Portsmouth Flood Risk
Portsmouth has a Low flood risk from rivers and the sea , with 2.9% of homes in a Medium or High band. The nearest gauge is 6.9 km away.
Portsmouth has 222,265 residents and 98,252 homes. Ranked 1114 of 7,114 in England for rivers and sea flood risk.
What Is The River Level Near Portsmouth Right Now?
The nearest gauge is Browndown, 6.9 km from the centre of Portsmouth, at Gosport. Its typical range is 0.13 m to 1.6 m, and the highest level on record is 1.72 m, reached on 24 December 2013.
No current reading has been published for this gauge.
When Has Portsmouth Flooded Before?
The Environment Agency holds 1 recorded flood outlines covering Portsmouth, the most recent dated 10 March 2008.
Absence of a record is not evidence that a place has never flooded — the Environment Agency states that a lack of coverage does not mean an area has never flooded.
What Does Portsmouth's Flood Risk Classification Mean?
8.8% of postcodes in Portsmouth sit in Flood Zone 3, the planning band for land with a 1% or greater annual chance of river flooding or 0.5% or greater of sea flooding — and the map that draws it deliberately ignores flood defences.
The flood risk band for rivers and the sea is Low , with 2.9% of homes in a Medium or High band. Unlike the Flood Zone, the band counts the defences that are actually in place, which is why the two can describe the same street differently and both be right.
Which Postcode Districts Cover Portsmouth?
Each district below is one postcode district that falls inside Portsmouth. The band is the one shared by most of that district's postcodes, so it describes the district rather than a single street — enter a full postcode in the checker for one address. A district can cover more than one town, and the district pages linked from the checker are keyed to the town that holds most of its postcodes.
| Postcode district | Postcodes here | Rivers and sea band | Surface water addresses |
|---|---|---|---|
| PO6 | 866 | Low | 1,363 |
| PO1 | 793 | Low | 3,255 |
| PO2 | 731 | Low | 1,571 |
| PO4 | 727 | Low | 2,388 |
| PO5 | 640 | Low | 1,289 |
| PO3 | 406 | Low | 650 |
| PO16 | 378 | Low | 289 |
| PO9 | 18 | Medium | 11 |
| PO17 | 2 | Not mapped — no rivers-and-sea band covers this district | not published for this district |
"Not mapped" is not "no risk". It means no rivers-and-sea band covers that district in the source — surface water can still flood it, and both Camden and Islington flooded from surface water in July 2021 while carrying no mapped rivers-and-sea band.
What Else Is Near Portsmouth?
Other places on the River Alver, nearest to Portsmouth first.