Where to look?
The Alexa Waterlock skill can be found in Skills & Games in the Amazon Alexa app. This can also be found through the Amazon webstore here: geo Waterlock skill.
How to Install?
Select the geo Waterlock skill whilst in the Amazon Alexa app and tap the 'Enable to use' button, and you will be directed to a login screen, where you be prompted to login with your geo Waterlock credentials to link your account.
Once you have entered your login credentials successfully, you will notified that your account has been linked with the geo Waterlock skill.
Once your account has been linked, go back into the Amazon Alexa app and tap 'Discover Devices', which will allow you to configure the skill to be used for the devices in your Waterlock system.
Tap 'Devices' to view your Waterlock devices, where you will see your valve appear (for the example below, this has been named as "The Cave") and a new scene under Scenes (which is called 'Water, in this example).
After this, you will be able to assign commands to your Waterlock system. The commands can be found here: geo Waterlock skill.