Simple Water Quality Analysis Using Arduino

An easy-to-build and low-cost water quality monitor.

Things used in this project

Hardware components

Arduino MKR1000

Jumper wires (generic)

Resistor 4.75k ohm

Gold-Plated Pin

Breadboard (generic)

Software apps and online services

Arduino IDE

Story

After I saw TDS measure circuit I am thinking if it possible use few parts to complete measure.

Here I try as below.

Hardware

Arduino MKR1000 * 1

4.7k ohm resistor * 2

Dupont Line * 3

2P 2.54mm connector Line * 1

2.54mm gold plated pin 2P * 2

Connection

See pictures and caption below.

connect resistor and wire on breadboard

combine 2P 2.54mm connector Line and gold plated pin

connect MKR1000’s A0/D2/D3 with Dupont Line

Software

Program with Arduino IDE and modify form example “Analog Input”

void loop() {
 // start
 digitalWrite(ledPin, HIGH);
 //port LL
 digitalWrite(port1, LOW);
 digitalWrite(port2, LOW);
 sensorValue1 = analogRead(sensorPin);
 delay(delaytime);
 //port LH
 digitalWrite(port1, LOW);
 digitalWrite(port2, HIGH);
 sensorValue2 = analogRead(sensorPin);
 delay(delaytime);
 digitalWrite(ledPin, LOW);
 //port HH
 digitalWrite(port1, HIGH);
 digitalWrite(port2, HIGH);
 sensorValue3 = analogRead(sensorPin);
 delay(delaytime);
 //port HL
 digitalWrite(port1, HIGH);
 digitalWrite(port2, LOW);
 sensorValue4 = analogRead(sensorPin);   
 delay(delaytime);
 Serial.print(sensorValue1);
 Serial.print(",");
 Serial.print(sensorValue2);
 Serial.print(",");
 Serial.print(sensorValue3);
 Serial.print(",");
 Serial.print(sensorValue4);
 Serial.println();
}

Result

Here I have one bottle clean water and one bottle non-pure water.

I collected three different data comparisons

1. Gold plated pin is out of water

2. Pin in clean water

3. Pin in non-pure water

Analysis

When pin in clean water, data is

“159, 434, 874, 601”

“163, 433, 873, 600”

“165, 436, 871, 598”

When pin in non-pure water data is

“159, 462, 876, 566”

“159, 465, 878, 564”

“158, 463, 878, 565”

Here the 1st and 3rd are close at each sample, 2nd and 4th have 25~30 count gap.

It is exactly what I want “can be used to distinguish water quality.”

Next step I need a TDS meter as standard reference.

=================================================================

update 2018/5/13

Today I increase the number of ADC sampling and use my home’s 4 different water test again.

RO water

Ground water

Tap water

Water outdoor

Bottle 1 is RO water.

Bottle 2 is groundwater.

Bottle 3 is tap water.

Bottle 4 is water outdoor.

Bottles

Test video as below

it seems that RO water ADC value have very different with other. WiFi-web-server function

I also add WiFi-web-server function to show data on explorer.

data on explorer.

Ro water

Ground water

tap waterwater outdoor

Here the sensorValue number mean

sensorValue0 port voltage is Low Low

sensorValue1 port voltage is Low High

sensorValue2 port voltage is High High

sensorValue3 port voltage is High Low

But since I change the pin the value order ( 2nd and 4th ) are not the same with first time test.

Schematics

TDS

Here yellow and black wire are test port.
Need a fixed distance.

TDS

Fzz file
Here yellow and black wire are test port.
Need a fixed distance.

Code

/*
  TDS 
  
  change from
  
  Analog Input
  created by David Cuartielles
  modified 30 Aug 2011
  By Tom Igoe
  This example code is in the public domain.
  http://www.arduino.cc/en/Tutorial/AnalogInput
*/

int sensorPin = A0;    // select the input pin for the potentiometer
int ledPin = 13;      // select the pin for the LED
int sensorValue1,sensorValue2,sensorValue3,sensorValue4;  // variable to store the value coming from the sensor

int port1 = 2;      // TDS port1
int port2 = 3;      // TDS port2

const int delaytime = 500; //delaytime for discharge
void setup() {
  // initialize serial:
  Serial.begin(115200);
  // declare the ledPin as an OUTPUT:
  pinMode(ledPin, OUTPUT);
  pinMode(port1, OUTPUT);
  pinMode(port2, OUTPUT);
}

void loop() {
  // start
  digitalWrite(ledPin, HIGH);
  
  //port LL
  digitalWrite(port1, LOW);
  digitalWrite(port2, LOW);
  sensorValue1 = analogRead(sensorPin);
  delay(delaytime);
  //port LH
  digitalWrite(port1, LOW);
  digitalWrite(port2, HIGH);
  sensorValue2 = analogRead(sensorPin);
  delay(delaytime);
  
  digitalWrite(ledPin, LOW);
  
  //port HH
  digitalWrite(port1, HIGH);
  digitalWrite(port2, HIGH);
  sensorValue3 = analogRead(sensorPin);
  delay(delaytime);
  //port HL
  digitalWrite(port1, HIGH);
  digitalWrite(port2, LOW);
  sensorValue4 = analogRead(sensorPin);   
  delay(delaytime);
  Serial.print(sensorValue1);
  Serial.print(",");
  Serial.print(sensorValue2);
  Serial.print(",");
  Serial.print(sensorValue3);
  Serial.print(",");
  Serial.print(sensorValue4);
  Serial.println();
}

/*
  WiFi Web Server

 A simple web server that shows the value of the analog input pins.
 using a WiFi shield.

 This example is written for a network using WPA encryption. For
 WEP or WPA, change the WiFi.begin() call accordingly.

 Circuit:
 * WiFi shield attached
 * Analog inputs attached to pins A0 through A5 (optional)

 created 13 July 2010
 by dlf (Metodo2 srl)
 modified 31 May 2012
 by Tom Igoe

 */

#include <SPI.h>
#include <WiFi101.h>


#include "arduino_secrets.h" 
///////please enter your sensitive data in the Secret tab/arduino_secrets.h
char ssid[] = SECRET_SSID;        // your network SSID (name)
char pass[] = SECRET_PASS;    // your network password (use for WPA, or use as key for WEP)
int keyIndex = 0;                 // your network key Index number (needed only for WEP)

int status = WL_IDLE_STATUS;

WiFiServer server(80);



int sensorPin = A0;    // select the input pin for the potentiometer
int ledPin = 13;      // select the pin for the LED
int sensorValue[4];  // variable to store the value coming from the sensor

int port1 = 2;      // TDS port1
int port2 = 3;      // TDS port2

const int delaytime = 50; //delaytime for discharge


void setup() {
  //Initialize serial and wait for port to open:
  // initialize serial:
  Serial.begin(115200);
  // declare the ledPin as an OUTPUT:
  pinMode(ledPin, OUTPUT);
  pinMode(port1, OUTPUT);
  pinMode(port2, OUTPUT);

  // check for the presence of the shield:
  if (WiFi.status() == WL_NO_SHIELD) {
    Serial.println("WiFi shield not present");
    // don't continue:
    while (true);
  }

  // attempt to connect to WiFi network:
  while (status != WL_CONNECTED) {
    Serial.print("Attempting to connect to SSID: ");
    Serial.println(ssid);
    // Connect to WPA/WPA2 network. Change this line if using open or WEP network:
    status = WiFi.begin(ssid, pass);

    // wait 10 seconds for connection:
    delay(10000);
  }
  server.begin();
  // you're connected now, so print out the status:
  printWiFiStatus();
}


void loop() {

  for(int i=0;i<4;i++)
  {
    sensorValue[i]=0;
  }
  for(int sampleCnt=0;sampleCnt<10;sampleCnt++)
  {
    // start
    digitalWrite(ledPin, HIGH);
  
    //port LL
    digitalWrite(port1, LOW);
    digitalWrite(port2, LOW);
    sensorValue[0] += analogRead(sensorPin);
    delay(delaytime);
    //port LH
    digitalWrite(port1, LOW);
    digitalWrite(port2, HIGH);
    sensorValue[1] += analogRead(sensorPin);
    delay(delaytime);
  
    digitalWrite(ledPin, LOW);
  
    //port HH
    digitalWrite(port1, HIGH);
    digitalWrite(port2, HIGH);
    sensorValue[2] += analogRead(sensorPin);
    delay(delaytime);
    //port HL
    digitalWrite(port1, HIGH);
    digitalWrite(port2, LOW);
    sensorValue[3] += analogRead(sensorPin);   
    delay(delaytime);
    
  }