Hattie Knows: Wild Swim UK

Upstream-aware sewage alerts: we walk the river network from your spot, not just a 5km circle. Plus tides, bathing-water ratings, and a free safety check-in. Free to use.

Should I swim here, right now?

Four apps open before you get in. Sewage checker. Tide times. Wind forecast. A Facebook group to ask if it's any good. Hattie Knows Wild Swim puts it all into one honest verdict.

We don't just check what's near you — we check what's upstream.

Other apps show every sewage discharge within 5 km. We walk the river network from your spot, up to 250 segments upstream, and only count discharges that can actually reach you. At tidal rivers we factor in the tide — on a rising tide we widen the window, on a falling tide we narrow it. It's how water actually moves.

Every UK water company. Every regulator.

Live discharge feeds from all 12 UK water companies (11 live, 1 pending). Bathing-water classifications from the Environment Agency, Natural Resources Wales, SEPA and DAERA. Flood warnings from the EA and NRW with full polygon geometry, not just a point alert.

Now on Apple Watch.

Your verdict, your conditions, your check-in countdown — on your wrist. Leave your phone on the beach. Tap "I'm out" from the water. Complications keep your verdict on the watch face all day.

Your swim, not the abstract one.

Tell us your cold tolerance and how long you'll wait after a sewage discharge. The Planner re-scores every hour of the next seven days against your preferences — not "the best window" but "the best window for you."

Free live check-in.

Tell Hattie where you're swimming and how long. If you don't come back, we nudge you to message your buddy with your last location. No subscription. No paywall. Safety stays free.

A journal that remembers the water.

Your Year-in-Cold. Your coldest dip. Your week-streak. Every swim tied to that day's temperature and the state of the sewage, so next May you'll know what this May felt like.

We show our working.

Every reading on the hero card has a freshness timestamp and a named source. If a feed is down, we say so on the Water Companies status page. No black boxes. No "AI." Just live data, honestly filtered.

Free for everyone. No subscription. No ads. No tracking.

Every feature in this listing — the upstream-aware verdict, the 7-day personal Planner, the live check-in, the Apple Watch app, unlimited saved spots, the full Journal history, the Year-in-Cold recap, the lock-screen widgets — is free at launch. Built and funded independently. Not partnered with a water company.

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