{
  "url": "https://openlegislation.uk/water-supply-water-quality-regulations-northern-ireland-2002/schedule-3/part-IV",
  "json_url": "https://openlegislation.uk/water-supply-water-quality-regulations-northern-ireland-2002/schedule-3/part-IV.json",
  "legislation": "nisr/2002/331",
  "legislation_title": "The Water Supply (Water Quality) Regulations (Northern Ireland) 2002",
  "legislation_url": "https://openlegislation.uk/water-supply-water-quality-regulations-northern-ireland-2002",
  "path": "schedule/3/part/IV",
  "kind": "part",
  "number": "IV",
  "heading": "MONITORING",
  "text": "TABLE 1.\nPARAMETERS AND CIRCUMSTANCES FOR CHECK MONITORING\n(1)\n(2)\n(3)\nItem\nParameter\nCircumstances\n1.\nAluminium\nWhen used as flocculant or where the water originates from, or is influenced by, surface waters\n2.\nAmmonium\n3.\nClostridium perfringens (including spores)\nWhere the water originates from, or is influenced by, surface waters\n4.\nColiform bacteria\n5\nColony Counts\n6.\nColour\n7.\nConductivity\n8.\nEscherichia coli (E. coli)\n9.\nHydrogen ion\n10.\nIron\nWhen used as flocculant or where the water originates from, or is influenced by, surface waters\n11.\nManganese\nWhere the water originates from, or is influenced by, surface waters\n12.\nNitrate\nWhen chloramination is practised\n13.\nNitrite\nWhen chloramination is practised\n14.\nOdour\n15.\nTaste\n16.\nTurbidity\nTABLE 2.\nANNUAL SAMPLING FREQUENCIES: WATER SUPPLY ZONES\n(1)\n(2)\n(3)\n(4)\nSubstances and parameters subject to check monitoring\nEstimated population of water supply zone\nReduced\nStandard\nNotes:\n*Sampling for these parameters may be within water supply zones or at supply points as specified in Table 3, subject to notes (ii) and ((iii)) below.\n(i)Where the population is not an exact multiple of 5,000, the population figure should be rounded up to the nearest multiple of 5,000.\n(ii)Check monitoring in water supply zones is required only where chloramination is practised. In other circumstances audit monitoring is required.\n(iii)Audit monitoring in water supply zones is required only where sodium hypochlorite is added after water has left the treatment works. In other circumstances, audit monitoring is required at supply points.\n(iv)To monitor for total indicative dose (for radioactivity).\nE. coli }\n<100\n4\nColiform bacteria }\nResidual disinfectant }\n≥100\n12 per 5,000 population\nAluminium }\nAmmonium }\nClostridium perfringens }\n(including spores) }\nColony counts }\nColour }\n<100\n1\n2\nConductivity }\n100–4,999\n2\n4\nHydrogen ion }\n5,000–9,999\n6\n12\nIron }\n10,000–29,999\n12\n24\nManganese }\n30,000–49,999\n18\n36\nNitrate }\n50,000–79,999\n26\n52\nNitrite }\n80,000–100,000\n38\n76\nOdour }\nTaste }\nTurbidity }\nParameters subject to audit monitoring\nAluminium }\nAntimony }\nArsenic }\nBenzene }\nBenzo(a)pyrene }\nBoron }\nBromate }\nCadmium }\nChromium }\nCopper }\nCyanide }\n1,2 dichloroethane }\n<100\n1\nEnterococci }\n100–4,999\n4\nFluoride }\n5,000–100,000\n8\nIron }\nLead }\nManganese }\nMercury }\nNickel }\nNitrate }\nNitrite }\nPesticides and related products }\nPolycyclic aromatic hydrocarbons }\nSelenium }\nSodium }\nTrichloroethene/Tetrachloroethene }\nTetrachloromethane }\nTrihalomethanes }\n<100\n1\nChloride }\n100–4,999\n4\nSulphate }\n5,000–100,000\n8\nTotal organic carbon }\nTritium }\nGross alpha }\nGross beta }\nTABLE 3.\nANNUAL SAMPLING FREQUENCIES: TREATMENT WORKS OR SUPPLY POINTS\n(1)\n(2)\n(3)\n(4)\n(5)\nItem\nSubstances and parameters\nVolume of water supplied m3/d\nReduced\nStandard\nNotes:\n*Sampling is at treatment works for the substances and parameters shown in column (1) of the Table as items 1 to 6 and at supply points for the other substances and parameters, except nitrite, subject to notes (ii) and (iii);\n(i)Check monitoring is required only in respect of surface waters (see regulation 6(2) and Table 1 in Schedule 3).\n(ii)Sampling at treatment works when chloramination is practised.\n(iii)Sampling at treatment works when chloromination is not practised.\n(iv)Audit monitoring at supply points is required only where sodium hypochlorite is not added after water has left the treatment works. In other circumstances, audit monitoring is required in water supply zones.\n(v)To monitor for total indicative dose (for radioactivity).\n1.\nE. coli }\n<20\n4\n2.\nColiform bacteria }\n20–1,999\n12\n52\n3.\nColony counts }\n2,000–5,999\n52\n104\n4.\nNitrite }\n6,000–11,999\n104\n208\n5.\nResidual disinfectant }\n≥12,000\n104\n365\n6.\nTurbidity }\nSubject to check monitoring\n7.\nClostridium perfringens }\n<20\n2\n}\n20–999\n2\n4\n8.\nConductivity }\n1,000–1,999\n6\n12\n}\n2,000–5,999\n12\n24\n}\n6,000–9,999\n18\n36\n}\n10,000–15,999\n26\n52\n}\n16,000–32,999\n52\n104\n}\n33,000–49,999\n78\n156\n}\n50,000–67,999\n104\n208\n}\n68,000–84,999\n130\n260\n}\n85,000–101,999\n156\n312\n}\n102,000–119,999\n183\n365\n}\n120,000–241,999\n365\n730\n}\n242,000–484,999\n730\n1,460\n}\n485,000–728,999\n1,095\n2,190\nSubject to audit monitoring\n9.\nBenzene }\n10.\nBoron }\n11.\nBromate }\n12.\nCyanide }\n13.\n1,2 dichloroethane }\n<20\n1\n14.\nFluoride }\n20–999\n4\n15.\nMercury }\n1,000–49,999\n8\n16.\nNitrite }\n50,000–89,999\n12\n17.\nPesticides and }\n90,000–299,999\n24\nrelated products }\n300,000–649,999\n36\n18.\nTrichloroethene }\n≥650,000\n48\nTetrachloroethene }\n19.\nTetrachloromethane }\n20.\nChloride }\n21.\nSulphate }\n22.\nTotal organic carbon }\n23.\nTritium }\n24.\nGross alpha }\n25.\nGross beta }",
  "extent": "N.I.",
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "footnote",
      "label": "f1",
      "text": "(i)Where the population is not an exact multiple of 5,000, the population figure should be rounded up to the nearest multiple of 5,000."
    },
    {
      "type": "footnote",
      "label": "f2",
      "text": "*Sampling for these parameters may be within water supply zones or at supply points as specified in Table 3, subject to notes (ii) and ((iii)) below."
    },
    {
      "type": "footnote",
      "label": "f3",
      "text": "(ii)Check monitoring in water supply zones is required only where chloramination is practised. In other circumstances audit monitoring is required."
    },
    {
      "type": "footnote",
      "label": "f4",
      "text": "(iii)Audit monitoring in water supply zones is required only where sodium hypochlorite is added after water has left the treatment works. In other circumstances, audit monitoring is required at supply points."
    },
    {
      "type": "footnote",
      "label": "f5",
      "text": "(iv)To monitor for total indicative dose (for radioactivity)."
    },
    {
      "type": "footnote",
      "label": "f6",
      "text": "(ii)Sampling at treatment works when chloramination is practised."
    },
    {
      "type": "footnote",
      "label": "f7",
      "text": "(i)Check monitoring is required only in respect of surface waters (see regulation 6(2) and Table 1 in Schedule 3)."
    },
    {
      "type": "footnote",
      "label": "f8",
      "text": "(iv)Audit monitoring at supply points is required only where sodium hypochlorite is not added after water has left the treatment works. In other circumstances, audit monitoring is required in water supply zones."
    },
    {
      "type": "footnote",
      "label": "f9",
      "text": "(iii)Sampling at treatment works when chloromination is not practised."
    },
    {
      "type": "footnote",
      "label": "f10",
      "text": "(v)To monitor for total indicative dose (for radioactivity)."
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/nisr/2002/331/schedule/3/part/IV",
    "retrieved_at": "2026-10-29T02:06:16.045012+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."
}