Nitrite in Drinking Water in Ireland
Explore EPA Ireland monitoring records, listed exceedances and historical trends for Nitrite in public drinking-water supplies across Ireland.
Nitrite is a nitrogen compound distinct from nitrate.
- Latest monitoring year
- 2025
- Page updated
- September 2026
- Data available
- 2021, 2022, 2023, 2024, 2025
These are historical public-supply monitoring records, not a current water notice or a test of every household. Sampling locations can be outside the linked towns.
What do the latest results show?
The latest year is 2025. Results and listed exceedances are counted separately from their respective datasets.
- In 2025, 1,231 Nitrite monitoring results were recorded from 1,231 samples across 704 public water supplies.
- The separate EPA exceedance dataset lists 0 records across 0 schemes in 2025.
- There were 17 more monitoring results than in 2024 (1.4% more). This describes the volume of monitoring, not a change in water quality.
Nitrite at the tap and the Irish standard
Recorded results for 2025, with official requirements shown separately.
Irish drinking-water requirement
0.5 mg/l
As nitrite (NO₂), at the tap. Schedule 1 Note 11 sets 0.10 mg/l ex treatment works and [nitrate]/50 + [nitrite]/3 < 1.
This is separate guidance, not a test result for your own water. It does not reclassify historical records.
Official guidance checked 14 Sep 2026.
Monitoring coverage · 2025
- Numeric measurements
- 16
- EPA-listed exceedances
- 0
- Water supplies monitored
- 704
- First sample
- 03 Jan 2025
- Latest sample
- 16 Dec 2025
These are historical records, not the current status of your water. EPA-listed exceedances come from a separate dataset.
The selected source is Nitrite (at tap). Its 0.50 mg/l parametric value must not be confused with the separate 0.10 mg/l requirement for water leaving treatment works.
Monitoring measurement units are not verified, so these recorded values cannot be compared with the official standard. Units in the listed exceedance table are reproduced separately from that source.
How to read these results
Measurement coverage · 2021–2025
The imported monitoring records have no unit field. These are counts of recorded values, not concentrations or a comparison with the standard.
220 numeric records; 5,207 censored text records; 0 other text-only records; 210 records without a result value.
5,395 records have a non-empty text field, including records that also have a numeric value. This overlapping field count must not be added to the numeric total.
| Year | Numeric | Non-empty text field | Censored text | Other text only | No result value |
|---|---|---|---|---|---|
| 2021 | 71 | 948 | 877 | 0 | 2 |
| 2022 | 47 | 1,077 | 1,030 | 0 | 1 |
| 2023 | 16 | 1,058 | 1,047 | 0 | 101 |
| 2024 | 70 | 1,089 | 1,045 | 0 | 99 |
| 2025 | 16 | 1,223 | 1,208 | 0 | 7 |
Monitoring history 2021–2025
Monitoring volume and listed exceedances have separate scales. Select a year to inspect its figures.
Across this period, 5,637 results from 5,637 samples cover 740 distinct water supplies. Sample dates run from 05 Jan 2021 to 16 Dec 2025.
20251,231 results · 0 listed exceedances · 704 schemes monitored
Monitoring results — independent scale
EPA-listed exceedance records — independent scale
These are record counts, not an official EPA compliance rate. The number and selection of samples and monitored schemes can change between years.
There were 17 more monitoring results than in 2024 (1.4% more). This describes the volume of monitoring, not a change in water quality.
| Year | Results | Samples | Schemes monitored | Listed exceedances | Schemes with listed exceedances |
|---|---|---|---|---|---|
| 2021 | 950 | 950 | 592 | 1 | 1 |
| 2022 | 1,078 | 1,078 | 619 | 0 | 0 |
| 2023 | 1,164 | 1,164 | 642 | 0 | 0 |
| 2024 | 1,214 | 1,214 | 660 | 0 | 0 |
| 2025 | 1,231 | 1,231 | 704 | 0 | 0 |
EPA-listed Nitrite exceedances
1 listed records across 1 distinct schemes, 2021–2025. These are historical sample records, not a current assessment of each property in a supply zone.
Results and limits below are reproduced from the separate EPA exceedance dataset, with its own reported units. These units are not assigned to the wider monitoring dataset.
| Year | Records | Schemes | Lowest listed result | Highest listed result | Reported unit | Reported limit |
|---|---|---|---|---|---|---|
| 2021 | 1 | 1 | 1.02 | 1.02 | mg/l | 0.5 |
Show all 1 listed records 2021–2025 · newest first
| Date | Result | Reported unit | Reported limit | Water supply scheme | Scheme code |
|---|---|---|---|---|---|
| 19 Apr 2021 | 1.02 | mg/l | 0.5 | BARNDARRIG PUBLIC SUPPLY | 3400PUB1039 |
Places with mapped Nitrite monitoring data
Explore existing place reports with mapped Water Supply Zones containing Nitrite monitoring records in 2021–2025.
95 published places have at least one qualifying mapped zone. The 20 largest are listed below by Census 2022 population, not by Nitrite levels.
Places can share the same Water Supply Zone. These links do not represent independent city measurements; sampling locations may be outside the named Built Up Area. National totals above count each source record once.
DublinDublinCorkCorkLimerickLimerickGalwayGalwayWaterfordWaterfordDroghedaLouthDundalkLouthSwordsDublinNavanMeathBrayWicklowEnnisClareCarlowCarlowKilkennyKilkennyNaasKildareTraleeKerryNewbridgeKildareBalbrigganDublinPortlaoiseLaoisAthloneWestmeathMullingarWestmeath
View all places — the complete published place directory.
Tap and treatment-works requirements differ
The selected source is Nitrite (at tap). Its 0.50 mg/l parametric value must not be confused with the separate 0.10 mg/l requirement for water leaving treatment works.
Current water information for your address
For current supply information, check your Eircode with Uisce Éireann. Follow the notice for your address: a Boil Water Notice and a Do Not Consume Notice have different instructions. This historical report does not recommend boiling as a treatment for chemical parameters.
Frequently asked questions
What does this Nitrite report cover?
5,637 monitoring records across 5 available monitoring year(s): 2021, 2022, 2023, 2024, 2025. The selected source is Nitrite (at tap). National totals come directly from EPA records, not a sum of towns.
What is the Irish drinking-water requirement for Nitrite?
0.5 mg/l. As nitrite (NO₂), at the tap. Schedule 1 Note 11 sets 0.10 mg/l ex treatment works and [nitrate]/50 + [nitrite]/3 < 1.
Does this page include nitrite at the treatment works?
No. The canonical page currently maps only the source parameter Nitrite (at tap). It does not relabel tap samples as treatment-works samples.
Can I compare the recorded Nitrite values with the standard?
Monitoring unit metadata have not been verified in this import. Numeric and censored records are counted separately; no concentration median, maximum or compliance rate is inferred from them. Listed records keep the units supplied by the separate EPA exceedance dataset.
Does a place link give the current Nitrite result at my address?
No. It identifies a place with a mapped supply and historical monitoring. It is not a test of every property. Check current Uisce Éireann supply information using your Eircode.
Sources and methodology
- Monitoring data
- EPA Ireland: drinking-water monitoring data: public-supply monitoring results and the separate listed exceedance records, 2021–2025.
- Water testing
- Uisce Éireann: drinking water tests
- Counting
- Source records are counted once across schemes. A sample is identified by its scheme, sample ID and date. Listed exceedances are not inferred from numeric results.
- Interpretation
- Text and censored results are not converted to numbers. Missing values are not zero. Records do not establish conditions in an individual home or an official compliance rate.