Privacy Policy
Last updated : 6 November 2026
Hydravia is built to work without an account and without a server. Almost everything stays on your phone. This page sets out exactly what stays local, the few cases where something is sent to a third party, and why.
1. Who is responsible
The app is published by Nicolas Meuwly, as a private individual, at Route de Fétigny 11, 1482 Cugy FR, Switzerland. For any question about your data, write to contact@hydravia.app.
2. What stays on your phone
The following is stored in a local database on your device only. It is never transmitted to us and never backed up to our servers, for the simple reason that we do not run any.
- Your weight, used to compute your daily goal.
- Your active hours (wake, sleep) and your reminder interval.
- Your intake history: every amount, with its date and time.
- Your preferences: whether reminders are on, which apps you selected for the lock.
If you use the Apple Watch app, your iPhone sends your watch today’s total, your goal, your favourite amounts and your hours, and your watch sends back the water you log on it. This exchange goes straight between your two devices, with no server involved, and your watch only keeps the current day.
You can erase your intake history at any time from Settings → Data → Delete history. Deletion is immediate and permanent. Uninstalling the app removes all of this data, settings included.
3. Location and weather
If you grant location access (only while using the app), and only in that case, Hydravia reads your location to look up the outside temperature, which slightly adjusts the recommended dose in hot weather. The coordinates are rounded to about 1 km before anything is sent.
Those rounded coordinates are sent to Open-Meteo (open-meteo.com), a weather service that requires no API key and ties the request to no profile. As with any internet connection, Open-Meteo also receives your device's IP address. Hydravia does not retain your location: it is used for the request, and only the resulting temperature is held in memory for 30 minutes.
If you decline the permission, the app works normally: dose calculation simply ignores the weather.
4. Screen Time and app blocking
On iOS the lock is built on Screen Time (Apple's Family Controls framework). Apple deliberately keeps this API sandboxed: it lets Hydravia apply a block to apps you select yourself, without ever granting access to your usage statistics.
In practice, Hydravia cannot see which apps you use, or for how long. Your selection stays on your device, inside a system-managed container. You can revoke this permission at any time in iOS Settings → Screen Time.
5. Subscriptions
Payments are handled by Apple. We never see your payment details.
Your subscription status is checked directly with the App Store, on your device. No receipt, no identifier and none of your hydration data is sent to us.
6. What we do not do
- No user account, so no email address or password is collected.
- No advertising trackers and no behavioural analytics SDK.
- No selling or sharing of data for commercial purposes.
- No advertising profiling and no cross-app tracking.
7. Recipients at a glance
| Recipient | Data sent | When |
|---|---|---|
| Open-Meteo | Rounded coordinates (~1 km), IP address | Only if you allow location access |
| Apple | Payment and subscription data | Only when purchasing or restoring |
8. Your rights
Under the GDPR you have rights of access, rectification, erasure, restriction and portability over your personal data. Because Hydravia holds no database about you, most of these rights are exercised directly on your phone: your data is on your device, and you can view or delete it whenever you want.
For any request about your data, write to contact@hydravia.app. You also have the right to lodge a complaint with the data protection authority in your country.
9. Children
Hydravia is not directed at children under 13 and does not knowingly collect their data.
10. Changes
This policy may change as the app evolves. The last updated date appears at the top of this page; for any significant change we will say so in the app.