Managing water tanks manually can be inconvenient and often leads to overflow or dry running of the pump. In this project, we build a simple, reliable, and low-cost Automatic Water Pump Controller using float switches and a relay, without using any microcontroller or IC.
This system is perfect for homes, small buildings, and DIY enthusiasts who want a fully automatic water level control system without programming.
What is an Automatic Water Pump Controller?
An automatic water pump controller is a system that automatically controls a water pump based on the water level in tanks.
In this project:
- The pump turns ON automatically when the overhead tank is low
- The pump turns OFF automatically when the tank is full
- It also prevents dry running using an underground tank float switch
Required Components
- Float Switch (2 pcs)
- 5V / 12V Relay module
- 10k Resistor
- LED Indicators with 1k Resistors (optional)
- 5V/12V SMPS Power Supply
Here, if you use the 12V DC supply, then use a 12V relay module, and for the 5V supply, use a 5V relay module.
Tutorial Video on Automatic Power Switching with Relay
In this tutorial video, I have explained the circuit and how the automatic water pump controller works using just float switches.
Circuit of the Automatic Water Pump Controller
For an Active-HIGH relay module, refer to the circuit on the left, and for an Active-LOW relay module, refer to the circuit on the right.
Each float switch has three wires. The black wire is common. When the float is in the down position, the black and green wires are connected, and when the float is in the up position, the black and red wires are connected.
Working Principle of the Pump Controller Circuit
This project works using a simple electrical logic system built with float switches and a transistor-driven relay.
1. Underground Tank Float (Dry Run Protection)
The float switch installed in the underground tank ensures that the pump runs only when water is available.
- When water is present → Float switch is closed (Black & Red)
- When tank is empty → Float switch opens (Black & Green connected)
👉 If the tank is empty, the circuit stops the pump immediately to avoid damage.
2. Overhead Tank Float (Overflow Protection)
This float switch is placed at the maximum level of the overhead tank.
- Tank not full → Float switch remains closed (Black & Green connected)
- Tank full → Float switch opens (Black & Red connected)
👉 This stops the pump automatically and prevents water overflow.
3. Transistor Relay Driver
The output from both float switches is connected to the control pin of the relay module
- When both floats are closed → Relay turns ON
- Relay activates the pump
When any float opens:
- Relay deactivates
- Pump stops
4. Relay and Pump Control
The relay acts as a switch to control the pump:
- Relay ON → Pump ON
- Relay OFF → Pump OFF
For high-power pumps, it is recommended to use a contactor controlled by the relay.
LED Indicators (Optional but Useful)
You can add LEDs to monitor system status:
- 🔵 Blue LED indicates Overhead Tank is Full
- 🟡 Yellow LED indicates the Underground Tank is Empty
Safety Tips
- Always use a contactor for high-power pumps
- Keep AC and DC wiring separate
- Use proper insulation and enclosures
- Add a fuse or MCB for protection
Applications of the Auto Pump Controller
This water pump controller project can be used in:
- Home water tank automation
- Borewell systems
- Overhead tank control
- Small industries
- Agricultural water systems
Conclusion
This Automatic Water Pump Controller using float switches and relay is a simple yet powerful solution for water management. It eliminates manual effort, prevents water wastage, and increases the lifespan of your pump by avoiding dry running.
Since the Pump Controller does not use any IC or microcontroller, it is highly reliable, beginner-friendly, and perfect for long-term use.
