A predominant cause of water pollution in India is the discharge of large amount of untreated sewage of water into the water bodies. Hard water has major effects in day to day life and environment around such as it causes high blood pressure, cardiovascular diseases. It also affects fish culture in a way, excess of hard water can adversely affect the marine life. Hard water id often advised to use in industries because the hardness of waste water can be determined. Depending on hard water, soda water can be added to soften the water and to make it usable. Hence, to achieve all the aims a low cost hardness measurement device can be installed that can display the output on real time platform also.Water recycling has now become an important parameter as approximately 135lpcd of water is given about by a residential complex daily. When this waste water is given out, it leads to pollution of agricultural land, can spread diseases also. Hence, recycling means to check contamination of water. This can be done manually and automatically as well. But, if it is done automatically, errors can be avoided and accuracy can fetched. This led to an idea of developing a Hardness and Conductivity monitoring sensor.

What it does

  1. Automatic and Manual caliberations.
  2. Avoid errors.
  3. Good accuracy.

How I built it

The Arduino boards are used in order to collect the data from the system and take the action as the outputs. First, we have stepped down the 230VAC into DC voltage. The output voltage is set to 5V since, the current sensor is capable of sustaining 0-5V DC voltage. This stepped down 5V is given to the AC712. Because we want to calibrate the current flowing through the electrodes, the sensor is connected in series with the electrode. The voltage difference should be across two terminals in order to measure current in series. There are two ways to calibrate conductivity sensors. The sensor can be calibrated against a solution of known conductivity or it can be calibrated against a previously calibrated sensor and analyser. Normally, the sensor should be calibrated at a point near the midpoint of the operating range calibration changes the cell constant. To find the conductivity, below are the steps to be followed- To find the resistance- R=V/I To compute the conductance- G=(1/R)Mho To measure conductivity- Y=K*G 1. Once we know the conductivity of the process fluid, we can easily figure out the conductivity of any process fluid.

Challenges I ran into

  1. Testing different water samples
  2. Cloud Computing
  3. Sensor Caliberating

Accomplishments that I'm proud of

  1. Once we know the conductivity of the water, we can easily predict the status of hardness.

  2. The system uses open source software.

  3. Real-time automatic and continuous monitoring.

  4. Data is available in control rooms as well as on mobile phones.

  5. Notification alert when certain level is crossed.

What I learned

  1. How to code Arduino.
  2. How to interface sensor with microcontroller.
  3. Cloud Computing


  1. To develop a wireless sensor network for hardness and conductivity.
  2. To identify the sources of waste water.
  3. Notification to be given to the user and government authority also.
  4. To install similar sensors at different locations and collect data simultaneously from all the locations.

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