Witney has some flood risk, concentrated in a minority of streets. Most postcodes are clear of the river zones. About one in nine is high risk on at least one measure. The last recorded flood came from overflowing drains, and the Windrush overflowing did not cause it. The town's name comes from the Old English for "Witta's island", which tells you its founders knew where the water went.
In the Environment Agency's river-and-sea flood zones, about 2% of the area's postcodes are in Flood Zone 3, the highest-probability band, and about 8% more are in Flood Zone 2, the medium-probability band. The two bands do not overlap, so Zone 2 is the extra fringe of risk beyond Zone 3. Witney grew up as a crossing over the River Windrush, and the river sets the boundaries of both zones.
The town's flood record shows surface water is the main problem. The Environment Agency holds 35 recorded flood events for the area. The latest was in July 2007, and the record files the cause under local drainage and surface water, with the main river as the source. About 3% of the area falls inside the outline of a past recorded flood. On wet nights, a blocked drain can flood a street that river maps would never show.
The Environment Agency's climate-adjusted mapping puts about 16% of postcodes inside the flood zones once future rainfall and river flows are allowed for, roughly double the area in today's zones. Those are modelled outlines, and they show where the risk would spread if the climate assumptions hold.
Homes in Zone 3 or near the river can expect insurers to ask more questions and quote higher premiums, and a past claim on a property usually makes both worse. Most of Witney's estates fall outside the river zones and should be insured as ordinary homes. Get the Environment Agency's long-term flood risk result for the exact address, then an insurance quote, early on for any house near the Windrush; two streets apart can mean two different premiums.
Counting every postcode against several measures at once, surface water included, about 11% of Witney's postcodes are high risk on at least one of them, about 13% medium and about 33% low. A postcode only needs one measure to count, so these shares are wider than the river zones above.
The Environment Agency's rivers-and-sea mapping lists 112 postcodes in Witney with some risk, covering 2,308 properties. Of those, 225 properties are at high risk, 179 of them homes, with 79 more at medium risk and 1,146 at low risk. Postcodes with no river or sea risk do not appear in that count at all. Two hundred and twenty-five sounds small next to a town this size, unless one of them is the house you are buying.
The high-risk flood extent covers about 2% of postcodes whether or not the Environment Agency's model includes flood defences. "Defended" only means the model includes a defence nearby, and here including it makes no difference to how many postcodes fall in the high-risk area. Nobody should read the word as reassurance.
The nearest tide gauge to Witney is at Portsmouth. It recorded sea level rising about 2 millimetres a year between 1962 and 2023. For a town on the Windrush deep in Oxfordshire, that tells you how little the sea matters here.
Witney's flood risk is middling. It is serious along the river and in the surface-water hotspots, and most of the town is unaffected.