The water demands of plants in a greenhouse can vary significantly, and can require frequent attention if watered by hand. A few days of absence or inattention can be disastrous. This simple control system can ensure that water is kept up to one or more planters, limited only by the water that can be delivered down a 5mm pipe.

This float valve can be connected by 5mm dia pipes typically used in small watering systems

This simple device requires only the most basic assembly (insertion of the lever arm over the top of the float), is robust and reliable, and works as a result of the soft resilience of the double sided adhesive tape used to make a seal. The float acts on a long lever arm to push the seal up against the incoming water pipe to control the rate of entry of new water.

A small piece of 1mm thick double sided self adhesive tape, approx 5mm x 10mm, is required to attach to the lever arm to make the seal. Note that the free side of the self adhesive tape should be coated with talc or similar in order to eliminate its stickiness.