Nitrate
Colonial Oak Water Company Inc.
Nitrate, a fertilizer chemical, frequently contaminates drinking water due to agricultural and urban runoff, and discharges from municipal wastewater treatment plants and septic tanks. Excessive nitrate in water can cause oxygen deprivation in infants and increase the risk of cancer. Click here to read more about nitrate.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2018 | 9.32 ppm | 30 | 30 | 0.400 ppm - 11.9 ppm |
| 2019 | 9.69 ppm | 29 | 29 | 1.60 ppm - 12.6 ppm |
| 2020 | 10.1 ppm | 28 | 28 | 7.60 ppm - 12.2 ppm |
| 2021 | 10.3 ppm | 30 | 30 | 8.30 ppm - 12.8 ppm |
| 2022 | 10.4 ppm | 28 | 28 | 8.30 ppm - 13.7 ppm |
| 2023 | 11.1 ppm | 32 | 32 | 9.20 ppm - 18.9 ppm |
ppm = parts per million
State, National, and Health Guidelines for Drinking Water
EWG Health Guideline: 0.14 ppm
The EWG health guideline of 0.14 parts per million, or ppm, for nitrate and nitrite is based on the equivalent health guideline for nitrate, as defined in a peer-reviewed scientific study by EWG. This guideline represents a one-in-one-million annual cancer risk level.
EPA Maximum Contaminant
Level (MCL): 10 ppm
The legal limit for nitrate, established in 1962, was developed to protect infants from acute methemoglobinemia, a life-threatening disorder of oxygen transport in the body. This limit does not fully protect against the risk of cancer and harm to the developing fetus.
ppm = parts per million
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2018-01-04 | CA2700534_005_005-201801041530 | 9.20 ppm |
| 2018-01-11 | CA2700534_006_006-201801111125 | 7.90 ppm |
| 2018-02-12 | CA2700534_001_001-201802121251 | 7.90 ppm |
| 2018-02-12 | CA2700534_005_005-201802121303 | 9.40 ppm |
| 2018-02-12 | CA2700534_003_003-201802121253 | 10.6 ppm |
| 2018-02-12 | CA2700534_004_004-201802121259 | 9.70 ppm |
| 2018-03-07 | CA2700534_005_005-201803071345 | 9.90 ppm |
| 2018-04-03 | CA2700534_005_005-201804030944 | 9.40 ppm |
| 2018-05-02 | CA2700534_001_001-201805021410 | 10.1 ppm |
| 2018-05-02 | CA2700534_003_003-201805021405 | 11.9 ppm |
| 2018-05-02 | CA2700534_004_004-201805021420 | 9.70 ppm |
| 2018-05-02 | CA2700534_005_005-201805021400 | 0.400 ppm |
| 2018-05-02 | CA2700534_006_006-201805021415 | 7.40 ppm |
| 2018-05-04 | CA2700534_001_001-201805041218 | 9.70 ppm |
| 2018-05-04 | CA2700534_005_005-201805041226 | 8.80 ppm |
| 2018-06-07 | CA2700534_005_005-201806071542 | 9.20 ppm |
| 2018-07-17 | CA2700534_005_005-201807171140 | 9.20 ppm |
| 2018-08-03 | CA2700534_004_004-201808031108 | 9.40 ppm |
| 2018-08-03 | CA2700534_003_003-201808031106 | 11.2 ppm |
| 2018-08-03 | CA2700534_006_006-201808031107 | 8.10 ppm |
| 2018-08-03 | CA2700534_005_005-201808031115 | 9.20 ppm |
| 2018-08-03 | CA2700534_001_001-201808031105 | 11.0 ppm |
| 2018-09-07 | CA2700534_005_005-201809071058 | 9.40 ppm |
| 2018-10-10 | CA2700534_005_005-201810101548 | 9.40 ppm |
| 2018-11-14 | CA2700534_005_005-201811141413 | 9.20 ppm |
| 2018-11-14 | CA2700534_001_001-201811141405 | 11.7 ppm |
| 2018-11-14 | CA2700534_004_004-201811141409 | 11.5 ppm |
| 2018-11-14 | CA2700534_003_003-201811141407 | 11.2 ppm |
| 2018-11-14 | CA2700534_006_006-201811141411 | 8.10 ppm |
| 2018-12-04 | CA2700534_005_005-201812041350 | 9.90 ppm |
| 2019-01-16 | CA2700534_005_005-201901161205 | 9.40 ppm |
| 2019-02-06 | CA2700534_003_003-201902061155 | 11.0 ppm |
| 2019-02-06 | CA2700534_004_004-201902061200 | 10.6 ppm |
| 2019-02-06 | CA2700534_005_005-201902061150 | 9.70 ppm |
| 2019-02-06 | CA2700534_006_006-201902061204 | 8.30 ppm |
| 2019-02-06 | CA2700534_001_001-201902061157 | 11.7 ppm |
| 2019-03-04 | CA2700534_005_005-201903041116 | 9.70 ppm |
| 2019-04-08 | CA2700534_005_005-201904081205 | 9.20 ppm |
| 2019-05-20 | CA2700534_006_006-201905201340 | 8.10 ppm |
| 2019-05-20 | CA2700534_001_001-201905201337 | 12.2 ppm |
| 2019-05-20 | CA2700534_003_003-201905201338 | 11.2 ppm |
| 2019-05-20 | CA2700534_004_004-201905201339 | 10.1 ppm |
| 2019-05-20 | CA2700534_005_005-201905201335 | 9.00 ppm |
| 2019-06-07 | CA2700534_005_005-201906071220 | 9.70 ppm |
| 2019-07-02 | CA2700534_005_005-201907021305 | 9.20 ppm |
| 2019-08-07 | CA2700534_005_005-201908071405 | 9.20 ppm |
| 2019-08-07 | CA2700534_001_001-201908071411 | 11.5 ppm |
| 2019-08-07 | CA2700534_004_004-201908071415 | 11.9 ppm |
| 2019-08-07 | CA2700534_006_006-201908071413 | 7.20 ppm |
| 2019-08-07 | CA2700534_003_003-201908071409 | 11.0 ppm |
| 2019-09-04 | CA2700534_005_005-201909041050 | 8.10 ppm |
| 2019-10-02 | CA2700534_005_005-201910021520 | 9.20 ppm |
| 2019-11-12 | CA2700534_004_004-201911121452 | 12.6 ppm |
| 2019-11-12 | CA2700534_001_001-201911121445 | 11.5 ppm |
| 2019-11-12 | CA2700534_003_003-201911121442 | 11.2 ppm |
| 2019-11-12 | CA2700534_005_005-201911121454 | 1.60 ppm |
| 2019-11-12 | CA2700534_006_006-201911121448 | 7.90 ppm |
| 2019-11-14 | CA2700534_005_005-201911141358 | 9.70 ppm |
| 2019-12-10 | CA2700534_005_005-201912101021 | 9.40 ppm |
| 2020-01-09 | CA2700534_005_005-202001091448 | 9.70 ppm |
| 2020-02-21 | CA2700534_001_001-202002211133 | 11.7 ppm |
| 2020-02-21 | CA2700534_006_006-202002211136 | 8.10 ppm |
| 2020-02-21 | CA2700534_005_005-202002211146 | 9.70 ppm |
| 2020-02-21 | CA2700534_003_003-202002211130 | 11.2 ppm |
| 2020-02-21 | CA2700534_004_004-202002211140 | 11.0 ppm |
| 2020-03-12 | CA2700534_005_005-202003120940 | 9.90 ppm |
| 2020-04-02 | CA2700534_005_005-202004021000 | 9.70 ppm |
| 2020-05-13 | CA2700534_003_003-202005131215 | 11.2 ppm |
| 2020-05-13 | CA2700534_005_005-202005131447 | 9.00 ppm |
| 2020-05-13 | CA2700534_001_001-202005131216 | 7.90 ppm |
| 2020-05-13 | CA2700534_004_004-202005131218 | 11.9 ppm |
| 2020-05-13 | CA2700534_006_006-202005131444 | 7.60 ppm |
| 2020-06-15 | CA2700534_005_005-202006151045 | 9.90 ppm |
| 2020-07-07 | CA2700534_005_005-202007071325 | 9.40 ppm |
| 2020-08-25 | CA2700534_005_005-202008251010 | 9.40 ppm |
| 2020-08-25 | CA2700534_001_001-202008250956 | 11.7 ppm |
| 2020-08-25 | CA2700534_003_003-202008250954 | 11.3 ppm |
| 2020-08-25 | CA2700534_004_004-202008250955 | 12.2 ppm |
| 2020-08-25 | CA2700534_006_006-202008250957 | 7.60 ppm |
| 2020-09-04 | CA2700534_005_005-202009041528 | 9.70 ppm |
| 2020-10-02 | CA2700534_005_005-202010021249 | 9.00 ppm |
| 2020-11-03 | CA2700534_006_006-202011031135 | 8.30 ppm |
| 2020-11-03 | CA2700534_004_004-202011031136 | 11.7 ppm |
| 2020-11-03 | CA2700534_001_001-202011031134 | 11.9 ppm |
| 2020-11-03 | CA2700534_005_005-202011031138 | 9.70 ppm |
| 2020-11-03 | CA2700534_003_003-202011031134 | 11.0 ppm |
| 2020-12-07 | CA2700534_005_005-202012070945 | 10.1 ppm |
| 2021-01-22 | CA2700534_005_005-202101221335 | 9.70 ppm |
| 2021-02-17 | CA2700534_005_005-202102171455 | 9.90 ppm |
| 2021-02-17 | CA2700534_001_001-202102171440 | 12.4 ppm |
| 2021-02-17 | CA2700534_003_003-202102171441 | 11.0 ppm |
| 2021-02-17 | CA2700534_006_006-202102171445 | 8.80 ppm |
| 2021-02-17 | CA2700534_004_004-202102171442 | 10.4 ppm |
| 2021-03-18 | CA2700534_005_005-202103181030 | 10.1 ppm |
| 2021-03-23 | CA2700534_005_005-202103230910 | 9.70 ppm |
| 2021-04-12 | CA2700534_005_005-202104121350 | 9.90 ppm |
| 2021-05-18 | CA2700534_004_004-202105181054 | 10.4 ppm |
| 2021-05-18 | CA2700534_005_005-202105181056 | 9.70 ppm |
| 2021-05-18 | CA2700534_006_006-202105181052 | 9.00 ppm |
| 2021-05-18 | CA2700534_001_001-202105181051 | 12.8 ppm |
| 2021-05-18 | CA2700534_003_003-202105181053 | 11.5 ppm |
| 2021-06-28 | CA2700534_005_005-202106281103 | 9.90 ppm |
| 2021-07-22 | CA2700534_005_005-202107221416 | 10.1 ppm |
| 2021-07-26 | CA2700534_005_005-202107261235 | 9.70 ppm |
| 2021-08-18 | CA2700534_001_001-202108181405 | 12.6 ppm |
| 2021-08-18 | CA2700534_003_003-202108181404 | 11.2 ppm |
| 2021-08-18 | CA2700534_004_004-202108181406 | 9.90 ppm |
| 2021-08-18 | CA2700534_005_005-202108181411 | 10.1 ppm |
| 2021-08-18 | CA2700534_006_006-202108181407 | 9.20 ppm |
| 2021-09-09 | CA2700534_005_005-202109091345 | 10.1 ppm |
| 2021-10-11 | CA2700534_005_005-202110111120 | 10.1 ppm |
| 2021-11-05 | CA2700534_001_001-202111051255 | 11.9 ppm |
| 2021-11-05 | CA2700534_006_006-202111051258 | 8.30 ppm |
| 2021-11-05 | CA2700534_004_004-202111051257 | 11.2 ppm |
| 2021-11-05 | CA2700534_005_005-202111051305 | 9.70 ppm |
| 2021-11-05 | CA2700534_003_003-202111051256 | 11.0 ppm |
| 2021-12-17 | CA2700534_005_005-202112171255 | 9.90 ppm |
| 2022-01-13 | CA2700534_005_005-202201131526 | 9.90 ppm |
| 2022-02-15 | CA2700534_005_005-202202151242 | 9.90 ppm |
| 2022-03-21 | CA2700534_003_003-202203211312 | 11.5 ppm |
| 2022-03-21 | CA2700534_005_005-202203211320 | 10.1 ppm |
| 2022-03-21 | CA2700534_004_004-202203211316 | 12.2 ppm |
| 2022-03-21 | CA2700534_001_001-202203211313 | 12.6 ppm |
| 2022-03-21 | CA2700534_006_006-202203211314 | 8.80 ppm |
| 2022-04-12 | CA2700534_005_005-202204120943 | 10.1 ppm |
| 2022-05-10 | CA2700534_001_001-202205101457 | 11.7 ppm |
| 2022-05-10 | CA2700534_004_004-202205101500 | 13.7 ppm |
| 2022-05-10 | CA2700534_003_003-202205101455 | 11.0 ppm |
| 2022-05-10 | CA2700534_005_005-202205101521 | 9.90 ppm |
| 2022-05-10 | CA2700534_006_006-202205101459 | 8.30 ppm |
| 2022-06-02 | CA2700534_005_005-202206021521 | 9.70 ppm |
| 2022-07-11 | CA2700534_005_005-202207111206 | 9.90 ppm |
| 2022-08-16 | CA2700534_006_006-202208161155 | 8.30 ppm |
| 2022-08-16 | CA2700534_001_001-202208161153 | 12.2 ppm |
| 2022-08-16 | CA2700534_004_004-202208161154 | 13.0 ppm |
| 2022-08-16 | CA2700534_003_003-202208161153 | 11.2 ppm |
| 2022-08-16 | CA2700534_005_005-202208161150 | 9.90 ppm |
| 2022-09-15 | CA2700534_005_005-202209151537 | 9.90 ppm |
| 2022-10-11 | CA2700534_005_005-202210111445 | 9.90 ppm |
| 2022-11-01 | CA2700534_001_001-202211011105 | 8.60 ppm |
| 2022-11-01 | CA2700534_003_003-202211011105 | 11.5 ppm |
| 2022-11-01 | CA2700534_004_004-202211011106 | 11.9 ppm |
| 2022-11-01 | CA2700534_006_006-202211011107 | 8.30 ppm |
| 2022-11-01 | CA2700534_005_005-202211011110 | 9.40 ppm |
| 2022-12-05 | CA2700534_005_005-202212051509 | 8.60 ppm |
| 2023-01-11 | CA2700534_005_005-202301111140 | 9.40 ppm |
| 2023-02-14 | CA2700534_004_004-202302141104 | 10.8 ppm |
| 2023-02-14 | CA2700534_005_005-202302141126 | 10.4 ppm |
| 2023-02-14 | CA2700534_001_001-202302141105 | 12.4 ppm |
| 2023-02-14 | CA2700534_003_003-202302141102 | 11.2 ppm |
| 2023-02-14 | CA2700534_006_006-202302141106 | 9.20 ppm |
| 2023-02-16 | CA2700534_005_005-202302160938 | 10.4 ppm |
| 2023-03-14 | CA2700534_005_005-202303141120 | 9.20 ppm |
| 2023-04-18 | CA2700534_005_005-202304181254 | 10.6 ppm |
| 2023-05-16 | CA2700534_004_004-202305161430 | 15.1 ppm |
| 2023-05-16 | CA2700534_001_001-202305161423 | 12.8 ppm |
| 2023-05-16 | CA2700534_003_003-202305161425 | 11.9 ppm |
| 2023-05-16 | CA2700534_005_005-202305161435 | 11.0 ppm |
| 2023-05-16 | CA2700534_006_006-202305161428 | 9.20 ppm |
| 2023-06-21 | CA2700534_005_005-202306211055 | 10.6 ppm |
| 2023-07-10 | CA2700534_005_005-202307101450 | 10.1 ppm |
| 2023-08-15 | CA2700534_003_003-202308151215 | 11.7 ppm |
| 2023-08-15 | CA2700534_004_004-202308151220 | 18.9 ppm |
| 2023-08-15 | CA2700534_005_005-202308151200 | 10.6 ppm |
| 2023-08-15 | CA2700534_006_006-202308151218 | 9.70 ppm |
| 2023-08-15 | CA2700534_001_001-202308151216 | 13.0 ppm |
| 2023-09-19 | CA2700534_005_005-202309191522 | 10.1 ppm |
| 2023-09-21 | CA2700534_005_005-202309211225 | 10.4 ppm |
| 2023-10-23 | CA2700534_005_005-202310231422 | 10.1 ppm |
| 2023-10-25 | CA2700534_005_005-202310251430 | 10.1 ppm |
| 2023-11-13 | CA2700534_001_001-202311131442 | 11.9 ppm |
| 2023-11-13 | CA2700534_005_005-202311131427 | 10.1 ppm |
| 2023-11-13 | CA2700534_003_003-202311131425 | 11.5 ppm |
| 2023-11-13 | CA2700534_004_004-202311131444 | 12.6 ppm |
| 2023-11-13 | CA2700534_006_006-202311131426 | 9.70 ppm |
| 2023-11-15 | CA2700534_005_005-202311151310 | 10.1 ppm |
| 2023-12-19 | CA2700534_005_005-202312191220 | 9.90 ppm |