Terracotta is porous and so the water level in the terracotta pot falls as water seeps through the terracotta. A float inside the pot floats on the water. When the water level reaches the low level, a magnet inside the float activates the valve so that the valve opens and the irrigation starts. During the irrigation event a control dripper drips water into the pot and the water level rises. When the water level reaches the high level, the magnet inside the float disengages from the valve so that the valve closes and the irrigation stops.

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The Unpowered Terracotta Valve is suitable for automatic sprinkler irrigation or drip irrigation. The valve operates in the pressure range 10 kPa to 800 kPa. The irrigation frequency responds automatically to the on-site prevailing weather conditions (namely, evaporation and rainfall). 

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During an irrigation event, the control dripper replaces the water that has seeped through the terracotta since the previous irrigation event. This volume is called the control volume. The Half inch Unpowered Terrcotta Valve has a control volume between 77 ml and 333 ml.

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The Unpowered Terracotta Valve is a game-changer for automated gravity feed irrigation from a rainwater tank without using a pump.

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Key Features​

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1. Unpowered (no batteries, no solar panels, no electronics, no computers, and no WiFi)

2. Water supply pressure 10 kPa to 800 kPa

3. Half inch inlet and outlet

4. Use for sprinkler irrigation or drip irrigation

5. Use for gravity feed or pressurised irrigation

6. Adjust the water usage rate by adjusting the control dripper

7. Adjust the interval between irrigation events by adjusting the float

8. Responds automatically to on-site evaporation and rainfall

9. The irrigation frequency increases significantly during a heat wave

10. Install above ground or in ground

11. For in ground installation the controller responds automatically to plant transpiration

12. Provided the same drippers are used throughout the irrigation application (including the control dripper), the water usage rate is independent of the water supply pressure

13. Irrigate directly from a rainwater tank without using a pump

14. Water in the terracotta pot is protected from debris, algae, mosquitoes and thirsty animals

15. Simple, unpowered, and low tech, and therefore fewer things can go wrong

16. Leave your irrigation application unattended for weeks on end