Full & Low Water Tank Alarm Circuit Using 555 Timer Ic

💧 Are you tired of water overflowing from your overhead tank or running out of water at the wrong time? A Full & Low Water Tank Alarm Circuit using 555 Timer IC is the perfect DIY solution to ensure efficient water management. This smart circuit not only alerts you when the tank is full but also when the water level is running low. With a simple momentary switch to turn off the alarm, it is not necessary to turn on and off the device.

🌟 Introduction: Why You Need a Water Tank Alarm Circuit

Water is precious, and uncontrolled overflow leads to unnecessary wastage. The water overflow and low-level alarm circuit is designed to produce an audible alert whenever the tank is full or nearly empty. By using the versatile 555 Timer IC, this project ensures accurate water level detection in overhead tanks, swimming pools, underground sumps, aquariums, or fountains.

👉 Whether you want to prevent overflow, detect low water levels, or monitor water flow, this circuit is versatile enough to handle it all. It comes with a power indicator LED, full-tank LED indicator, and a loud buzzer. Plus, you can silence the alarm anytime with a simple press of the switch.

Circuit Diagram

⚙️ How the Full & Low Tank Alarm Circuit Works

• When the water level reaches the top, the circuit triggers the buzzer 🔔 and turns on the red LED to indicate overflow.
• When the water level is low, the circuit alerts you with the same alarm function, preventing your tank from going dry.
• The momentary switch lets you mute the alarm without cutting power.
• Sensors (metal probes & float switches) detect the water level inside the tank.

This setup can be powered using a 9V–12V transformer (200–500mA) or a 12V SMPS adapter. You can also customize the alarm sound by replacing the buzzer with a musical buzzer or a recordable chip.

🛠️ Parts Required

• Bridge Rectifier (DB1): W04 / DB107
• Transformer: 9V–18V AC, 200–500mA or a 12v SMPS Module
• Capacitors:
  • C1 – 220µF / 40V
  • C2 – 0.001µF (102)
• Diode: 1N4007
• Resistors (¼ W):
  • R1, R5 – 4.7KΩ
  • R2, R3 – 470KΩ
  • R4, R6 – 2.2KΩ
  • R7 – 22KΩ
  • R8 – 33KΩ
• Transistors: Q1, Q2 – BC547
• Buzzer: 3V–24V DC (continuous or intermittent)
• LEDs:
  • L1 – Green ✅ (Power ON)
  • L2 – Red ❌ (Tank Full/Low/Flow)
• Switch: Normally Open (Momentary Push Button)
• Sensors: Contact-type SS metal sensor/ Normally Open Float Switch
• ICs:
  • U1 – 7812 (for 12V+ supply)
  • U2 – 555 Timer IC

Full And Low Tank Alarm Video

Low Tank Alarm Video

💡 Applications of the Circuit

✔️ Overhead water tanks in homes 🏠
✔️ Underground sumps & borewell systems 💦
✔️ Swimming pools 🏊
✔️ Aquariums 🐠
✔️ Fountains ⛲

🎯 Benefits of This Circuit

• ✅ Prevents water wastage due to overflow
• ✅ Alerts you before tank runs dry
• ✅ Simple and low-cost DIY project
• ✅ Works 24×7 without supervision
• ✅ Customizable alarm (musical / recordable)
• ✅ Works as a low tank alarm
• ✅ Can be used as a water flow alarm