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Avon Water

A stream near Sway, Hampshire. No gauge of its own: what the river map and the banked data say about it.

Avon Water is a stream on Ordnance Survey’s river map near Sway, Hampshire, with about 17 km of mapped channel. On the map it flows into Keyhaven Lake and out to the sea.

Next gauge downstream

None before the water reaches tidal water, about 10 m downstream. Below that, gauges read the tide.

Storm overflows on Avon Water

1 storm overflow is placed on this stream on the river map. Each status is the water company’s own monitor.

Flexford Lane Sway WwTW Not discharging bathing water
Southern Water · into Avon Water · 2025: 43 spills, 508 h

A status says whether an overflow is discharging now, never how much or why. A monitor that is offline or has not reported is not “not discharging”. Sewage in Britain’s rivers →

Live status: © Southern Water storm overflow activity data, licensed under CC BY 4.0. Annual spill figures: Environment Agency Event Duration Monitoring return, © Environment Agency copyright and/or database right, Open Government Licence (OGL) v3.0.

Water-sampling points on Avon Water

5 Environment Agency sampling points are placed on this stream. These are dated samples taken by hand, not live readings, and FloodRadar does not grade them.

Arnewood Manor
Last sampled 14 Sep 2026 · 17 days ago · 6 samples banked
Avon Water Efford Mill
Last sampled 14 Sep 2026 · 17 days ago · 27 samples banked
Downstream Holmsley A35, Avon Water
Last sampled 10 Sep 2026 · 21 days ago · 4 samples banked
Upstream of Wootton Road Bridge, Avon Water
Last sampled 6 Mar 2026 · 7 months ago · 24 samples banked
Avon Water Gordleton (closed)
No sample published 1 Oct 2023 – 30 Sep 2026

A sample is taken on a date; it says nothing about the water today. A sample below an overflow does not by itself show where anything in it came from.

Water samples: Environment Agency Water Quality Archive, © Environment Agency and/or database right 2026, Open Government Licence v3.0.

Places along it

From its source towards its mouth, the settlements within a kilometre of it on the map: Sway, Upper Pennington, Lower Pennington, Lymore, Keyhaven.

On the map

The map needs JavaScript. Everything it shows is listed on this page.

The blue line is Avon Water; grey lines are other mapped watercourses. Lines from OS Open Rivers (edition 2026-04).

SO41 0TR, a postcode page near where it ends on the map (about 140 m away) →All rivers with gauges →

What this page can and cannot tell you

Its line, its name and where it flows come from Ordnance Survey’s river map (OS Open Rivers, edition 2026-04), which leaves out many small streams, ditches and culverts. “Flows into” is the map’s word: a channel that is not on the map is not shown here, which does not mean it is not there.
No gauge measures Avon Water itself, so its own level is not known here.
Storm overflows are listed only where the river map places them on this stream; an overflow it could not place is not counted.
Water samples are England’s only (the Environment Agency’s archive), placed where the map can place their sampling point.
Nothing on this page says whether any place floods. For an address, see its postcode page.