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Privacy Policy

Lutra — hydration tracking

Last updated: 20 August 2026

What the app stores

Everything below is entered by you, and all of it stays on your device:

• Your profile: weight, your answer to the question about physiological profile (including "pregnant" and "breastfeeding", or "prefer not to say", which is the option offered by default), activity level, climate, and your wake-up and bedtime hours.
• Your daily goal, whether calculated by the app or set by you.
• Your drink entries: amount, date, time and type of drink.
• Your progress: streaks, badges earned, your otter's outfit.
• Your reminder settings: whether they are on, and how many per day.

Where it is stored

It is written to the app's private storage on your device, protected by iOS encryption.

If you are signed in to iCloud, it is also synchronised through CloudKit, into your own private iCloud database. That database belongs to your Apple Account: it is not accessible to us. This is what lets you find your history again on a new iPhone by signing in to the same Apple Account. You can turn it off at any time in iOS Settings, under your iCloud account.

What the app does not do

• No analytics, no usage measurement, no statistics tooling.
• No advertising trackers, no advertising identifier, no cross-app tracking.
• No third-party libraries, no external SDKs.
• No data sent to any server, ours or anyone else's.
• No selling, no sharing, no transfer to third parties.

The privacy manifest shipped with the app declares this absence of collection and of tracking; Apple can verify it on every submission.

Reminders

Lutra's reminders are local notifications: they are scheduled by the app on your device, at the times you chose, and never pass through any server. You can decline them without losing access to anything, and turn them off at any time in iOS Settings or in the app.

Purchases

Subscriptions and the lifetime purchase are handled by the App Store. Payment, card details and the buyer's identity are managed end to end by Apple: we never see them. The app only asks iOS whether a valid purchase is active, and receives a yes or a no.

Apple's handling of that data is governed by Apple's own privacy policy.

Sharing

The app can compose an image summarising your progress. That image is only created when you ask for it, and it is not sent anywhere: it is handed to the iOS share sheet, where you alone choose the destination.

Health data

Lutra does not connect to Apple Health, and neither reads from nor writes to it.

The profile information you enter is used solely to calculate a hydration goal on your device. That goal is an indicative average, not a medical prescription: if you are unsure, or if a healthcare professional has given you a target, follow theirs — the app lets you enter it manually.

Deleting your data

• On the device: deleting Lutra removes all local data.
• In iCloud: the synchronised copy can be removed from iOS Settings, in the storage management section of your iCloud account.
• A single day: the app's settings let you erase the current day's entries.

Since no data ever reaches us, there is nothing to ask us to delete.

Your rights

The General Data Protection Regulation gives you rights of access, rectification, erasure, restriction and portability. These are normally exercised with the data controller — but in Lutra's case, no personal data is transmitted to us, so we hold no record concerning you. You exercise those rights directly, from your device: your data is visible in the app, editable in its settings, and deletable as described above.

Children

Lutra is not directed at children and does not knowingly collect any data concerning them. Since no information is transmitted, no child's data can reach us.

Changes

Any change to this policy will be published on this page, with an updated date. If a change were ever to introduce data collection — which is not planned — it would be announced in the app before taking effect.

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