Water Tank Levels by WiFi on Your Phone




About: I'm retired, living in Queensland Australia with my wife. These are my hobbies, pretty much full time now. Isn't it great to retire and actually pursue your real interests!

This instructable is entered in the "Wireless" contest. Please vote for me, Thank you

When I moved to a rural property in Australia I was faced with the fact my water supply was at the mercy of the Gods; rain from the sky to fill the tanks.

I had a capacity of around 30,000 litres across 2 concrete tanks and checking the levels meant climbing up a ladder, lifting a very heavy concrete cover and peering down into the damp darkness to estimate the levels.

Not much fun, inaccurate and time consuming, there must be an easier way.

Using Blynk and my WLAN was the answer, I could see at a glance the levels on my phone.

Check out Blynk here

Step 1: The Hardware

The standard HC-SR04 ultrasonic sensors are not waterproof, waterproof ultrasonic transmitter/receiver sensors to the rescue. These are the same units used on motor vehicles for reversing and hazard detection. These coupled to an ESP8266 NodeMCU WiFi board plus a small power regulator board make up the hardware.

These parts can be bought from AliExpress very cheaply (links below) or the supplier of your choice.

ESP8266 NodeMcu-V3-Lua-WIFI

Waterproof Ultrasonic Sensor

DC-DC 3.3v supply

Plus a waterproof box big enough to fit all the boards in.

Breadboard for testing

Link wires

LED color of your choice

Plug pack, 9 - 12VDC with Arduino UNO compatible type connector

Step 2: Wiring It Together on the Bench for Initial Testing

I used a breadboard for initial setup and testing.

For testing purposes this can run off the USB supply from your PC but in the field I used a small 3v3 regulated DC-DC converter supplied by a 9v plug pack. A 12v supply could be used with these converters. Use what you have laying around.

Plug the 2 ultrasound sensor boards directly into the breadboard and run 2 wires for each to the Arduino as below. Be aware these ESP12E boards run on 3.3 volts. They have a 5v input supply pin (VIN) and also run on the USB supply when connected to your PC. Do not supply more than 5 volts to the VIN pin if you use that.

Wire using male to female link wires:

Sensor1 ping to Arduino GPIO5 (D1)

Sensor1 echo to Arduino GPIO4 (D2)

Sensor2 ping to Arduino GPIO14 (D5)

Sensor2 echo to Arduino GPIO12 (D6)

These sensors work ok at 3.3volts. This is good as level converters are not needed.

It's probably a good idea to take the supply and ground for the sensor boards from the DC-DC converter output pins when doing the final wiring in the box but for testing use the Arduino 3v3 and GND pins.

Wire both sensors VCC to Arduino 3v3

Wire both sensors GND to Arduino GND

The LED is only on for 50mS every 2 seconds so I didn't bother with a current limiting resistor but a 1/4W 470R resistor can be added if you wish.

LED Anode (long leg) to Arduino GPIO13 (D7) Through a resistor if desired

LED Cathode to Arduino GND

Now plug the Sensors into the back of the sensor boards, they have 2 mtr long co-axial leads.

I needed to extend these, my tanks are 6 mtrs apart. I used some old co-axial cable I had laying around.

If you do this, be sure to cover all soldered joints with heatshrink.

That's all the wiring, next is the software.

Step 3: Collecting and Installing the Software

This water level monitor uses Blynk to send info from the ESP8266 board to your phone via their servers.

The Blynk server in the cloud serves up your app with the information in the widgets on the phone. When signing up with Blynk you are given 2000 energy points. These points are used to 'buy' widgets for your program.

2000 points is enough to build this water monitor app.

I actually have a 'local server' running on a Raspberry Pi, this allows unlimited points and better security. It does not use the Blynk server at all, completely independent.

Installation and setup of a local server is beyond the scope of this instructable. There are many instructions and tutorials on the net for doing this starting with the Blynk website.

The final version I coded for OTA (over the Air) updating as it is remote and I didn't want to pull it all apart just to update the software. I'll discuss the OTA software changes and methods later.

While on the bench we have the USB serial to upload code.

First thing you will need is the Arduino IDE if you don't already have it.

Get the Arduino IDE here Arduino IDE. Follow the getting started link on how to install this software, it is not part of this instructable.

Download the Blynk library here Blynk library, download link is at the bottom of the page.

Follow the instructions on that page to install the library.

Get the phone app here Blynk App.

An account can be created now for Blynk if you wish using the app. Remember the login email address you use, you'll need it later. Probably best to use your every day email account.

You will also need this library:

NewPing This is an excellent library for using ultrasound devices that does all the timing for you. No need to mess around with milliseconds etc.

These instructions below need to be done to install all the ESP8266 software.

Starting with 1.6.4, Arduino allows installation of third-party platform packages using Boards Manager. We have packages available for Windows, Mac OS, and Linux (32 and 64 bit).

Start Arduino and open File > Preferences window.

Enter ( copy and paste - without the quote marks) ```http://arduino.esp8266.com/stable/package_esp8266com_index.json``` into *Additional Board Manager URLs* field. You can add multiple URLs, separating them with commas.

Open Boards Manager from Tools > Board menu and install *esp8266* platform (and don't forget to select your 'NodeMCU 1.0 (ESP-12E Module)' board from Tools > Board menu after installation).

From the menu select Sketch > Include Library > Manage Libraries. Allow it to finish downloading. You should see the Blynk libraries installed.

For your PC to communicate with the Arduino boards the USB to Serial software (We ESP12 USB-UART CH341SER_win driver) needs to be installed. This is needed for all Arduino comms over USB. Get it here

That's all the software set up hopefully.

Step 4: Test Code for the ESP8266 Board

When I write software I like to build it up from small beginnings and continue testing as I go.Writing a long program and finding it doesn't work is difficult to debug.

So we'll start with two sensors reporting back the information to the serial monitor built into the Arduino IDE.

No reporting to the Blynk server, OTA or WiFi yet.

Double click the 'water_code_1.ino' file below, after Arduino IDE starts go to File > 'save as' and save to your sketch folder.

A folder will be created with the ino file inside.

Confirm you have the correct board selected, click the 'verify' button (very left button on the IDE). It should compile without error.

Connect your board to the USB cable, select from the IDE menu Tools > Port > COM n.

The correct com port can be found by simply unplugging the board and see which port disappears.

Click the 'Upload' button in the Arduino IDE and allow it to finish compiling and uploading.

In the IDE select Tools . Serial Monitor.

The LED should flash every 2 seconds and the monitor should be reporting distance, depth and liters for each tank every 2 seconds similar to the picture shown.

These sensors have a range of about 3 mtrs They are set at 3 mtrs in software anyway.

Test each sensor by moving it in and out from a solid object like the wall, you should see the figures change in the monitor window. As the distance increases this is simulating a lower water level so less liters will be reported and vise-versa.

If all works as expected go to the next step.

Step 5: Code With WiFi and Blynk

Now lets get connected to the Blynk server.

download and open the water_code_2.ino

In the Arduino IDE select File > 'save as' to your sketch folder.

Open the Blynk app, sign in. Create a new project, chose device = ESP8266, connection type = WiFi, set the theme you prefer. press the Create Button.

An authority token will be sent to your nominated email account. press OK. Further instructions on the app program in the next step.

go to your email and copy the authority token, paste it into your arduino program where it says 'char auth[] = "YourAuthToken"

Also enter your SSID and your password.

Now upload it to your ESP board.The serial monitor should display connection status before it displays the water levels.

In the next step we will finish the Blynk project in the app.

Step 6: Setting Up the Blynk App Program

Continuation of new project in the Blynk app....

Press the + at the top of the screen in the app, scroll down and press Value Display. Do this 4 times

Press the + at the top of the screen in the app, scroll down and press LevelV. Do this twice

Press the + at the top of the screen in the app, scroll down and press SuperChart.

Lay out the widgets like the picture. A long press on the widget gives you handles to resize them.

Color them as you see fit.

Press the first Value Display (top left), name it Depth 1, select V1, 0 to 300 and PUSH

Press the second Value Display (top right), name Depth 2, select V4, 0 to 300 and PUSH

Press the third Value Display (2 down left), name Liters 1, select V2, 0 to 9999 and PUSH

Press the forth Value Display (second down right), name Liters 2, select V5, 0 to 9999 and PUSH

Press the left Vertical Level, name it Level 1, select V3, 0 to 1600, OFF and PUSH

Press the right Vertical Level, name it Level 2, select V6, 0 to 1600, OFF and PUSH

Press the SuperChart, names Liters 1 and Liters 2.

Press the icon (data stream) next to Name, PIN = V3, slide switch = VALUES, minn = 0, max = 1600

Press the icon (data stream) next to the second name, PIN = V6, slide switch = VALUES, min = 0, max = 1600

You can play around with the other settings to suit your preferences.

To delete a widget drag it to the top right of the screen.

If everything looks ok, press the play button top right of the screen. If your Arduino is running you should see the same numbers (except distance) come up as in the serial monitor.

Step 7: Setting Up OTA Updating

OTA or 'Over The Air' uploading of code is a really a useful feature, particularly in this case where the ESP board is in a box and outside.

This is a fairly simple process:

1. a OTA bootloader is first uploaded to the board.

2. The board is reset by pressing the reset button on the board.

3. your new code for the water tank project containing the OTA additions is uploaded to your board by USB.

Future uploads are achieved by selecting the WiFi port in Tools > Port.

Go to File > Examples > ArduinoOTA > BasicOTA

The program will load up, enter your Network Name and Password in the code near the top f the program.

Upload this to your board.

Now press the reset button on the board.

Go back to your water tank program and un-comment the 3 places shown in the pictures, these are required now for OTA uploading.

Upload this to your board, use serial USB.

If you look under Tools > Port in the Arduino IDE you will notice a new port. It will have 'esp8266', the board ID and the board IP address.

For future upload use this port, no need for a USB serial connection.

The board can now be powered by some other means but OTA will still work using power from the USB cable.

Step 8: Mount the Boards Into the Box

I mounted the ESP8266, both the Ultrasonic boards and the DC-DC converter in a IP66 rated box as it would be outside and exposed to the elements. I did however put the box inside a UV safe plastic bag just to be sure. I felt the connectors could leak water into the box.

I wont go into detail about mounting the boards; your box may be different to the one I used.

I didn't have any female connectors for the Sensor boards so I soldered the wires and covered with heatshrink.

If you have female-female wire links, all the better.

Mount the DC-DC converter to a position where the power connector can be plugged in from outside.

Take all the power and ground connections to this board so we avoid ground loops. Use 3.3 volts for everything.

Drill a hole for the LED, try to make it a tight fit so no adhesive is necessary.

Check everything, especially the power wiring.

Plug in the power pack and connect to the box, plug in the sensors and switch on.

You will not see anything on the serial monitor of course as we are not using the USB serial connection, but check your phone app.

Move the sensors around, the figures should change in the app.Bear in mind a ping and info transmission is only done every 2 seconds.

Step 9: Mount the Sensors in the Tanks

Again I cant go into detail about mounting the sensors in the water tanks, your tanks are most likely different to mine.

It does however have to be within your homes WLAN WiFi envelope. If your tanks are at a greater distance, WiFi extender could be used.

However, fix the sensors pointing directly vertically downwards toward the water at the height you measured before, see the picture, should be at 'Depth1 and Depth2. It is assumed the water can never reach this depth before overflowing. You don't want the sensors drowning.

I should also point out these sensors have a minimum range distance of 20 cm, this is because the transmitter and the receiver share the same ultrasonic speaker and has speed/timing problems under that distance.

Connect everything up and ensure everything is weather proof.

Apply power, it takes a few seconds to boot, you should see the water levels on your phones Blynk app.

Any questions I will try to answer as best I can. Good luck with this useful project.

Don't forget, if you like this instructable, please vote for me in the wireless Contest. Thanks

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    65 Discussions


    2 months ago

    please note DJman230 question regarding the use of 4cm diameter pipe the water tank. is it oK?

    1 reply

    Reply 2 months ago

    try it and find out. Experiment, research R& D, that's how to see if something works.


    7 months ago

    awesome project. thank you for the clear descriptions and the example code.. I was able to add a water flow meter to this very easily.

    just have to test the real location for wifi connectivity where the box needs to go.

    4 replies

    Reply 3 months ago

    Can you post or PM me, the code for the flow meter. I also want to add one.Thank you


    Reply 3 months ago

    See instructables topic How-to-Use-Water-Flow-Sensor-Arduino-Tutorial


    Reply 7 months ago

    Thanks for the compliments.

    Good idea for flow rate meter, good luck with tests.


    Reply 7 months ago

    one suggested update.. there is a file you can include to use the 8266 D pin numbers..
    #include <pins_arduino.h>

    then change your code to use the D pin numbers..
    //** SENSOR PINS
    const int PingPin1 = D1; // GPIO5, D1
    const int EchoPin1 = D2; // GPIO4, D2
    i fell into this cause I accidentally (no knowledge) used D3, which reset the flash every time the board was powered on or reset. so I needed to change to using D5, but couldn't wrap my head around the gpio pins to external pin..


    Question 5 months ago

    Can you please help me when I do the upload it claims that newping will not work with esp8266 any help will be welcome.Of course after upload of water level1 nothing happens

    1 answer

    Answer 3 months ago

    My arduino says the same, but do not bother. Do you compile and upload with no errors.
    Try putting the sensor, looking the ground and set baud rate at 115200


    3 months ago

    Hello again. I am currently building this project and I got some questions.
    1)What happens if the minimum range distance is less than 20cm
    2)I have a square 1tone tank. So in const int Area1 I have to put 1.000.000 ?
    3) Program compiles and uploads succeful but I have no measuring from the minitor

    3 replies

    Reply 3 months ago

    Sensors must be minimum 20cm above Max fluid level.


    Reply 3 months ago

    Thank you. I have finished it.Great instructions. What do you think about my design, for fixing the sensor over the tank?


    Reply 3 months ago

    Just solved
    #3 The sensor must be very well placed above the water (or ground if you are testing). Level it perfect.
    #2 I put const int Area1 = 10000 for my 1 tone square tank and I got the results I need.
    #1 Correct me if I am wrong but, I should place the sensor 20cm above my tank maximum level?
    My tank looks like the one in the photo. I am thinking drilling the lead and gluing a 4cm diameter, plastic tube at the top, and placing the sensor on top.
    Is the 4cm diameter enough for the ultra sound beam?


    3 months ago

    Thanks for the sharing of this great project. I managed to get everything working. Just need to adjust my tank dimensions and then fit everything. One thing I'm struggling to understand. You say you have two tanks, with a combined volume of 30 000L...so are they 15 000 each? With the diameter1 = 182 and depth = 225 I get different volume of 5853.5 Liters per tank?


    5 months ago

    Hi all, I would
    like to congratulate you for the great project, I'm really looking forward to
    doing it for my house, I tried to do the procedure and I could not do the
    installation to install Blynk, if I can help, I'll be very grateful:


    Here is the path on the computer that was performed:

    C:\Program Files (x86)\Arduino\libraries

    C:\Program Files (x86)\Arduino\tools

    In the Arduino program after procedure the blynk appears in ( Tools )

    But in (Tools \ board) it does not appear




    6 months ago

    Hey! Just got my parts, but im only getting jibberish in the serial console?

    Ive done this:

    - tried different boards

    - tried a different computer

    - tried both sketches, nr2 acctually connected to my wifi for a second.

    - Baud is set to 115200

    - both sensor lights light up and blink in sync with the board led. It then writes the jibberish.

    Would you have the time to help out? What am i missing

    4 replies

    Reply 6 months ago

    Check the serial console bottom right corner buad rate is set 115200


    Reply 6 months ago

    Thanks for the super quick reply :)

    Yes i have made sure the baud is 115200 in the dropdown..



    CP2102 chip version was ordered.

    I see a big how-to in the product description, flashing the chips.. Is that nessesary? There it mentions 9600 baud several times. Could it be the chip needs configuration? Answer: no.

    Edit 2:

    Rebuilding everything from start.

    Now im on the right track i believe. Will update later.

    PS WARNING: library NewPing claims to run on (avr, arm), is nothing to worry about yes?


    Reply 6 months ago

    First off, does your code compile? Use the left button in the IDE.
    Check all the wiring, what there is of it. If it compiles OK, upload it to the board, which you should have selected under the 'tools-boards'menu.
    If it doesn't compile check where the error is, it will be highlighted.
    Let me know what happens.


    Reply 6 months ago

    Hi, thanks again.

    Everything is working great, not sure what the glitch was.

    I am going to consentrate next on getting the data sent to my lan blynk server i set up, i dont need the fancy graphs. only a .csv dump for instance. Perhaps i could use the serial print`s to store a file!