Hattie Knows: Wild Swim UK

Should I swim here, right now? Hattie answers in two seconds.

We check what's upstream of you, factor in the tide, and override the
verdict when there's an active flood warning. Every UK water company.
Every regulator. Free safety check-in. Free everything — no
subscription, no ads, no tracking.

We walk the river network, not just a circle.

Other apps show every sewage discharge within 5 km of your spot. We
walk the river network from where you're swimming, 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 every UK swimmer's phone.

iPhone. Apple Watch. Android. Web at wildswim.hattieknows.com. Same
verdict, same reason copy, all free. Glance widget shows your verdict
on the home screen so you don't even open the app.

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. The
app opens your own Messages — we never send a message on your behalf
or contact emergency services automatically. The "Need help" button
opens Android's emergency call dialog. Safety stays free, always.

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 verdict 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, unlimited saved spots, the full
Journal history, the Year-in-Cold recap, the home-screen widgets — is
free at launch. Built and funded independently. Not partnered with a
water company.

Built in the UK. Independent. Ad-free. Not funded by a water company.

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