This page answers the questions that come up most often about Aquifer. If yours is not here: app@goswami.de. General matters are on the support page, data handling in the privacy policy.
Best written from inside the app: Settings → Contact. App version, iOS version and device are then already in the message.
During setup Aquifer suggests a goal derived from your body weight and how often you train: roughly 30 ml per kilogram, plus an allowance per workout. The result is rounded to 100 ml and kept between 1.0 and 3.5 litres.
It is a starting point, not medical advice. You can set your own figure at any time under Settings → Daily goal.
Under Settings → Glass sizes you decide which sizes appear as quick actions on the Today screen — matching your own glass, mug or bottle. Ones you do not need can be switched off. For a one-off amount, adjust it on the entry itself.
Under Settings → Unit you can switch between millilitres and ounces. Existing entries are converted along with it; nothing is lost.
Tap the entry in your history to change its amount or time, or to delete it. The day's total, your streak and the statistics are recalculated from there.
Aquifer works with exactly one Health field: water. Under Settings → Apple Health you choose the direction:
Off — no exchange at all. Write only — your entries go into Health, other apps' entries are not read. Both — Aquifer writes and additionally shows what other apps have logged as water today.
Duplicates — because a second app reported the same glass, say — can be merged on that same screen. If that does not help, Sync Health again re-runs the comparison. Permissions can be withdrawn at any time in the Health app under Data Access & Devices → Aquifer.
Aquifer has its own watch app and a complication for the watch face. A glass logged on the watch is queued and still delivered later if your iPhone is out of range — nothing is lost, it may just take a moment.
In the other direction the iPhone only ever sends the current total; a missed update is simply superseded by the next one. If the watch shows nothing for a while, open the app once on both devices.
Under Settings → Reminders you can pick an interval — every two hours, for example. If nothing arrives, check the iOS settings under Notifications → Aquifer. Reminders are scheduled locally; there are no push servers.
Under Settings → Data → Delete all data you remove entries, history and streak for good. Whatever Aquifer has already written to Apple Health stays there — delete that in the Health app under Data Access & Devices → Aquifer.
No. There is a voluntary tip — one-off, no subscription, and it unlocks nothing. Billing and refunds are handled by Apple: reportaproblem.apple.com.