Nitrates in the aquifer

TL;DR

On 13 February 2026 MaltaToday reported on a peer-reviewed study of nitrate in Malta’s groundwater. The article quotes the study: “the highest concentrations of nitrate are observed in the eastern areas of the MSLA, ranging from 100 to 200 mg/L”, and adds that this is “two to four times higher than the EU safety limit of 50 mg/L”. We checked the arithmetic and tested the picture against the Commission’s own review of Malta’s monitoring data.

1. The arithmetic and the limit are right. 100 and 200 mg/L are two and four times 50 mg/L, the nitrate limit in the Nitrates Directive and the drinking-water standard.
2. The picture is confirmed by independent monitoring. The Commission’s 2020–2023 review of Malta’s Energy and Water Agency data finds 30 of 44 groundwater monitoring points (68.2%) with an average of 50 mg/L or more, up from 63.6% in 2016–2019.
3. The 100–200 mg/L figure matches the research team’s own earlier abstract. A 2025 EGU abstract by the same group gives 75–200 mg/L for groundwater under potato and forage fields in the central and eastern areas, and 25–100 mg/L in the regional aquifer under the north-western perched aquifer.
4. We could not read the paper’s full text. The sentence is therefore a second-hand quotation (via MaltaToday). Independent data do not give the eastern aquifer’s range separately.
5. Verdict: largely supported (moderate confidence). The figures are the study’s and the direction is confirmed; the exact eastern range rests on a quotation we could not check in the paper.

1. Supported
2. Largely supported
3. Not substantiated
4. Misleading
5. Contradicted

IN THIS REPORT

1 The claim and what we could verify

The claim record came from a MaltaToday article by James Debono, “Potatoes and intensive farming: A slow-moving threat to Malta’s groundwater”, 13 February 2026 [1]. We read it on 5 October 2026. The relevant paragraph says: “In the eastern areas of the main aquifer, the report notes: ‘Specifically, the highest concentrations of nitrate are observed in the eastern areas of the MSLA, ranging from 100 to 200 mg/L.’ This is two to four times higher than the EU safety limit of 50 mg/L.” The words inside quotation marks are the paper’s; the comparison with the limit is the outlet’s. The paper is Laudi, Dahan, Sapiano, Schembri, Galea, Busuttil, Mangion and Turkeltaub (2026), Journal of Hydrology: Regional Studies 64:103162 [2].

2 Method

Question. Is the quoted range reported accurately, is the comparison with the EU limit correct, and does independent monitoring agree with the picture?

Evidence. We transcribed the Commission’s figures into data/cc-047/, with source and retrieval date, and ran tools/cc-047-report/calc.py to test the arithmetic (multiples of 50 mg/L; shares times 44 stations give whole numbers; depth classes add up to 30 points). We compared the ranges in the team’s 2025 abstract with the 2026 quotation.

Grades. Laudi et al. (2026): B (observational study, monitoring network). Commission fiche: C (official statistics from national reporting). MaltaToday: D as evidence, used only as the locator. Verdicts follow the scale in Appendix A.

3 What the data show

Thirty points (68.2%) average 50 mg/L or more, six (13.6%) are at 40–49.99 mg/L, six at 25–39.99 and two below 25. The share at 50 or more rose from 63.6% (28 points) in 2016–2019. The Commission counts 35 nitrate pollution hotspots (79.5% of points) and notes that among points already at 50 or more, 88.9% were rising. The highest share is among shallow (5–15 m) wells at 83.3%. Whole-island averages per station are not published, so the Commission data cannot confirm “100–200 mg/L” for the eastern aquifer; they confirm that exceedance is the norm, not the exception.

4 Where the evidence points different ways

5 Testing the claim

6 Verdict and requests for evidence

Why. The arithmetic is right, the limit is the right one, and the Commission’s review of Malta’s own monitoring shows exceedance at most points. Why not Supported. The central sentence is a second-hand quotation, and no independent dataset gives the eastern aquifer’s range. What this verdict does not say. It does not say that the aquifer water reaching taps exceeds 50 mg/L: public supply is blended and treated, and we did not test tap-water data.

Evidence we are asking for

• From the Energy and Water Agency: station-level nitrate data for the eastern Mean Sea Level Aquifer, 2020–2025.
• From the authors or the journal: the paper’s page for the 100–200 mg/L sentence (open access).

7 Limitations

• We could not read the full text of Laudi et al. (2026); ScienceDirect refuses scripted access. The quoted sentence is second-hand, and the 2025 abstract is a conference abstract, not peer-reviewed in the same way.
• The Commission figures are per-station averages of annual means; they do not give an aquifer-wide mean.
• The study did not assess animal husbandry, which MaltaToday notes is a major nitrate source.
• We did not test whether groundwater levels translate to drinking-water levels.

References

1. [1] Debono J. (13 February 2026). Potatoes and intensive farming: A slow-moving threat to Malta’s groundwater. MaltaToday. https://www.maltatoday.com.mt/news/national/139611/potatoes_and_intensive_farming_a_slowmoving_threat_to_maltas_groundwater
2. [2] Laudi L., Dahan O., Sapiano M., Schembri M., Galea L., Busuttil E., Mangion J. & Turkeltaub T. (2026). Tracing nitrate fate in Malta’s hydrogeological system using an intensive vadose-groundwater monitoring network. Journal of Hydrology: Regional Studies 64:103162. doi:10.1016/j.ejrh.2026.103162. ◆ (abstract only). https://doi.org/10.1016/j.ejrh.2026.103162
3. [3] Laudi L., Dahan O., Sapiano M., Schembri M. & Turkeltaub T. (2025). Using vadose zone data to determine agricultural impact on groundwater pollution. EGU General Assembly abstract EGU25-13344. doi:10.5194/egusphere-egu25-13344. https://doi.org/10.5194/egusphere-egu25-13344
4. [4] European Commission (2026). Member State country fiche, Malta, on the implementation of Directive 91/676/EEC 2020–2023, SWD(2026) 232 final, Part 20/27 (Council doc. 12018/26 ADD 19). https://data.consilium.europa.eu/doc/document/ST-12018-2026-ADD-19/en/pdf
5. [5] MiŻien. Data and calculation: data/cc-047/; tools/cc-047-report/calc.py.

Appendix A: series standards and verdict scale

Every investigation in this series follows the same rules so that verdicts are comparable and challengeable.

Confidence

High: multiple independent lines of evidence agree. Moderate: evidence is relevant but incomplete or indirect. Low: evidence is thin, second-hand or conflicting.

Evidence grades

A experiment · B observational study with a control or gradient · C review, guidance or official statistics · D assertion or anecdote. ◆ marks a source known only second-hand.

Standards

• Quote the speaker, not the headline, with outlet and date, and link the original where possible.
• Separate the claim from the evidence offered for it, and say who made which statement.
• Grade the evidence and show differing views side by side where the evidence is unsettled.
• State what we could not access or verify, and what would change the verdict either way.
• Ask for the missing evidence in specific, answerable requests.
• Offer a right of reply where a check finds a claim Not substantiated, Misleading or Contradicted (or a pledge Not measurable, Off track or Missed), before wider circulation, and append responses.
• Correct errors openly with a version number and change log.
• Whistle-blow only on evidence: a verdict of Misleading or Contradicted requires documents or data that can be shown, not inference.
• Check every side. Government, opposition, NGOs and developers are held to the same standard.

Appendix B: revision log