E. coli in Drinking Water in Ireland
Explore EPA Ireland monitoring records, listed exceedances and historical trends for E. coli in public drinking-water supplies across Ireland.
E. coli is a type of bacterium. Its presence in drinking water is used as an indicator of faecal contamination.
- Latest monitoring year
- 2025
- Page updated
- September 2026
- Data available
- 2021, 2022, 2023, 2024, 2025
Monitoring records apply to public water supplies and their sampling locations. They do not test every household and cannot establish the current condition of your own tap water.
What do the latest results show?
The latest year is 2025. Results and listed exceedances are counted separately from their respective datasets.
- In 2025, 8,332 E. coli monitoring results were recorded from 8,332 samples across 711 public water supplies.
- The separate EPA exceedance dataset lists 11 records across 10 schemes in 2025.
- There were 430 more monitoring results than in 2024 (5.4% more). This describes the volume of monitoring, not a change in water quality.
E. coli levels and Irish standard
Recorded results for 2025, with official requirements shown separately.
Official Irish drinking-water standard
0 per 100 ml
Public piped drinking-water standard, not a test of an individual home.
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
- 8,233
- EPA-listed exceedances
- 11
- Water supplies monitored
- 711
- First sample
- 02 Jan 2025
- Latest sample
- 22 Dec 2025
These are historical records, not the current status of your water. EPA-listed exceedances come from a separate dataset.
Only E. coli records are included; Coliform Bacteria is a separate parameter.
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
How the 2025 results are recorded
- Numeric value recorded as zero
- 8,222
- Positive numeric value
- 11
- Censored text result
- 2
- Other text-only result
- 0
- No recorded result value
- 97
Most numeric records are zero, so this page shows record counts rather than a median or maximum. Censored values are not converted to numbers; missing values are not zero. Listed exceedances come only from the separate EPA dataset, not this classification.
Censored values retained exactly as reported: <1.
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.
40,325 numeric records; 2 censored text records; 67 other text-only records; 392 records without a result value.
19,923 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 | 8,234 | 4,055 | 0 | 67 | 0 |
| 2022 | 8,259 | 3,558 | 0 | 0 | 0 |
| 2023 | 7,900 | 4,241 | 0 | 0 | 92 |
| 2024 | 7,699 | 4,241 | 0 | 0 | 203 |
| 2025 | 8,233 | 3,828 | 2 | 0 | 97 |
Monitoring history 2021–2025
Monitoring volume and listed exceedances have separate scales. Select a year to inspect its figures.
Across this period, 40,786 results from 40,786 samples cover 757 distinct water supplies. Sample dates run from 04 Jan 2021 to 22 Dec 2025.
20258,332 results · 11 listed exceedances · 711 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 430 more monitoring results than in 2024 (5.4% 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 | 8,301 | 8,301 | 753 | 4 | 4 |
| 2022 | 8,259 | 8,259 | 734 | 1 | 1 |
| 2023 | 7,992 | 7,992 | 726 | 4 | 4 |
| 2024 | 7,902 | 7,902 | 719 | 5 | 5 |
| 2025 | 8,332 | 8,332 | 711 | 11 | 10 |
EPA-listed E. coli exceedances
25 listed records across 23 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 | 4 | 4 | 1 | 6 | 100ml | 0 |
| 2022 | 1 | 1 | 1 | 1 | 100ml | 0 |
| 2023 | 4 | 4 | 1 | 2 | 100ml | 0 |
| 2024 | 5 | 5 | 1 | 101 | 100ml | 0 |
| 2025 | 11 | 10 | 1 | 109 | 100ml | 0 |
Show all 25 listed records 2021–2025 · newest first
| Date | Result | Reported unit | Reported limit | Water supply scheme | Scheme code |
|---|---|---|---|---|---|
| 12 Dec 2025 | 1 | 100ml | 0 | Dursey Island | 0500PUB4207 |
| 09 Oct 2025 | 109 | 100ml | 0 | Shannon/Sixmilebridge RWSS | 0300PUB1040 |
| 09 Oct 2025 | 2 | 100ml | 0 | Shannon/Sixmilebridge RWSS | 0300PUB1040 |
| 18 Sep 2025 | 100 | 100ml | 0 | Ballinkillen | 0100PUB1166 |
| 08 Aug 2025 | 3 | 100ml | 0 | Bagenalstown | 0100PUB1161 |
| 31 Jul 2025 | 1 | 100ml | 0 | Kinvara PWS | 1200PUB1034 |
| 31 Jul 2025 | 1 | 100ml | 0 | LOUGH MASK RWSS | 2200PUB1032 |
| 21 Jul 2025 | 100 | 100ml | 0 | Nenagh RWSS | 2800PUB1008 |
| 16 Jul 2025 | 1 | 100ml | 0 | ARRANMORE ISLAND | 0600PUB1061 |
| 23 Jun 2025 | 1 | 100ml | 0 | Cullen | 0500PUB2206 |
| 13 Jun 2025 | 1 | 100ml | 0 | LONGFORD CENTRAL | 2000PUB1010 |
| 15 Oct 2024 | 9 | 100ml | 0 | Inishmore - Oghill | 1200PUB1026 |
| 07 Oct 2024 | 101 | 100ml | 0 | Ballyvadonna | 0500PUB1223 |
| 26 Aug 2024 | 1 | 100ml | 0 | GRANARD | 2000PUB1006 |
| 22 Apr 2024 | 11 | 100ml | 0 | LERWSS | 2400PUB1001 |
| 29 Mar 2024 | 25 | 100ml | 0 | Ennis PWS | 0300PUB1009 |
| 04 Dec 2023 | 1 | 100ml | 0 | KILMACANOGUE PUBLIC SUPPLY | 3400PUB1009 |
| 30 Nov 2023 | 1 | 100ml | 0 | KILLAVANEY PUBLIC SUPPLY (TINAHELY) | 3400PUB1072 |
| 02 Oct 2023 | 2 | 100ml | 0 | Boyle Regional | 2600PUB1027 |
| 12 Sep 2023 | 1 | 100ml | 0 | Currenree | 0100PUB1177 |
| 19 Jul 2022 | 1 | 100ml | 0 | Cork City Water Supply | 0400PUB1001 |
| 06 Sep 2021 | 1 | 100ml | 0 | Ballinasloe Public Supply | 1200PUB1004 |
| 28 Jul 2021 | 1 | 100ml | 0 | Dunkerrin PWS | 2500PUB1007 |
| 15 Jun 2021 | 1 | 100ml | 0 | Cork City Water Supply | 0400PUB1001 |
| 17 May 2021 | 6 | 100ml | 0 | Camross PWS | 1600PUB0082 |
Places with mapped E. coli monitoring data
Explore existing place reports with mapped Water Supply Zones containing E. coli 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 E. coli 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.
What does E. coli in drinking water mean?
E. coli, short for Escherichia coli, is a bacterium associated with the intestines of humans and animals.
EPA explains that detecting E. coli can indicate problems with disinfection or contamination entering the distribution system after treatment. A detection therefore needs investigation to establish the cause and appropriate action.
What causes E. coli in drinking water?
Uisce Éireann identifies several possible routes. These are general explanations, not diagnoses of the historical records on this page.
- Contamination of the source water.
- Contamination entering the distribution network.
- Burst mains or other network incidents.
- Problems removing or inactivating bacteria during treatment and disinfection.
Health and current water notices
Some E. coli strains can cause illness. WaterCheck Ireland does not provide medical advice. This page presents historical monitoring data and is not a live safety service. Check your Eircode with Uisce Éireann for current supply information and follow any notice affecting your address.
Frequently asked questions
What is E. coli in water?
Escherichia coli is a bacterium. Its presence in drinking water is an indicator of faecal contamination.
What is the E. coli limit in drinking water in Ireland?
The Irish standard for public drinking-water supplies is 0 per 100 ml. This is the official standard, not a statement about your current tap water.
What causes E. coli in drinking water?
Possible causes include source contamination, network incidents and failures of treatment or disinfection.
Can you get E. coli from contaminated water?
Yes. Some strains can cause illness if contaminated water is swallowed. Follow official advice for your supply.
Does boiling water help during an E. coli contamination event?
During a Boil Water Notice, follow Uisce Éireann's instructions to boil and cool water before use. A Do Not Consume Notice has different instructions: do not assume boiling makes that water suitable for consumption.
How is E. coli tested in drinking water?
Water samples are examined using microbiological methods. The Irish regulations specify reference methods for E. coli testing, including EN ISO 9308-1 and EN ISO 9308-2.
What happens after an E. coli exceedance in Ireland?
Uisce Éireann investigates, notifies EPA and consults the HSE on public-health action. Customers are notified when a water notice is required.
Does an E. coli exceedance mean my own tap water is contaminated?
A historical record is evidence about a particular sample, not a current result for every tap. Check Uisce Éireann's current information for your address and follow any water notice.
Sources and methodology
- Monitoring data
- Environmental Protection Agency (EPA), Ireland: public-supply monitoring results and the separate listed exceedance records, 2021–2025.
- Water testing
- Uisce Éireann: drinking water tests
- Irish standard
- European Union (Drinking Water) Regulations 2023
- 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.