Nitrate
North Wales Water Authority
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 | 1.48 ppm | 38 | 36 | ND - 4.01 ppm |
| 2019 | 1.39 ppm | 37 | 27 | ND - 4.36 ppm |
| 2020 | 1.31 ppm | 37 | 36 | ND - 4.09 ppm |
| 2021 | 1.45 ppm | 37 | 37 | 0.300 ppm - 4.16 ppm |
| 2022 | 1.23 ppm | 36 | 36 | 0.300 ppm - 3.91 ppm |
| 2023 | 1.22 ppm | 32 | 32 | 0.340 ppm - 3.82 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 |
|---|---|---|
| 2018-01-09 | 20180087 | 0.693 ppm |
| 2018-01-22 | 20180305 | 3.72 ppm |
| 2018-01-22 | 20180306 | 4.01 ppm |
| 2018-01-23 | 20180321 | 0.969 ppm |
| 2018-02-06 | 20180480 | 1.08 ppm |
| 2018-02-20 | 20180664 | 1.22 ppm |
| 2018-03-13 | 20180944 | 0.982 ppm |
| 2018-03-26 | 20181103 | 0.879 ppm |
| 2018-04-03 | 20181257 | 0.768 ppm |
| 2018-04-17 | 20181468 | 0.686 ppm |
| 2018-04-23 | 20181626 | 2.76 ppm |
| 2018-04-23 | 20181627 | 1.74 ppm |
| 2018-04-23 | 20181629 | 1.03 ppm |
| 2018-04-23 | 20181630 | ND |
| 2018-04-23 | 20181631 | 2.14 ppm |
| 2018-04-23 | 20181632 | 3.77 ppm |
| 2018-04-23 | 20181633 | 3.80 ppm |
| 2018-04-23 | 20181634 | 2.53 ppm |
| 2018-05-01 | 20181676 | 0.651 ppm |
| 2018-05-03 | 8052006-01 | ND |
| 2018-05-15 | 20181913 | 0.640 ppm |
| 2018-06-05 | 20182136 | 0.772 ppm |
| 2018-07-10 | 20182600 | 0.359 ppm |
| 2018-07-23 | 20182799 | 2.90 ppm |
| 2018-07-23 | 20182800 | 3.96 ppm |
| 2018-07-24 | 20182817 | 0.497 ppm |
| 2018-08-07 | 20182985 | 0.436 ppm |
| 2018-08-21 | 20183235 | 0.415 ppm |
| 2018-09-04 | 20183361 | 0.474 ppm |
| 2018-09-18 | 20183554 | 0.698 ppm |
| 2018-10-01 | 20183716 | 3.12 ppm |
| 2018-10-01 | 20183717 | 3.74 ppm |
| 2018-10-02 | 20183739 | 0.536 ppm |
| 2018-10-16 | 20183956 | 0.715 ppm |
| 2018-11-07 | 20184204 | 0.794 ppm |
| 2018-11-19 | 20184385 | 0.898 ppm |
| 2018-12-04 | 20184561 | 0.888 ppm |
| 2018-12-18 | 20184767 | 0.911 ppm |
| 2019-01-08 | 20190073 | 0.792 ppm |
| 2019-01-21 | 20190227 | 3.66 ppm |
| 2019-01-21 | 20190228 | 3.91 ppm |
| 2019-01-22 | 20190231 | 0.852 ppm |
| 2019-02-05 | 20190433 | 0.795 ppm |
| 2019-02-21 | 20190687 | 0.862 ppm |
| 2019-03-19 | 20191041 | 0.769 ppm |
| 2019-04-02 | 20191220 | 0.631 ppm |
| 2019-04-16 | 20191451 | 0.662 ppm |
| 2019-04-22 | 20191534 | 2.89 ppm |
| 2019-04-22 | 20191535 | 1.63 ppm |
| 2019-04-22 | 20191536 | ND |
| 2019-04-22 | 20191537 | 1.04 ppm |
| 2019-04-22 | 20191538 | 0.201 ppm |
| 2019-04-22 | 20191539 | 2.30 ppm |
| 2019-04-22 | 20191540 | 3.71 ppm |
| 2019-04-22 | 20191541 | 4.12 ppm |
| 2019-04-22 | 20191542 | 2.44 ppm |
| 2019-05-07 | 9052358-01 | ND |
| 2019-05-21 | 9054390-01 | ND |
| 2019-06-04 | 9061931-01 | ND |
| 2019-06-18 | 9064070-01 | ND |
| 2019-07-09 | 9073410-01 | ND |
| 2019-07-23 | 9075912-01 | ND |
| 2019-07-29 | 20192893 | 3.27 ppm |
| 2019-08-06 | 9083171-01 | 4.01 ppm |
| 2019-08-19 | 20193259 | 0.531 ppm |
| 2019-09-03 | 20193432 | 0.463 ppm |
| 2019-09-17 | 9093731-01 | ND |
| 2019-10-01 | 9101721-01 | ND |
| 2019-10-15 | 9103854-01 | ND |
| 2019-11-05 | 20194303 | 0.804 ppm |
| 2019-11-19 | 20194626 | 4.01 ppm |
| 2019-11-19 | 20194627 | 4.36 ppm |
| 2019-11-19 | 20194572 | 0.780 ppm |
| 2019-12-03 | 20194737 | 0.857 ppm |
| 2019-12-17 | 20194937 | 0.982 ppm |
| 2020-01-07 | 21348975.00 | 0.750 ppm |
| 2020-01-20 | 21504756.00 | 2.91 ppm |
| 2020-01-20 | 21504758.00 | 4.03 ppm |
| 2020-01-21 | 21504760.00 | 0.700 ppm |
| 2020-02-04 | 21505233.00 | 0.810 ppm |
| 2020-02-18 | 21669097.00 | 0.790 ppm |
| 2020-03-03 | 21669703.00 | 0.690 ppm |
| 2020-04-13 | 22025457.00 | 2.85 ppm |
| 2020-04-13 | 22025459.00 | 0.630 ppm |
| 2020-04-13 | 22025461.00 | ND |
| 2020-04-13 | 22025463.00 | 1.07 ppm |
| 2020-04-13 | 22025465.00 | 0.330 ppm |
| 2020-04-13 | 22025467.00 | 2.17 ppm |
| 2020-04-13 | 22025469.00 | 2.57 ppm |
| 2020-04-13 | 22025471.00 | 4.09 ppm |
| 2020-04-21 | 22025503.00 | 0.530 ppm |
| 2020-05-05 | 22026076.00 | 0.550 ppm |
| 2020-05-19 | 22217420.00 | 0.470 ppm |
| 2020-06-02 | 22217700.00 | 2.33 ppm |
| 2020-06-02 | 22217698.00 | 0.460 ppm |
| 2020-06-16 | 22418619.00 | 0.410 ppm |
| 2020-07-07 | 22419200.00 | 0.350 ppm |
| 2020-07-20 | 22609691.00 | 2.51 ppm |
| 2020-07-20 | 22609693.00 | 3.99 ppm |
| 2020-07-21 | 22609689.00 | 0.370 ppm |
| 2020-08-11 | 22801267.00 | 0.450 ppm |
| 2020-08-18 | 22801269.00 | 0.470 ppm |
| 2020-09-01 | 22801796.00 | 0.400 ppm |
| 2020-09-15 | 23001413.00 | 0.420 ppm |
| 2020-10-06 | 23184724.00 | 0.560 ppm |
| 2020-10-19 | 23184744.00 | 2.43 ppm |
| 2020-10-19 | 23184746.00 | 3.93 ppm |
| 2020-10-20 | 23184748.00 | 0.590 ppm |
| 2020-11-04 | 23185225.00 | 0.800 ppm |
| 2020-11-18 | 23364204.00 | 0.730 ppm |
| 2020-12-01 | 23364574.00 | 0.710 ppm |
| 2020-12-15 | 23539427.00 | 0.630 ppm |
| 2021-01-05 | 23714638.00 | 0.780 ppm |
| 2021-01-19 | 23714642.00 | 0.650 ppm |
| 2021-02-03 | 23715176.00 | 3.43 ppm |
| 2021-02-03 | 23715178.00 | 3.98 ppm |
| 2021-02-04 | 23715173.00 | 0.600 ppm |
| 2021-02-16 | 23890528.00 | 0.670 ppm |
| 2021-03-02 | 23890821.00 | 0.810 ppm |
| 2021-03-16 | 24062510.00 | 0.630 ppm |
| 2021-04-06 | 24062975.00 | 0.570 ppm |
| 2021-04-19 | 24249698.00 | 0.500 ppm |
| 2021-04-21 | 24249701.00 | 2.87 ppm |
| 2021-04-21 | 24249704.00 | 1.61 ppm |
| 2021-04-21 | 24249708.00 | 2.12 ppm |
| 2021-04-21 | 24249711.00 | 3.79 ppm |
| 2021-04-21 | 24249714.00 | 4.00 ppm |
| 2021-04-21 | 24249717.00 | 2.77 ppm |
| 2021-05-04 | 24440668.00 | 1.90 ppm |
| 2021-05-04 | 24250232.00 | 0.410 ppm |
| 2021-05-18 | 24440710.00 | 0.300 ppm |
| 2021-06-01 | 24441279.00 | 0.480 ppm |
| 2021-06-15 | 24640246.00 | 0.620 ppm |
| 2021-07-06 | 24640809.00 | 0.460 ppm |
| 2021-07-19 | 24831098.00 | 2.95 ppm |
| 2021-07-19 | 24831100.00 | 4.16 ppm |
| 2021-07-20 | 24831096.00 | 0.620 ppm |
| 2021-08-03 | 24831530.00 | 0.440 ppm |
| 2021-08-17 | 25024924.00 | 0.380 ppm |
| 2021-09-07 | 25025508.00 | 0.550 ppm |
| 2021-09-21 | 25222360.00 | 0.520 ppm |
| 2021-10-05 | 25222801.00 | 0.430 ppm |
| 2021-10-18 | 25406993.00 | 3.16 ppm |
| 2021-10-18 | 25406995.00 | 3.86 ppm |
| 2021-10-18 | 25406991.00 | 0.550 ppm |
| 2021-11-02 | 25407188.00 | 0.650 ppm |
| 2021-11-16 | 25589843.00 | 0.500 ppm |
| 2021-12-01 | 25589948.00 | 0.480 ppm |
| 2021-12-28 | 25766344.00 | 0.530 ppm |
| 2022-01-04 | 25766346.00 | 0.650 ppm |
| 2022-02-09 | 26119369.00 | 0.750 ppm |
| 2022-02-22 | 26119414.00 | 3.82 ppm |
| 2022-02-22 | 26119416.00 | 3.90 ppm |
| 2022-02-22 | 26119412.00 | 0.610 ppm |
| 2022-03-01 | 26289349.00 | 0.640 ppm |
| 2022-03-15 | 26289351.00 | 0.620 ppm |
| 2022-04-04 | 26289652.00 | 2.89 ppm |
| 2022-04-04 | 26289654.00 | 1.59 ppm |
| 2022-04-04 | 26289656.00 | 1.29 ppm |
| 2022-04-04 | 26289658.00 | 1.94 ppm |
| 2022-04-04 | 26289664.00 | 3.67 ppm |
| 2022-04-04 | 26289660.00 | 3.91 ppm |
| 2022-04-04 | 26289662.00 | 2.04 ppm |
| 2022-04-05 | 26289666.00 | 0.530 ppm |
| 2022-04-19 | 26466012.00 | 0.470 ppm |
| 2022-05-03 | 26466488.00 | 0.460 ppm |
| 2022-05-17 | 26650609.00 | 0.580 ppm |
| 2022-06-07 | 26651188.00 | 0.500 ppm |
| 2022-06-21 | 26844650.00 | 0.300 ppm |
| 2022-07-05 | 26845190.00 | 0.410 ppm |
| 2022-07-06 | 26845192.00 | 2.44 ppm |
| 2022-07-06 | 26845194.00 | 3.89 ppm |
| 2022-07-19 | 27039241.00 | 0.390 ppm |
| 2022-08-02 | 27039491.00 | 0.420 ppm |
| 2022-08-16 | 27235827.00 | 0.470 ppm |
| 2022-09-06 | 27236532.00 | 0.400 ppm |
| 2022-09-20 | 27442927.00 | 0.410 ppm |
| 2022-10-03 | 27443440.00 | 0.500 ppm |
| 2022-10-03 | 27443442.00 | 0.500 ppm |
| 2022-10-04 | 27443438.00 | 0.630 ppm |
| 2022-10-17 | 27643299.00 | 0.520 ppm |
| 2022-11-01 | 27643780.00 | 0.550 ppm |
| 2022-11-15 | 27824537.00 | 0.510 ppm |
| 2022-12-06 | 27825007.00 | 0.500 ppm |
| 2022-12-19 | 28000380.00 | 0.640 ppm |
| 2023-01-03 | 28174645.00 | 0.780 ppm |
| 2023-01-17 | 28174647.00 | 0.630 ppm |
| 2023-02-06 | 28175129.00 | 2.01 ppm |
| 2023-02-07 | 28175131.00 | 0.620 ppm |
| 2023-02-21 | 28351357.00 | 3.74 ppm |
| 2023-02-21 | 28351106.00 | 0.580 ppm |
| 2023-03-07 | 28351651.00 | 0.620 ppm |
| 2023-03-21 | 28523038.00 | 0.590 ppm |
| 2023-04-03 | 28704458.00 | 2.85 ppm |
| 2023-04-03 | 28704460.00 | 1.52 ppm |
| 2023-04-03 | 28704462.00 | 1.85 ppm |
| 2023-04-03 | 28704464.00 | 3.82 ppm |
| 2023-04-03 | 28704466.00 | 2.00 ppm |
| 2023-04-04 | 28704468.00 | 0.520 ppm |
| 2023-04-17 | 28704476.00 | 0.490 ppm |
| 2023-05-02 | 28704844.00 | 0.520 ppm |
| 2023-05-22 | 28901990.00 | 0.440 ppm |
| 2023-06-06 | 28902581.00 | 0.400 ppm |
| 2023-06-19 | 29110139.00 | 1.96 ppm |
| 2023-06-19 | 29110137.00 | 0.340 ppm |
| 2023-07-10 | 29303745.00 | 3.82 ppm |
| 2023-07-11 | 29303747.00 | 0.400 ppm |
| 2023-07-25 | 29303751.00 | 0.380 ppm |
| 2023-08-08 | 29304457.00 | 0.530 ppm |
| 2023-08-22 | 29499556.00 | 0.440 ppm |
| 2023-09-12 | 29701896.00 | 0.620 ppm |
| 2023-10-02 | 29702361.00 | 3.67 ppm |
| 2023-10-03 | 29702363.00 | 0.700 ppm |
| 2023-10-17 | 29888455.00 | 0.620 ppm |
| 2023-11-13 | 30073017.00 | 0.510 ppm |
| 2023-12-05 | 30073584.00 | 0.490 ppm |
| 2023-12-18 | 30247652.00 | 0.420 ppm |