20, 2024.

Testing your own tap

The Oasis at Grandfield’s results are for the water it sends out. What your own service line, solder and fixtures add shows up only in a test of your tap, by a lab Florida certifies.

The 3 labs Florida certifies closest to the area The Oasis at Grandfield serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

Advanced Environmental Laboratories, Inc. - Tampa
Tampa, FL · about 13 miles
Certified for bacteria, lead and copper, minerals and other inorganics, organic chemicals, disinfection byproducts
(813) 630-9616
Hillsborough County Environmental Laboratory
Tampa, FL · about 13 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics
(813) 272-5977
KNL Environmental Testing
Tampa, FL · about 14 miles
Certified for bacteria, radioactivity
(813) 229-2879

Florida Department of Health Bureau of Public Health Laboratories: Coliform and E. coli testing for private wells at the Jacksonville and Miami labs. Collection kits come from your county health department, and the sample has to reach the lab on ice the same day it is collected. $40 for private testing through the state lab. Well Water Testing, Florida Department of Health.

All 212 certified labs for Florida