This “automatic plant watering system with a PET bottle” is a simple possibility for you to save your plants from withering when your away for some time. For example, when you go for holidays and there´s no one home taking care of your plants. I use this gadget at work especially during Christmas holidays when there´s nobody in the office and watering the plants.

To use this system, you need just an additional PET bottle with the standard PCO 28 mm thread. The size doesn´t matter for the function but of course for the duration of the provided water supply for your plant. I recommend using a stable returnable bottle. These ones are not affected by the establishing vacuum inside the bottle during the watering process. The three big, splayed out pillars make the complete structure firm with the result that you don´t need to worry about dropping it down. For refill just unscrew the bottle and fill it at the tab.

The plant pot needs to be combined with a saucer with a maximum height of about 40 mm. The minimum is about 15 mm. If the saucer is much bigger than the pot, then the saucer can even be higher. The functional idea is copied from water dispensers for chicken. The end of water escape pipe has two holes: the lower and bigger one for water outlet and the upper one for air inlet. When the water level is below upper hole. Air will be inflowing through the pipe into the bottle and water is meanwhile flowing into the saucer. When the water level is reaching the upper hole the air inflow is blocked and no more water is flowing. Once the plant has consumed enough water that the level sinking below the upper hole the next watering event takes place. This is a little spectacle when the air bubbles are ascending in the bottle which is accompanied by some sound which normally makes you aware of that your plant is watered automatically.

To be sure that your system works properly you better use any type of sealing between the bottle and the pipe. You can either place something on the ground of the thread where there is a groove with an inner diameter of 21 mm, or you place something in between the turns of the thread, or on top of the thread where a chamfer is supporting your sealing. But you also can be lucky with a great printing quality where you don´t need a sealing. Your print has to be waterproof. If you are working with water soluble support material make sure your nozzle is not dripping.

This system is only applicable for helophytes. When your plant or flower doesn´t tolerate waterlogging please don´t use it otherwise your plant won´t survive. Please test your system while you still around. First to make sure everything works properly. Second to get to know how long one bottle of water is sufficient for your plant.