{
  "url": "https://openlegislation.uk/private-water-supplies-wales-regulations-2017/schedule-4/part-2",
  "json_url": "https://openlegislation.uk/private-water-supplies-wales-regulations-2017/schedule-4/part-2.json",
  "legislation": "wsi/2017/1041",
  "legislation_title": "The Private Water Supplies (Wales) Regulations 2017",
  "legislation_url": "https://openlegislation.uk/private-water-supplies-wales-regulations-2017",
  "path": "schedule/4/part/2",
  "kind": "part",
  "number": "2",
  "heading": "Analytical methods",
  "text": "Table 1\nPrescribed methods of analysis for microbiological parameters\nParameter\nMethod\nEscherichia coli (E. coli)\nEN ISO 9308-1 or EN ISO 9308-2\nEnterococci\nEN ISO 7899-2\nPseudomonas aeruginosa\nEN-ISO 16266\nColony count 22°C — enumeration of culturable microorganisms\nEN ISO 6222\nColony count 36°C — enumeration of culturable microorganisms\nEN ISO 6222\nClostridium perfringens (including spores)\nEN ISO 14189\nTable 2\nPrescribed performance characteristics for methods of analysis for chemical and indicator parameters: trueness, precision and limit of detection (on or before 31 December 2019)\nParameter\nTrueness % of prescribed\nconcentration or value or specification\n(except for pH)\nPrecision % of prescribed\nconcentration or value or specification\n(except for pH)\nLimit of detection %\nof prescribed\nconcentration or\nvalue or specification\n(except for pH)\n(1)The method of analysis should determine total cyanide in all forms.\n(2)EN ISO 8476.\n(3)The performance characteristics apply to each individual pesticide and will depend on the pesticide concerned. Values for the uncertainty of measurement as low as 30% can be achieved for several pesticides, higher values up to 80% may be allowed for a number of pesticides.\n(4)The performance characteristics apply to the individual substances specified at 25% of the parametric value in Table B of Part 1 of Schedule 1.\n(5)The performance characteristics apply to the individual substances specified at 50% of the parametric value in Table B of Part 1of Schedule 1.\n(6)The performance characteristics apply to the prescribed value of 4 NTU.\n(7)The performance characteristics apply to the specification of 1 NTU for surface waters or ground waters influenced by surface water.\nAluminium\n10\n10\n10\nAmmonium\n10\n10\n10\nAntimony\n25\n25\n25\nArsenic\n10\n10\n10\nBenzene\n25\n25\n25\nBenzo(a)pyrene\n25\n25\n25\nBoron\n10\n10\n10\nBromate\n25\n25\n25\nCadmium\n10\n10\n10\nChloride\n10\n10\n10\nChromium\n10\n10\n10\nColour\n10\n10\n10\nConductivity\n10\n10\n10\nCopper\n10\n10\n10\nCyanide\n10\n10\n10\n1.2-dichloroethane\n25\n25\n10\nFluoride\n10\n10\n10\nHydrogen ion concentration pH (expressed in pH units)\n0.2\n0.2\nIron\n10\n10\n10\nLead\n10\n10\n10\nManganese\n10\n10\n10\nMercury\n20\n10\n20\nNickel\n10\n10\n10\nNitrate\n10\n10\n10\nNitrite\n10\n10\n10\nOxidisability\nPesticides and related products\n25\n25\n25\nPolycyclic aromatic hydrocarbons\n25\n25\n25\nSelenium\n10\n10\n10\nSodium\n10\n10\n10\nSulphate\n10\n10\n10\nTetrachloroethene\n25\n25\n10\nTetrachloromethane\n20\n20\n20\nTrichloroethene\n25\n25\n10\nTrihalomethanes:\nTotal\n25\n25\n10\nTurbidity\n10\n10\n10\nTurbidity\n25\n25\n25\nTable 3\nMethod of analysis for chemical and indicator parameters: uncertainty of measurement\nParameter\nUncertainty of measurement\n% of parametric value\n(except for pH)\n(1)The uncertainty of measurement must not be used as an additional tolerance to the parametric values set out in Schedule 1.\n(2)If the value of uncertainty of measurement cannot be met, the best available technique should be selected (up to 60%).\n(3)The method of analysis should determine total cyanide in all forms.\n(4)EN ISO 8476.\n(5)The performance characteristics apply to each individual pesticide and will depend on the pesticide concerned. Values for the uncertainty of measurement as low as 30% can be achieved for several pesticides, higher values up to 80% may be allowed for a number of pesticides.\n(6)The performance characteristics apply to the individual substances specified at 25% of the parametric value in Table B of Part 1 of Schedule 1.\n(7)The performance characteristics apply to the individual substances specified at 50% of the parametric value in Table B of Part 1 of Schedule 1.\n(8)The uncertainty of measurement must be estimated at the level of 3mg/l of TOC. CEN 1484 Guidelines for the determination of TOC and dissolved organic carbon must be used.\n(9)The uncertainty of measurement must be estimated at the level of 1,0 NTU in accordance with EN ISO 7027.\nAluminium\n25\nAmmonium\n40\nAntimony\n40\nArsenic\n30\nBenzene\n40\nBenzo(a)pyrene\n50\nBoron\n25\nBromate\n40\nCadmium\n25\nChloride\n15\nChromium\n30\nConductivity\n20\nCopper\n25\nCyanide\n30\n1,2-dichloroethane\n40\nFluoride\n20\nHydrogen ion concentration pH (expressed in pH units)\n0.2\nIron\n30\nLead\n25\nManganese\n30\nMercury\n30\nNickel\n25\nNitrate\n15\nNitrite\n20\nOxiedisability\n50\nPesticides\n30\nPolycyclic aromatic hydrocarbons\n50\nSelenium\n40\nSodium\n15\nSulphate\n15\nTetrachloroethene\n30\nTrichloroethene\n40\nTrihalomethanes: total\n40\nTotal organic carbon (TOC)\n30\nTurbidity\n30",
  "extent": "E+W",
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "I",
      "label": "I1",
      "text": "Sch. 4 Pt. 2 in force at 20.11.2017, see reg. 1"
    },
    {
      "type": "footnote",
      "label": "f1",
      "text": "(1)The method of analysis should determine total cyanide in all forms."
    },
    {
      "type": "footnote",
      "label": "f2",
      "text": "(2)EN ISO 8476."
    },
    {
      "type": "footnote",
      "label": "f3",
      "text": "(3)The performance characteristics apply to each individual pesticide and will depend on the pesticide concerned. Values for the uncertainty of measurement as low as 30% can be achieved for several pesticides, higher values up to 80% may be allowed for a number of pesticides."
    },
    {
      "type": "footnote",
      "label": "f4",
      "text": "(4)The performance characteristics apply to the individual substances specified at 25% of the parametric value in Table B of Part 1 of Schedule 1."
    },
    {
      "type": "footnote",
      "label": "f5",
      "text": "(5)The performance characteristics apply to the individual substances specified at 50% of the parametric value in Table B of Part 1of Schedule 1."
    },
    {
      "type": "footnote",
      "label": "f6",
      "text": "(6)The performance characteristics apply to the prescribed value of 4 NTU."
    },
    {
      "type": "footnote",
      "label": "f7",
      "text": "(7)The performance characteristics apply to the specification of 1 NTU for surface waters or ground waters influenced by surface water."
    },
    {
      "type": "footnote",
      "label": "f8",
      "text": "(1)The uncertainty of measurement must not be used as an additional tolerance to the parametric values set out in Schedule 1."
    },
    {
      "type": "footnote",
      "label": "f9",
      "text": "(2)If the value of uncertainty of measurement cannot be met, the best available technique should be selected (up to 60%)."
    },
    {
      "type": "footnote",
      "label": "f10",
      "text": "(3)The method of analysis should determine total cyanide in all forms."
    },
    {
      "type": "footnote",
      "label": "f11",
      "text": "(4)EN ISO 8476."
    },
    {
      "type": "footnote",
      "label": "f12",
      "text": "(5)The performance characteristics apply to each individual pesticide and will depend on the pesticide concerned. Values for the uncertainty of measurement as low as 30% can be achieved for several pesticides, higher values up to 80% may be allowed for a number of pesticides."
    },
    {
      "type": "footnote",
      "label": "f13",
      "text": "(6)The performance characteristics apply to the individual substances specified at 25% of the parametric value in Table B of Part 1 of Schedule 1."
    },
    {
      "type": "footnote",
      "label": "f14",
      "text": "(7)The performance characteristics apply to the individual substances specified at 50% of the parametric value in Table B of Part 1 of Schedule 1."
    },
    {
      "type": "footnote",
      "label": "f15",
      "text": "(8)The uncertainty of measurement must be estimated at the level of 3mg/l of TOC. CEN 1484 Guidelines for the determination of TOC and dissolved organic carbon must be used."
    },
    {
      "type": "footnote",
      "label": "f16",
      "text": "(9)The uncertainty of measurement must be estimated at the level of 1,0 NTU in accordance with EN ISO 7027."
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/wsi/2017/1041/schedule/4/part/2",
    "retrieved_at": "2026-10-28T23:24:57.489600+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."
}