Small and Large Terracotta Valve 

It is recommended that you watch the YouTube video Terracotta Valve


The control dripper drips water into the terracotta pot

Small Terracotta Valve showing float and water level

The float for the Small Terracotta Valve is adjustable

Large Terracotta Valve showing float and water level

The float for the Large Terracotta Valve is adjustable

Terracotta is porous and so the water level in the pot falls as water evaporates from the outside surface of the pot. 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.

The Terracotta Valve is an unpowered irrigation valve suitable for automatic sprinkler irrigation or drip irrigation. The valve operates in the pressure range 10 kPa to 800 kPa. The valve does not require an irrigation controller. Each valve is self-controlled whereby variations in the irrigation frequency are automatically controlled by the on-site prevailing weather conditions (namely, evaporation and rainfall).

During an irrigation event, the control dripper replaces the net volume of water that has evaporated since the previous irrigation event. This volume is called the control volume. The Small Terrcotta Valve has a control volume between 90 ml and 275 ml. The Large Terracotta Valve has control volume between 400 ml and 2300 ml.

By using the Small or Large Terracotta Valve with the appropriate control dripper, you can irrigate directly from the rainwater tank by gravity feed without using a pump. Furthermore, the volume of water discharged by each irrigation dripper will be independent of the water level in the tank. The Terracotta Valve is a game-changer for automated gravity feed irrigation from a rainwater tank without using a pump.

Key Features

  1. Completely automatic

  2. No electricity required (no batteries, no solar panels, no electronics, no computers, and no WiFi)

  3. No timer required

  4. Smart irrigation – the irrigation is controlled by the prevailing weather conditions

  5. Valve operates in the pressure range 10 kPa to 800 kPa

  6. Use for both gravity feed and pressurised irrigation

  7. Use with PC (pressure compensating) drippers and NPC (non pressure compensating) drippers

  8. Use for sprinkler irrigation, drip irrigation, or porous hose irrigation

  9. Adjust the water usage by adjusting the control dripper

  10. Adjust the irrigation frequency by adjusting the float

  11. Adjusting the water usage does not affect the irrigation frequency, and adjusting the irrigation frequency does not affect the water usage

  12. The water usage and irrigation frequency are directly proportional to the net evaporation rate (evaporation minus rainfall)

  13. Responds appropriately to an unexpected heat wave

  14. When it rains, water enters the terracotta pot and delays the start of the next irrigation

  15. If you are using the same drippers throughout the irrigation application including the control dripper, the water usage is independent of the pressure

  16. You can irrigate directly from a rainwater tank without using a pump

  17. Uses less water without affecting the yield

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

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

  20. Provided you have a continuous water supply, you can leave your irrigation application unattended for months on end

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Large Terracotta Valve