{ "name": "floodriskassessmentcost.co.uk Flood Risk Planning Rules", "title": "Flood Risk Planning Rules", "url": "https://floodriskassessmentcost.co.uk/datasets/flood-risk-planning-rules/", "csv": "https://floodriskassessmentcost.co.uk/datasets/flood-risk-planning-rules.csv", "markdown": "https://floodriskassessmentcost.co.uk/datasets/flood-risk-planning-rules/index.md", "computed_at": "2026-10-28", "license": "https://floodriskassessmentcost.co.uk/terms", "headline": "The Flood Risk Planning Rules carries 9 published figures read from 3 sources' own pages, from 0.10 to 3.30 percent, read 27 October 2026.", "quotes": [ "The Flood Risk Planning Rules carries 9 published figures read from 3 sources' own pages, from 0.10 to 3.30 percent, read 27 October 2026.", "3 of the 9 named sources read in full publish a figure; 6 publish none, read 27 October 2026.", "Flood Risk Planning Rules, rule design-flood-river: median 1 percent across 1 source, read 27 October 2026.", "Flood Risk Planning Rules, rule design-flood-tidal: median 0.50 percent across 1 source, read 27 October 2026.", "Flood Risk Planning Rules, rule design-flood-surface-water: median 1 percent across 1 source, read 27 October 2026.", "Flood Risk Planning Rules, rule flood-zone-1: median 0.10 percent across 1 source, read 27 October 2026.", "Flood Risk Planning Rules, rule flood-zone-2: median 1 percent across 1 source, read 27 October 2026.", "Flood Risk Planning Rules, rule flood-zone-3a: median 1 percent across 1 source, read 27 October 2026.", "Flood Risk Planning Rules, rule flood-zone-3b: median 3.30 percent across 1 source, read 27 October 2026.", "Flood Risk Planning Rules, rule minor-extension: median 3.30 percent across 1 source, read 27 October 2026.", "Flood Risk Planning Rules, rule access-and-escape: median 0.10 percent across 1 source, read 27 October 2026." ], "citation": "\"floodriskassessmentcost.co.uk Flood Risk Planning Rules\", updated 2026-10-28, https://floodriskassessmentcost.co.uk/datasets/flood-risk-planning-rules/.", "changed_since": null, "national": { "unit": "%", "n": 9, "median": 1, "min": 0.1, "max": 3.3, "p25": 0.3, "p75": 2.15, "mean": 1.2556, "units": { "%": 9 }, "published_sources": 3, "named_sources": 12, "read_sources": 9, "not_published": 6, "published_share": 0.333 }, "by_axis": { "rule": { "design-flood-river": { "%": { "n": 1, "median": 1, "min": 1, "max": 1, "p25": 1, "p75": 1, "mean": 1 } }, "design-flood-tidal": { "%": { "n": 1, "median": 0.5, "min": 0.5, "max": 0.5, "p25": 0.5, "p75": 0.5, "mean": 0.5 } }, "design-flood-surface-water": { "%": { "n": 1, "median": 1, "min": 1, "max": 1, "p25": 1, "p75": 1, "mean": 1 } }, "flood-zone-1": { "%": { "n": 1, "median": 0.1, "min": 0.1, "max": 0.1, "p25": 0.1, "p75": 0.1, "mean": 0.1 } }, "flood-zone-2": { "%": { "n": 1, "median": 1, "min": 1, "max": 1, "p25": 1, "p75": 1, "mean": 1 } }, "flood-zone-3a": { "%": { "n": 1, "median": 1, "min": 1, "max": 1, "p25": 1, "p75": 1, "mean": 1 } }, "flood-zone-3b": { "%": { "n": 1, "median": 3.3, "min": 3.3, "max": 3.3, "p25": 3.3, "p75": 3.3, "mean": 3.3 } }, "minor-extension": { "%": { "n": 1, "median": 3.3, "min": 3.3, "max": 3.3, "p25": 3.3, "p75": 3.3, "mean": 3.3 } }, "access-and-escape": { "%": { "n": 1, "median": 0.1, "min": 0.1, "max": 0.1, "p25": 0.1, "p75": 0.1, "mean": 0.1 } } } }, "rows": [ { "source": "Planning Practice Guidance - flood risk and coastal change", "url": "https://www.gov.uk/guidance/flood-risk-and-coastal-change", "figure": "1%", "value": 1, "unit": "%", "vat": null, "axis": { "rule": "design-flood-river" }, "retrieved_at": "2026-10-27", "quote": "river flooding likely to occur with a 1% annual probability (a 1 in 100 chance each year); or", "source_class": "primary-government", "text_sha256": "fd9e16b777478312545ed94c21a457f0109e6968a245c158af4a932ab89899dd" }, { "source": "Planning Practice Guidance - flood risk and coastal change", "url": "https://www.gov.uk/guidance/flood-risk-and-coastal-change", "figure": "0.5%", "value": 0.5, "unit": "%", "vat": null, "axis": { "rule": "design-flood-tidal" }, "retrieved_at": "2026-10-27", "quote": "tidal flooding with a 0.5% annual probability (1 in 200 chance each year); or", "source_class": "primary-government", "text_sha256": "fd9e16b777478312545ed94c21a457f0109e6968a245c158af4a932ab89899dd" }, { "source": "Planning Practice Guidance - flood risk and coastal change", "url": "https://www.gov.uk/guidance/flood-risk-and-coastal-change", "figure": "1%", "value": 1, "unit": "%", "vat": null, "axis": { "rule": "design-flood-surface-water" }, "retrieved_at": "2026-10-27", "quote": "surface water flooding likely to occur with a 1% annual probability (a 1 in 100 chance each year),", "source_class": "primary-government", "text_sha256": "fd9e16b777478312545ed94c21a457f0109e6968a245c158af4a932ab89899dd" }, { "source": "Planning Practice Guidance - flood risk and coastal change", "url": "https://www.gov.uk/guidance/flood-risk-and-coastal-change", "figure": "0.1%", "value": 0.1, "unit": "%", "vat": null, "axis": { "rule": "flood-zone-1" }, "retrieved_at": "2026-10-27", "quote": "Zone 1 Low Probability Land having a less than 0.1% annual probability of river or sea flooding.", "source_class": "primary-government", "text_sha256": "fd9e16b777478312545ed94c21a457f0109e6968a245c158af4a932ab89899dd" }, { "source": "Planning Practice Guidance - flood risk and coastal change", "url": "https://www.gov.uk/guidance/flood-risk-and-coastal-change", "figure": "1%", "value": 1, "unit": "%", "vat": null, "axis": { "rule": "flood-zone-2" }, "retrieved_at": "2026-10-27", "quote": "Zone 2 Medium Probability Land having between a 1% and 0.1% annual probability of river flooding; or land having between a 0.5% and 0.1% annual probability of sea flooding.", "source_class": "primary-government", "text_sha256": "fd9e16b777478312545ed94c21a457f0109e6968a245c158af4a932ab89899dd" }, { "source": "Planning Practice Guidance - flood risk and coastal change", "url": "https://www.gov.uk/guidance/flood-risk-and-coastal-change", "figure": "1%", "value": 1, "unit": "%", "vat": null, "axis": { "rule": "flood-zone-3a" }, "retrieved_at": "2026-10-27", "quote": "Zone 3a High Probability Land having a 1% or greater annual probability of river flooding; or Land having a 0.5% or greater annual probability of sea.", "source_class": "primary-government", "text_sha256": "fd9e16b777478312545ed94c21a457f0109e6968a245c158af4a932ab89899dd" }, { "source": "Planning Practice Guidance - flood risk and coastal change", "url": "https://www.gov.uk/guidance/flood-risk-and-coastal-change", "figure": "3.3%", "value": 3.3, "unit": "%", "vat": null, "axis": { "rule": "flood-zone-3b" }, "retrieved_at": "2026-10-27", "quote": "• land having a 3.3% or greater annual probability of flooding, with any existing flood risk management infrastructure operating effectively; or", "source_class": "primary-government", "text_sha256": "fd9e16b777478312545ed94c21a457f0109e6968a245c158af4a932ab89899dd" }, { "source": "Flood risk assessments: applying for planning permission", "url": "https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications", "figure": "3.3%", "value": 3.3, "unit": "%", "vat": null, "axis": { "rule": "minor-extension" }, "retrieved_at": "2026-10-27", "quote": "present day 3.3% annual probability extent of river and sea flooding with defences", "source_class": "primary-government", "text_sha256": "3f0bd895d18d43f8cbc8a50fa4fefc469f395c938b71be74bbf443876591c4a7" }, { "source": "Preparing a flood risk assessment: standing advice", "url": "https://www.gov.uk/guidance/flood-risk-assessment-standing-advice", "figure": "0.1%", "value": 0.1, "unit": "%", "vat": null, "axis": { "rule": "access-and-escape" }, "retrieved_at": "2026-10-27", "quote": "how the development could be evacuated before an extreme flood – this is an event with a 0.1% annual probability of flooding plus an allowance for climate change", "source_class": "primary-government", "text_sha256": "bf3353532af0a70f5ebf6d7456dd31434ca6a12a412a24f12e0bd3c3233ed30c" } ], "not_published": [ { "source": "Flood risk assessments: the sequential test for applicants", "url": "https://www.gov.uk/guidance/flood-risk-assessment-the-sequential-test-for-applicants", "retrieved_at": "2026-10-27", "reason": "every candidate on the page was refused" }, { "source": "National flood risk standing advice for local planning authorities", "url": "https://www.gov.uk/guidance/flood-risk-assessment-local-planning-authorities", "retrieved_at": "2026-10-27", "reason": "read in full and no accepted figure on the page" }, { "source": "Check the long term flood risk for an area", "url": "https://www.gov.uk/check-long-term-flood-risk", "retrieved_at": "2026-10-27", "reason": "read in full and no accepted figure on the page" }, { "source": "NPPF chapter 14 - flooding and coastal change", "url": "https://www.gov.uk/guidance/national-planning-policy-framework/14-meeting-the-challenge-of-climate-change-flooding-and-coastal-change", "retrieved_at": "2026-10-27", "reason": "read in full and no accepted figure on the page" }, { "source": "Welsh Government - TAN 15 development, flooding and coastal erosion", "url": "https://www.gov.wales/technical-advice-note-tan-15-development-flooding-and-coastal-erosion", "retrieved_at": "2026-10-27", "reason": "read in full and no accepted figure on the page" }, { "source": "SEPA - planning guidance and advice notes", "url": "https://www.sepa.org.uk/environment/land/planning/guidance-and-advice-notes/", "retrieved_at": "2026-10-27", "reason": "read in full and no accepted figure on the page" } ], "sources": [ { "url": "https://www.gov.uk/guidance/flood-risk-and-coastal-change", "label": "Planning Practice Guidance - flood risk and coastal change", "license": "the publisher's own terms; quoted for reporting and comment" }, { "url": "https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications", "label": "Flood risk assessments: applying for planning permission", "license": "the publisher's own terms; quoted for reporting and comment" }, { "url": "https://www.gov.uk/guidance/flood-risk-assessment-standing-advice", "label": "Preparing a flood risk assessment: standing advice", "license": "the publisher's own terms; quoted for reporting and comment" }, { "url": "https://www.gov.uk/guidance/flood-risk-assessment-the-sequential-test-for-applicants", "label": "Flood risk assessments: the sequential test for applicants", "license": "the publisher's own terms; quoted for reporting and comment" }, { "url": "https://www.gov.uk/guidance/flood-risk-assessment-local-planning-authorities", "label": "National flood risk standing advice for local planning authorities", "license": "the publisher's own terms; quoted for reporting and comment" }, { "url": "https://flood-map-for-planning.service.gov.uk/", "label": "Flood map for planning", "license": "the publisher's own terms; quoted for reporting and comment" }, { "url": "https://www.gov.uk/check-long-term-flood-risk", "label": "Check the long term flood risk for an area", "license": "the publisher's own terms; quoted for reporting and comment" }, { "url": "https://www.gov.uk/government/publications/national-planning-policy-framework--2", "label": "National Planning Policy Framework", "license": "the publisher's own terms; quoted for reporting and comment" }, { "url": "https://www.gov.uk/guidance/national-planning-policy-framework/14-meeting-the-challenge-of-climate-change-flooding-and-coastal-change", "label": "NPPF chapter 14 - flooding and coastal change", "license": "the publisher's own terms; quoted for reporting and comment" }, { "url": "https://www.legislation.gov.uk/ukpga/2010/29/contents", "label": "Flood and Water Management Act 2010", "license": "the publisher's own terms; quoted for reporting and comment" }, { "url": "https://www.gov.wales/technical-advice-note-tan-15-development-flooding-and-coastal-erosion", "label": "Welsh Government - TAN 15 development, flooding and coastal erosion", "license": "the publisher's own terms; quoted for reporting and comment" }, { "url": "https://www.sepa.org.uk/environment/land/planning/guidance-and-advice-notes/", "label": "SEPA - planning guidance and advice notes", "license": "the publisher's own terms; quoted for reporting and comment" } ], "methodology": "Every row is a verbatim sentence read from the named source's own page through our fetch service on the date shown, hash-pinned to the stored read (the sha of the page's visible text; the raw page is mirrored to R2). 3 of the 9 named sources that could be read published a usable figure; 6 published none and are recorded as not published, never filled in; 3 could not be read (blocked, dead or unreachable) and count nowhere. The headline figures (median, minimum, maximum, quartiles) are over ONE figure per source for each breakdown it prices, in % (a source's median where its page yielded several accepted sentences for one breakdown), so a page that gives figures for several breakdowns gives one for each and N counts 9 figures, never sentences; 10 candidate sentence(s) were refused by a reviewer with the reason recorded. The fuller derivation this dataset is chartered to grow into (not yet what the figures above are; they are each source's own published figure as read): one row per rule: the trigger (flood zone, site area, development vulnerability, critical drainage area), the test it requires and the authority that applies it, per nation", "embed": "

0.10 to 3.30 percent

9 published figures, Flood Risk Planning Rules, across 3 sources, read 27 October 2026

Source: floodriskassessmentcost.co.uk Flood Risk Planning Rules
" }