How to build a drinking water TDS meter with arduino, are there any sensors ?

I want to build a TDS meter to show its value on LCD screen on my DIY RO purifier, So i found the arduino can do that but i dont know which sensors to use and how to connect, can someone help me.


After a long research and executions by collecting all the sensors and working codes, I made a TDS sensor for my RO purifier using ESP8266 and monitoring over blynk server. I am sharing the references which helped me, so others can use them. I built the diy Purifier from a YouTube video.
Circuit diagram and code:

google "tds sensor" for examples.

Since it all begins with the sensor you may want to look at something like this:

This considering an inexpensive hobby type TDS sensor. They do mention:

Input Voltage: 3.3/5V
Output Voltage: 0 ~ 2.3V
Working Current: 3 ~ 6mA
TDS Measurement Range: 0 ~ 1000ppm
Power indication LED
Connection Interface: Grove 4-Pin / XHB 2.54mm 2P