Does CM4 flood?

Yes — parts of the CM4 district carry real flood risk: 12 of its 24 at-risk postcodes reach the Environment Agency's High likelihood band. The CM4 postcode district covers Ingatestone, Fryerning & Mountnessing, South Hanningfield, Stock and Margaretting, Blackmore & Doddinghurst, Chelmsford Rural West, close to Mountnessing, Billericay, Widford, and surrounding villages in parts of Essex and England.

24 postcodes in the CM4 district appear in the Environment Agency's rivers-and-sea flood-risk dataset — worst bands: 12 high, 3 medium, 9 low. A postcode not listed here has no properties in any recorded risk band (which is good news, but never proof it cannot flood).

Free preview first · full report £19

Which CM4 postcodes are at risk?

CM4 0BA up to High CM4 0BU up to High CM4 0DD up to High CM4 0EG up to High CM4 0EQ up to High CM4 0EW up to High CM4 0FG up to High CM4 0PU up to High CM4 9AE up to High CM4 9AR up to High CM4 9PD up to High CM4 9QN up to High CM4 0QE up to Medium CM4 9AD up to Medium CM4 9AH up to Medium CM4 0BY up to Low CM4 0LU up to Low CM4 0NZ up to Low CM4 0RR up to Low CM4 9AJ up to Low CM4 9AW up to Low CM4 9DR up to Low CM4 9NN up to Low CM4 9NS up to Low

Rivers and flooding history near CM4

The rivers that matter here, each monitored live on FloodRadar:

Mountnessing on the River Wid — 3.5 km away, highest on record 2.75m
Wardropers on the River Wid — 3.6 km away, highest on record 2.34m
WRITTLE GS GSM — 7.4 km away
Writtle on the River Wid — 7.5 km away, highest on record 1.30m

219 official flood warnings and alerts have been raised within ~10 km of the district's centre since 2006 (49 at warning level or above), most recently 19 February 2026. Warnings cover flood areas, not individual addresses.

Recorded flood extents near the district (Environment Agency record):

1968 September Flood Outline (1968) — about 50.1 km from the centre
1958 Flood Outline (1958) — about 12.9 km from the centre
1953 Coast Flood Outline Essex (1953) — about 32.3 km from the centre
1947 Flood Outline (1947) — about 22.9 km from the centre

Records, not floods: no outline on the record is not evidence a place has not flooded.

🏠 Buying or renting in CM4? The full property flood-risk report covers any postcode here — the official likelihood band, every recorded flood nearby with distances, warning history year by year, how the local rivers behave, and an insurance outlook, print-ready for £19. See what's in the report →

Flood risk in nearby postcode districts

CM3 CM5 CM2 CM6 CM1 CM7 CM0 CM8

Band = the worst likelihood band of any property in that postcode (EA Risk of Flooding from Rivers & Sea, defence-adjusted, area-level). Check any postcode in detail — or get the full £19 property report — at the property flood-risk report. © Environment Agency copyright and/or database right 2025. All rights reserved. Some features of this map are based on digital spatial data from the Centre for Ecology & Hydrology, © NERC (CEH). © Crown Copyright and Database Rights 2025 OS AC0000807064. This product is produced in part from PAF® and Multiple Residence Data, the copyright in which is owned by Royal Mail Group Limited and/or Royal Mail Group plc. All rights reserved. Licence number AC0000807064.