HYDR8 wearable tells you when to drink water — and it’s not just a smartwatch

A developer known as Ayushmaan has built a prototype wearable called HYDR8 that alerts users when they need to hydrate. The idea came from personal experience: the creator would get deeply focused on work, ignore his water bottle for hours, and later end up with a headache and a full bottle of untouched water. Phone reminders, he says, were quickly dismissed in irritation.

HYDR8 is based on a XIAO ESP32-C3 microcontroller. The wearable tracks heart rate, blood oxygen saturation, skin temperature, as well as ambient temperature and humidity. It also learns the user's personal resting baseline values over time.

Using all this data, the device generates a heat and hydration stress score ranging from 0 to 100. Based on the score, HYDR8 provides specific actionable advice: sometimes it tells the user to "drink water," other times it suggests "find shade." The wearable itself is somewhat bulky but keeps things simple — it only shows the time and a message when action is needed. The ESP32 powers a full dashboard accessible on the user's phone.

The creator emphasizes that HYDR8 is not a medical device — it is an experimental prototype. It cannot directly measure how hydrated a person is; instead, it estimates hydration stress. For those who prefer not to wear a device, an alternative exists: a smart straw equipped with a tiny turbine flowmeter and a Hall effect sensor that records the volume of liquid sipped and detects whether the user is drinking too little.