The Unpowered Drip Irrigation Clay Pot Controller is used for DIY automatic measured  irrigation.  To operate the controller a minimum water supply pressure of one metre head (10 kPa) is required.
 
Installation of the Unpowered Drip Irrigation Clay Pot Controller:
Select a drip irrigation zone where all the plants in the zone have the same irrigation requirement.
Select a typical dripper and replace it with a subsurface clay pot.
Connect the clay pot to the controller.
Connect a dripper inside the controller.
Connect the water supply for the zone to the inlet of the controller (between 10 kPa and 800 kPa).
Connect the irrigation zone to the outlet of the controller.
Fill the controller with water until the float is partially covered.
Turn on the water supply and all the plants will be watered automatically without power.
 
Key features:
 
Unpowered (no batteries, no solar panels, no electronics, no computers, and no WiFi)
Use for gravity feed or pressurised irrigation
Use for PC (pressure compensating) drippers or NPC (non pressure compensating) drippers
Use for subsurface or surface drip irrigation
Use for drip tube or drip tape
The water supply pressure should be between 10 kPa and 800 kPa 
The water usage is controlled by the demand from the plants
The discharge from each dripper during an irrigation event is the same as the on-demand discharge from the subsurface clay pot since the previous irrigation event
The water usage increases significantly during a heat wave
With a continuous water supply, you can leave your irrigation application unattended for months on end