{
  "url": "https://openlegislation.uk/bathing-water-regulations-2013/schedule-5/paragraph-2",
  "json_url": "https://openlegislation.uk/bathing-water-regulations-2013/schedule-5/paragraph-2.json",
  "legislation": "uksi/2013/1675",
  "legislation_title": "The Bathing Water Regulations 2013",
  "legislation_url": "https://openlegislation.uk/bathing-water-regulations-2013",
  "path": "schedule/5/paragraph/2",
  "kind": "paragraph",
  "number": "2",
  "heading": "Methodology",
  "text": "(1) In this Schedule, “percentile value” is based on a percentile evaluation of the log10 normal probability density function of microbiological data used for the assessment under regulation 10.\n(2) The appropriate agency must derive a percentile value as follows—\n(a) take the log10 value of all bacterial concentrations in the data sequence to be evaluated or, if a zero value is obtained, take the log10 value of the minimum detection limit of the analytical method used;\n(b) calculate the arithmetic mean (“μ”) of the log10 values taken under paragraph (a);\n(c) calculate the standard deviation (“σ”) of the log10 values taken under paragraph (a);\n(d) derive the upper 90-percentile point of the data probability density function from the following equation: upper 90-percentile = antilog (μ + 1.282 σ); and\n(e) derive the upper 95-percentile point of the data probability density function from the following equation: upper 95-percentile = antilog (µ + 1.645 σ).",
  "extent": null,
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "F",
      "label": "F1",
      "text": "Sch. 5 para. 2(2)(e): formula substituted (21.11.2025 for E., 1.4.2026 for W.) by The Bathing Water (Amendment) (England and Wales) Regulations 2025 (S.I. 2025/1129), regs. 1(2)(3), 12"
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/uksi/2013/1675/schedule/5/paragraph/2",
    "retrieved_at": "2026-10-29T00:48:40.853645+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}