FloodRadar
Log inCreate free account
Live levels from 9 monitoring stations across Essex, Hampshire, Surrey, Wokingham, updated every 15 minutes.
| Station | Level now | Status | ||
|---|---|---|---|---|
| Tongham | 0.73 mASD 1h ago | Normal | ||
| 8.0 km by river | ||||
| Farnborough | 0.78 mASD 1h ago | Normal | ||
| 5.1 km by river | ||||
| Blackwater Bridge | 1.38 mASD 1h ago | Normal | ||
| 10.6 km by river | ||||
| Eversley | 0.61 mASD 1h ago | Normal | ||
| 6.1 km by river | ||||
| Swallowfield | 0.25 mASD 1h ago | Normal | ||
| downstream, distance by river not measured | ||||
| Swallowfield Side Channelstructure | 0.25 mASD 1h ago | Normal | ||
| Station | Level now | Status | ||
|---|---|---|---|---|
| Stisted | 0.35 mASD 1h ago | Normal | ||
| 19.1 km by river | ||||
| Appleford Bridge | 0.35 mASD 1h ago | Normal | ||
| Station | Level now | Status |
|---|---|---|
| Owerplace estimated | 0.07 mASD 1h ago | Normal |
Stations are listed from source to mouth as the water flows, traced on the river map (OS Open Rivers) and the Environment Agency’s own links between its gauges. A distance “by river” is along the river, and is shown only where the map traces the path.
Contains OS data © Crown copyright and database rights 2026.
Streams and rivers with a gauge whose water joins the Blackwater above one of its gauges, from the source down. Named streams without a gauge that have a page here are listed at the end.
Joins the Blackwater between Farnborough and Blackwater Bridge, no more than 3.4 km by river above Blackwater Bridge.
| Cove Hazel Avenue | 0.87 mASD 3h ago | Normal |
| 2.1 km by river | ||
| Mayfield Roadstructure | 1.14 mASD 1h ago | Normal |
Its water passes Blackwater Bridge and every gauge below it on the Blackwater. It does not pass Farnborough or the gauges above it.
Joins the Blackwater between Eversley and Swallowfield, no more than 8.1 km by river above Swallowfield.
| Crondall Pondtidal | 0.40 mASD 2h ago | Normal |
| downstream, distance by river not measured | ||
| Crondall Bridge | 0.09 mASD 1h ago | Normal |
| 3.3 km by river | ||
| Crookham Village | 0.44 mASD 1h ago | Normal |
| 11.8 km by river | ||
| Bramshillstructure | 0.28 mASD 1h ago | Normal |
Its water passes Swallowfield and every gauge below it on the Blackwater. It does not pass Eversley or the gauges above it.
Joins the Blackwater between Eversley and Swallowfield, no more than 6.3 km by river above Swallowfield.
| Lodge Farmstructure | 0.11 mASD 1h ago | Normal |
| 11.3 km by river | ||
| River Whitewater at Holdshot Farm | 0.20 m3/s 1h ago | — |
Its water passes Swallowfield and every gauge below it on the Blackwater. It does not pass Eversley or the gauges above it.
Below Swallowfield Side Channel, its water next reaches Arborfield Bridge, a gauge on River Loddon, 4.3 km by river downstream.
Joins the Blackwater above Stisted, its highest gauge, no more than 22.1 km by river above Stisted.
| COPFORD HALL FGS DUAL COMMSplace estimated | 0.51 m3/s 1h ago | — |
| Copford Hallplace estimated | 0.26 mASD 1h ago | Normal |
Its water passes every gauge on the Blackwater, from Stisted down.
No gauge below Appleford Bridge is known on the river map.
No gauged tributary joins the Blackwater above Ower on the river map. Streams without a gauge are not counted here.
No gauge below Ower is known on the river map.
Tributaries and where they join are traced on the river map (OS Open Rivers, edition 2026-04) and the Environment Agency’s links between its gauges. The map holds distances between gauges, not the junctions themselves, so a junction is placed between two gauges, and no further up than the tributary’s own lowest gauge. Contains OS data © Crown copyright and database rights 2026.
12 storm overflows are traced upstream of Swallowfield Side Channel, the Blackwater’s lowest gauge on the river map: on the Blackwater itself, on its gauged tributaries, and on smaller streams that join above there.
Official figures for 2025, for the overflows traced upstream of Swallowfield Side Channel: 197 spills over 2,393 hours in total, across all 12.
Each overflow is listed in the stretch above the first gauge its water reaches, from the source down, as on the Gauges tab. A stretch of the Blackwater includes the smaller streams that join it there.
Within 3 km of one of the Blackwater’s gauges in a straight line, but the river map cannot say whether their water reaches it.
12 storm overflows are traced upstream of Appleford Bridge, the Blackwater’s lowest gauge on the river map: on the Blackwater itself, on its gauged tributaries, and on smaller streams that join above there.
Official figures for 2025, for the overflows traced upstream of Appleford Bridge: 40 spills over 229 hours in total, across all 12.
Each overflow is listed in the stretch above the first gauge its water reaches, from the source down, as on the Gauges tab. A stretch of the Blackwater includes the smaller streams that join it there.
Within 3 km of one of the Blackwater’s gauges in a straight line, but the river map cannot say whether their water reaches it.
3 storm overflows are traced upstream of Ower, the Blackwater’s lowest gauge on the river map: on the Blackwater itself, on its gauged tributaries, and on smaller streams that join above there.
Official figures for 2025, for the overflows traced upstream of Ower: 161 spills over 2,187 hours in total, across all 3.
Each overflow is listed in the stretch above the first gauge its water reaches, from the source down, as on the Gauges tab. A stretch of the Blackwater includes the smaller streams that join it there.
A status is the water company’s own monitor: it says whether an overflow is discharging, never how much or why, and a spill does not by itself explain a change in a river level. A status older than two hours is shown as unknown. Annual figures are the official returns: 12/24-hour spills for England and Wales, overflow events for Scotland (Scottish Water counts differently, so the two cannot be compared). “No data” means the monitor produced no usable data that year, not zero. Overflows are placed on OS Open Rivers (edition 2026-04), which leaves out many small channels: an overflow the map cannot place may still drain here. Contains OS data © Crown copyright and database rights 2026. Sewage in Britain’s rivers →
Live status: © Thames Water storm overflow activity data, licensed under CC BY 4.0. Live status: © Anglian Water storm overflow activity data, licensed under CC BY 4.0. Live status: © Southern Water storm overflow activity data, licensed under CC BY 4.0. Annual figures for England: Environment Agency Event Duration Monitoring return, © Environment Agency copyright and/or database right, Open Government Licence v3.0.
Dated samples taken by the Environment Agency, not live readings. Results are published days to months after the sample is taken, and many points are sampled only a few times a year, or have not been sampled for years.
Sampled most recently, anywhere on these rivers and their streams:
22 sampling points on the River Blackwater and the streams that join it above Swallowfield Side Channel. 18 have a sample from the last 12 months; 19 have any sample banked.
| Where, from the source down | Sampling points | Newest sample |
|---|---|---|
| Above Tongham | 1 point0 sampled | none banked |
| Above Cove Hazel AvenueCove Brook · joins the Blackwater above Blackwater Bridge | 1 point0 sampled | none banked |
| Above Farnborough | 5 points | 9 Jul 2026 |
| Above Blackwater Bridge | 3 points | 24 Aug 2026 |
| Above BramshillRiver Hart · joins the Blackwater above Swallowfield | 5 points | 1 Sep 2026 |
| Above River Whitewater at Holdshot FarmRiver Whitewater · joins the Blackwater above Swallowfield | 1 point0 sampled | none banked |
| Above Eversley | 2 points | 1 Sep 2026 |
| Above Swallowfield | 4 points | 1 Sep 2026 |
29 sampling points on the River Blackwater and the streams that join it above Appleford Bridge, and below it. 11 have a sample from the last 12 months; 13 have any sample banked.
| Where, from the source down | Sampling points | Newest sample |
|---|---|---|
| Above COPFORD HALL FGS DUAL COMMSRiver Pant · joins the Blackwater above Stisted | 4 points2 sampled | 7 Sep 2026 |
| Above Stisted | 10 points5 sampled | 16 Sep 2026 |
| Above Appleford Bridge | 11 points5 sampled | 15 Sep 2026 |
| Below the lowest gauge | 4 points1 sampled | 3 Jul 2026 |
13 sampling points on the River Blackwater and the streams that join it above Ower, and below it. 6 have a sample from the last 12 months; 7 have any sample banked.
| Where, from the source down | Sampling points | Newest sample |
|---|---|---|
| Above Ower | 12 points6 sampled | 17 Sep 2026 |
| Below the lowest gauge | 1 point | 17 Sep 2026 |
England's samples only. Each count opens the list of those points, nearest first, with the date of each one’s latest sample (the gauge’s “Upstream of here” list).
FloodRadar does not grade these results: there is no overall score, and official river classifications are a separate dataset. A sample taken downstream of an overflow does not by itself show where anything in it came from. River connections and distances are traced on OS Open Rivers (edition 2026-04), which leaves out many small channels.
Water samples: Environment Agency Water Quality Archive, © Environment Agency and/or database right 2026, Open Government Licence v3.0.
Contains OS data © Crown copyright and database rights 2026.
FloodRadar helper · beta