Privacy Policy
Last updated : September 2026
1. Introduction
This privacy policy describes how HydroZen collects, uses and protects your personal data.
2. Data collected
Advertising (Google AdMob)
When you consent to personalized ads, AdMob may collect :
- Advertising ID
- IP address
- Device information (model, OS version)
- App usage data and interactions
Analytics (Firebase Analytics / Google Analytics for Firebase)
To understand which acquisition channels bring users to HydroZen and how the app is
used, we collect analytics events when you consent :
- App install source and campaign attribution (UTM parameters from Play Store links)
- Automatic events : first open, session start, screen views, user engagement
- Custom events : app share initiated, in-app review flow requested/completed
- Device model, OS version, app version, locale, and a technical Firebase install identifier
No health data, precise location, or personal identifiers are ever included in these events.
Collection is gated on your consent choice in the GDPR message.
Crash diagnostics (Firebase Crashlytics)
To keep the app stable, we collect anonymous crash reports containing :
- Stack trace and cause of the crash
- Device model, Android version, and app version
- A technical Firebase install identifier (used to group crashes; not linked to any personal account)
No health, location, or advertising data is included in crash reports.
Weather (Norwegian Meteorological Institute — api.met.no)
When you enable weather-based hydration adjustment, your device’s approximate location
(latitude and longitude) is sent to api.met.no to retrieve the local temperature.
This coordinate is not stored on our servers.
Health & Fitness data (Health Connect)
This app requests access to the following Health Connect data types :
- Hydration — read/write to sync water intake
- Weight — read/write to calculate personalized hydration goal
- Exercise sessions — read to adjust goal based on workout intensity
- Steps — read to adjust goal based on daily activity
- Sleep sessions — read to adjust goal based on sleep quality
- Total calories burned — read to improve exercise-based goal adjustment
This data is :
- Read and/or written locally on your device via Health Connect
- Never transmitted to our servers
- Never shared with third parties
- Never used for advertising purposes
- Only used to provide the core features of the app
3. Purpose of data processing
| Data |
Purpose |
Legal basis |
| AdMob data |
Display ads |
Consent (GDPR Art. 6.1.a) |
| Analytics events |
Measure acquisition and usage |
Consent (GDPR Art. 6.1.a) |
| Crash diagnostics |
Detect and fix app crashes |
Legitimate interest (GDPR Art. 6.1.f) |
| Weather location |
Adjust daily hydration goal |
Consent, given by enabling the feature (GDPR Art. 6.1.a) |
| Health Connect data |
Core app functionality |
Consent (GDPR Art. 9.2.a) |
4. Health Connect — specific commitments
In compliance with Google Play’s Health Connect policy, we confirm that :
- Health data is only used to provide or improve the app’s health features
- Health data is never used for advertising, analytics, or data brokers
- Health data is never sold
- Health data access is limited to what is strictly necessary (data minimization)
- Data is deleted from the app when you delete your account or uninstall the app
5. Third parties
Google AdMob
Used to display ads in the app.
- Privacy policy : https://policies.google.com/privacy
- Opt-out : https://adssettings.google.com
Firebase Analytics / Google Analytics for Firebase (Google)
Used to measure acquisition (which channels bring installs) and aggregate usage.
Collection is denied by default and only activated once you grant consent through
the GDPR message. Data collected is limited to install source, session/screen events,
and a technical install identifier; no health, location, or personal data is included.
You can withdraw consent at any time from Profile → Manage Consent.
- Privacy policy : https://firebase.google.com/support/privacy
Firebase Crashlytics (Google)
Used to detect and diagnose app crashes so we can fix them.
Collected data is limited to stack traces, device/OS/app version, and a technical install
identifier; no health, location, or advertising data is included.
- Privacy policy : https://firebase.google.com/support/privacy
- Opt-out : Profile → Crash reporting
Norwegian Meteorological Institute (api.met.no)
Used to retrieve local weather data when you enable weather-based hydration adjustment.
Your device’s approximate coordinates are sent to api.met.no for each temperature lookup
and are not stored on our servers.
- Privacy policy : https://www.met.no/en/About-us/privacy
Health Connect (Android)
Local Android platform used to read/write health data.
- Privacy policy : https://support.google.com/googleplay/answer/12954039
6. Data retention
- AdMob data : managed by Google per their own retention policy
- Health Connect data : stored locally on your device, never on our servers
- Crash reports : retained for 90 days maximum
- Weather location : not stored on our servers; met.no’s own retention applies to their logs
7. Your rights (GDPR)
You have the right to :
- Access your personal data
- Correct inaccurate data
- Delete your data
- Withdraw consent at any time from the app settings
- Object to crash reporting at any time from Profile → Crash reporting
- Lodge a complaint with your local data protection authority (e.g. CNIL in France)
To exercise your rights regarding Health Connect data,
you can manage or delete it directly from the Health Connect app on your device.
8. Data security
We do not store your health data on any server.
All health data remains on your device and is protected
by Android’s Health Connect permission system.
9. Children
This app is not intended for children under 13.
We do not knowingly collect data from children.
10. Changes to this policy
We may update this policy periodically.
The “Last updated” date at the top will reflect any changes.
Continued use of the app after changes constitutes acceptance.
For any privacy-related questions :
contact@hydrozen.app