This is a little bit hard project. But I will explain it in a simple manner.

How It Works--The Arduino turns the water pump ON/OFF by calculating the data received from the Ultrasonic Distance Sensor. If the data is a particular distance (In Code -first-Inches then cm) less from the sensor, then the Arduino turns the water pump ON. After turning it ON, it checks if the data is a particular distance (In Code - Inches) high from the sensor, the the Arduino turns the water pump OFF. Then measure PH of this water using PH-meter then abnormal value aware using buzzer.

Pump ON/OFF- Auto and Manual

How I made this project-- I was worried about the overflow of the water from my water tank. I loses a huge amount of water from it. So, I started thinking of a way to get rid of it. I came with an idea of making a system which controls the water pump.