Welcome to the
World of LUCY®


User Manual


Thank you for choosing LUCY®. Find out more about the installation and basic operation of your LUCY® Smart Cap.


The LUCY® UV-C purification function deactivates up to 100 % of potential contaminants in drinking water. The water is purified without the use of any chemicals and your bottle remains clean and odourless. This means that UV disinfection is a reliable and harmless way of killing viruses, bacteria and germs of all kinds.


Thanks to a sensor in your LUCY® Smart Cap, your water consumption can be easily recorded and tracked in the waterdrop® Hydration App. Your LUCY® Smart Cap can save your progress directly in the cap before syncing it with the app. So don’t worry about losing data because everything is recorded directly on your LUCY® Smart Cap.


Your LUCY® Smart Cap also reminds you to drink water by blinking in regular intervals, in case you haven’t reached your daily goal – directly in the app but also on your LUCY® Smart Cap itself. You decide how often and where you want to be reminded. You can easily adjust this feature at any time in the settings of your app.


  • Do not fill your bottle too full so that the LUCY® Smart Cap sensor does not protrude into your drink and can measure accurately. 
  • Close your bottle after refilling it or drinking from it so that the LUCY® Smart Cap can detect the new volume. 
  •  Do not fill your bottle with hot drinks, as the LUCY® Smart Cap sensor will fog up and no longer be able to measure accurately. 
  • Use the UV-C cleaning only for water. If you want to use a microd rink or microtea, throw it into your bottle after the cleaning process has finished.  
  • Do not clean your LUCY® Smart Cap in water. It is best to clean your LUCY® Smart Cap with a damp cloth on the outside and to use a cotton bud for cleaning the thread. 


Step 1: Download the waterdrop® Hydration App
Download the waterdrop® Hydration App in the App Store or Google Play Store.

Step 2: Using the waterdrop® Hydration App
If you already have a waterdrop® Club account, you can log in using your usual log-in details, or register and set up a new account. When you open the app for the first time, you will be asked for some information about yourself that defines your daily water consumption.

Step 3: Connecting the LUCY® Smart Cap to the waterdrop® Hydration App

  • After answering the aforementioned information, the app will ask you if you have a LUCY® Smart Cap and would like to connect it. If you no longer see this view, you can also click on the LUCY® symbol in the “Drink” menu or click on “Connect LUCY” in the settings.
  • Connect LUCY® to a suitable power source (USB power supply, computer, ...) using the USB cable provided. If a pop-up appears asking whether waterdrop® is allowed to use your Bluetooth connection, please click “OK”.
  • Next, press the button on your LUCY® until the waterdrop® logo starts to flash blue and select “Connect LUCY” in your app at the same time. If another pop-up appears on your smartphone asking if you would like to connect to a Bluetooth device, please accept. If the connection attempt was successful, LUCY® will now light up blue continuously for a short period of time.
  •  Select the waterdrop® bottle with which you want to use your LUCY® (you can change this at any time in the settings).
  • Now we would like to ask you to calibrate your empty bottle, i.e. to measure it so that the tracking of the water consumption and the LUCY® UV-C cleaning work properly. To do so, please place your empty bottle on a flat surface and tap “Start Calibration”. Please note that if you change your bottle, you will need to calibrate it anew.
  • Your LUCY® Smart Cap is now ready for use. Take a short tour through the world of the LUCY® Smart Cap in the app to get to know the functions even better.


Your LUCY® has a touch sensor (referred to as “button”) that provides several features. Here is a brief overview:

Connected to a power source

  •  By pressing and holding the button, you can activate the “pairing mode” of LUCY® to connect it to a smartphone. The waterdrop® logo flashes blue as soon as LUCY® is ready to connect and lights up solid blue for a few seconds when connected. 

Not connected to a power source 

  • A short press of the button indicates the battery charge level of LUCY®. The number of illuminated petals on the waterdrop® logo indicates the current battery status of LUCY®. If all 4 petals light up, your LUCY® is fully charged, the fewer petals light up, the weaker the battery level. 
  • Press and hold the button to activate the LUCY® UV-C cleaning function. The waterdrop® logo now rotates white and shows you the progress based on the petals. 

Further signals from LUCY®

LUCY® flashes light green twice 

Drinking quantity has been measured successfully

LUCY® flashes red twice 

Drinking quantity was not measured successfully

LUCY® flashes white several times

You are being reminded to drink

LUCY® flashes green for approx. 5 seconds 

UV-C cleaning has been carried out successfully

LUCY® flashes red for approx. 5 seconds 

UV-C cleaning could not be carried out 

LUCY® is connected to a power source:

Individual petals light up and “breathe”.

LUCY® is charging and indicates the charging progress by the amount of petals that light up.


The LUCY® Smart Cap does not connect to my smartphone
If you have problems connecting your LUCY® Smart Cap to your smartphone, we recommend that you start the connection process from the beginning. To do this, it is best to delete the LUCY® Smart Cap from your Bluetooth devices in the smartphone settings and make sure that it is not connected in the app itself. If required, click on "Disconnect LUCY" in the app settings. You can then click on "Connect to LUCY" on the drink screen and should be guided through the connection process. When establishing a connection, it is important that LUCY is connected to a power source throughout that process. Simultaneously press the "Connect to LUCY®" button in the waterdrop® Hydration App and press the button for 3 seconds until LUCY® flashes blue. Sometimes this may require another attempt. If this Bluetooth connection does not work directly, please click on "Try again" and press the button on your LUCY® Smart Cap until it flashes blue. If the LUCY® Smart Cap subsequently lights up blue for some time, it has been successfully connected.

Cleaning LUCY® properly
The best way to clean LUCY® is to use a damp cloth on the outside and a cotton bud on the thread. Never hold LUCY® under running water or immerse it in water, as LUCY® is an electronic device and should be treated as such.

The LUCY® Smart Cap regularly loses the connection to my smartphone.
Don't worry, this is not a problem, as the LUCY® Smart Cap does not need a continuous Bluetooth connection with your smartphone to properly measure your drinking progress. The LUCY® Smart Cap has its own log, which allows it to store your drinking progress and synchronise the data stored on your LUCY® Smart Cap with the waterdrop® Hydration App on your mobile phone the next time you connect.

My hydration progress is not immediately displayed in the app.
The synchronisation of your LUCY® Smart Cap and your waterdrop® Hydration App does not always happen in real time and it may therefore take a moment for your drinking progress to be transferred from your LUCY® Smart Cap to your smartphone. If it takes several minutes, it may also help to close the waterdrop® Hydration App completely and open it again. Don't worry though, because the LUCY® Smart Cap has its own log, which allows it to store your drinking progress and synchronise the data stored on your LUCY® Smart Cap with the waterdrop® Hydration App on your mobile phone the next time you connect. You should also be aware that your LUCY® Smart Cap can only measure your drinking progress at certain intervals and that very small sips may not be noticed directly but only measured later, together with a larger drinking amount.

The UV-C purification feature does not work.
There are several reasons why the LUCY® UV-C purification feature could not work. Your LUCY® Smart Cap may not be sufficiently charged to carry out the UV-C purification. To check this, simply press the button on your LUCY® Smart Cap: you can easily read the current battery status by looking at the number of petals of the waterdrop® logo that are lit up in white. If the waterdrop® logo lights up red, the LUCY® Smart Cap needs to be charged. Make sure that you use the cable supplied to charge your LUCY® Smart Cap. If the bottle you use your LUCY® Smart Cap with stands on an uneven surface, is moved, bumped or shaken during the cleaning process, the process is likely to be interrupted and must be restarted. In addition, the LUCY® Smart Cap is equipped with a thermal sensor. If you have started several cleaning cycles in quick succession, the device may become too warm. Give it a little time to cool down and then try again.

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