Picture of Water Level Indicator with Alarm
Today I am going to talk about a very useful project that I had taken up. It is called the Water Level Indicator. Nowadays everybody has overhead tank at their homes. But everyone who has a water tank above knows the kind of problems that they face. Firstly there is no system to track the water in the tank. Then there come a secondary problem that is when their water pump is started they have no idea when it gets filled up and sometimes there are situation where the pump keeps on pumping water to the tank and the water starts spilling out from the tank. There is wastage of energy as well as wastage of water.

Later History
This project that i had taken up is the result of  long hours of research of work at the Internet as well as long hours of thinking. I had made various versions of the projects earlier but at last i came up with this final product. I bet this has been tested and i can now firmly say that the model would work flawlessly without any complains for years. I am saying this as i have installed this models to various houses in my neighborhood and all are working fine without any maintenance. And indeed this model is admired by all who uses it.

The Situation 
The house where I live in has an overhead tank which is about 30 feet from the ground level. I was getting bored going up the rooftop to check whether the tank has filled or the water level was below to start the pump. I had to do this again and again. Then I sought for a solution. I always used to think of the possibilities of how can this problem be tackled in an electronic way. After years of research and by trial and error,  I found one and wanted to put whatever I have done out here so that it may be helpful to someone who has a overhead water tank at their homes.

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Step 1: The Working Principle

Picture of The Working Principle
Basically the unit is made up of various sensors acting as a switch. Let me explain in a simple way. What happens is when you turn on you water pump, the water starts to get pumped from your underground reservoir  or from your underground water supply from the pipes to your water tank. In the tank there is a set of sensors ( to be precise there are 7 sensors), in the water tank. Just think them as a switch, as the work of the sensor will be to connect a circuit. I will explain in details in my instructables. So the water starts to get filled in the tank and when the water level in the tank starts to rise up, what happens is that the sensors that is installed in the tank starts to get activated one by one indicating the water level in the tank. And finally when it reaches to its top most sensor, there will be a visual display as well as a sound from the unit indicating that the water has filled in the tank and one can be alerted that the tank has been filled up and the water pump has to be switched off saving the electricity bill as well as over flow of water from the tank.

There are Four parts in this project:-

(i) The Sensor Part

It is generally a fixed support inside the tank having some nuts and bolt with wires coming out.
(ii) The Circuit Part
It comprises the brain of the module, where in all the various inputs from the sensors are fed. It is the unit from where you will get all the information of how much of water is in the tank.
(iii) The Power Supply 
It is the part where in you will be converting the A/C voltage to a regulated voltage of 5V to the Circuit.
(IV) The Buzzer Part
It is responsible for bringing up the sound when the water level fills up in the tank. It will also be having a speaker or a buzzer to alert.

Step 2: The Circuit

It has numerous transistors acting as a switch and the switch gets activated when the sensors tell them to. 

The heart of the circuit is the transistors BC 547. There are total 7 transistors in the circuit and each one will be sensing the level of water present in the overhead water tank. There is one extra power LED without a transistor and that is because this Red LED will be telling us two things. Firstly when you power the unit it will be monitoring the power present in the unit and secondly it is also the indicator telling you that there is no water at all present in the tank. As because the water level is below the No. 1 (as shown in the circuit) sensor, no LED's will be lighting up, but only for the one Red LED. Therefore when you switch on your unit if you see only one Red LED lighting up then you know that the is no water present in the tank and therefore you should make you water pump on.
Then as shown in the figure i have given all the LED's in various color. Starting from the beginning is 
  1. Red LED (Indicating no water in the tank as none of the sensors are getting contact with the water)
  2. Red LED ( Level 1, indication very low water in the tank )
  3. Yellow LED (Level 2, indication of low water)
  4. Yellow LED (Level 3, indication of 1/4 of water in the tank)
  5. Green LED (Level 4, indication of half of water in the tank)
  6. Green LED (Level 5, indication of more than half of water)
  7. Green LED (Level 6, indication of nearing filling up the tank)
  8. Blue LED (Level 7, Full indication of tank and buzzer comes on)
Now as the water starts to rise up the sensors starts to get in contact with the water and the transistors are activated and there is a flow of current in the transistors making the LED's light up. Here in between the transistor and the LED there is a current limiting resistor 470 ohms, the job of the resistor is to checks that the LED does not get over voltage and destroy the LED. The transistor is biased by a 470K resistor with the ground and the sensing part is taken from the collector with a 33 ohms resistor going directly to the tank. As i have shown in the diagram the signals are drawn in the Green color. There by you can follow the LED's as they light up from Red to Yellow and then Green and finally to Blue making a sound.  

The Buzzer Part
Here you can add any of the normal buzzers that are readily available in the market and if  it is not then you can make yourself with a simple 555 IC. I am giving a small circuit diagram, it is really simple to make and there are minimum parts. It is a simple audio oscillator. I have also provide a circuit diagram here but if you are able to manage a buzzer then no need to assemble this circuit.

The Power Supply
This section contains a transformer converting the mains voltage 220V bring down to 9V. There is a bridge rectifier containing 4 diodes and making the Alternating current to Direct Current. After the filtering the voltage is then directly fed to the voltage regulator (7805) with a filtering capacitor. From the regulator IC the output voltage is then again filtered with a capacitor and is fed to the circuit. This comprises the power supply of the device.

This completes the electronic part of the project and now i will be going to the sensor part, which is also made easily.

Step 3: Putting the circuit in a box

Now time to put the compiled circuit in a small box. Here i chose a Junction box that are used in electrical wiring. It was a perfect box for this project. 
Now the tricky part is making holes in the plastic junction box so that LED can easily slip through the holes, also the spacing between the LED's should be proportionate. First take the box and draw the outline in the face of the box. First for the switch you should make a marking at the bottom right hand side. Then mark the points for the LED's. As told earlier it should be proportionate. Now unbend a paper clip and heat it with a soldering iron and make holes to the marked points as shown in the figure. 

Then cut the plastic board for the power switch. After the cut is made file at the edges so that the cut is smooth and the switch can easily fit to into the cut. Fit in the Power Switch. 

Time for adding the LED's to the panel. Let's start by adding the Red LED from the bottom end. Then to the Yellow and Green and finally Blue. This LED's should be then be soldered to the PCB as shown in the circuit diagram. For me what i did was soldered directly to the PCB below the front panel, as it gave a solid base for the LED's. 

Now fix the buzzer just beside the PCB and give the connection from the circuit board. Then also fix the Power supply at the box with the help of nuts holding the transformer firmly to the box.

For making a junction of the sensors you can use a cable connector, i used from a used TV circuit board as shown. This connector was actually connecting some wires with the television PCB to the CRT(Cathod Ray Tube of the TV), therefore i decided to use this as it had many pins. I then cut it from the PCB and numbered it from 1 going up till 8. You will notice that there were two pins extra, so i made this two pins connect together and made a common point for the sensor going to the tank. The rest of the pins starting from Pin 1 going up till 7 will be for the sensing part which will also be connected to the sensors of the water tank. 

The Nos. that i have assigned for the sensors are as follows:-

1: (Level 1) water is considerably low and pump needs to be started
2: (Level 2) water is low
3: (Level 3) Water level is 1/
4: (Level 4) Water level is Half
5: Level 5) Water level is more than half
6: (Level 6) Water level is about to fill up
7: (Level 7) Water level has filled up and alarm starts to sound
8: Common Positive Pin 

Therefore there are in total 8 supply line that has to be taken out from the main circuit board to the sensor. After trial and error, and a few failed experiments i found out that the best wire to be used in the project would be a Cat5 cable as it has also in total 4 pairs of wires and this can be blended in this project nicely. As it would be virtually impossible to buy lots of wire and then take it to the tank. It would be messy and there would be all short of wiring problem.
And one advantage in adding a  junction, while installation is that there won't be any problem for soldering the wires to the circuit while installation. It would be just plug and play. Therefore after the wire is connected to the connector. I hot glued it as it would keep the wires firmly fixed to the female connector,and there won't be any dis-connection.

My rented house that i live is about 3 stories high and i needed approximately 15 meters of CAT5 Cable. 

That end's this part of connecting the cable with the circuit and the next part will be learning to make the sensors for the water tank.

Step 4: The Sensor Part

This is the easiest part of the project to build. You only have to make two conductors so that when it is in contact with water it will act as a switch, as water is a good conductor of electricity.

Lets start with finding a plastic PVC pipe or you may use any short of plastic wire casing. In my part what i did was make it with wire casing, that are utilized while wiring at houses, but if in case you don't have you can make it with a PVC pipe.
Then your next step is to measure the height of the tank that is from bottom till the neck and accordingly cut the PVC wire casing. Then mark points 1 to 7 leaving some spaces as desired. For example you can measure the whole length and divide it by seven, as because you have to mark seven different points for sensing seven different water level.

Your tank height from bottom to top is 6 Foot (182.88 centimeter),
You divide 182.88 centimeter by seven 7 then you get 
182.88 / 7 = 26.12 cm
Therefore you have to mark points at intervals of 26.12 cm

After marking the different water level in the PVC wire casing, find some 3 inch nut bolts as shown in figure. Drill the holes to the points marked keeping the size of the diameter of the nuts, It should snugly fit to the wire casing. Then as when the nut is fitted to the casing, don't bolt the nut as such. Make a wire loop as shown and then solder it's outside part so that it can slip to the nut easily. 
The length of the wire should be kept long (i.e more than 6 foot for the first sensor) and the length of the second sensor would be short then the first sensor, so this should be continued till you have 7 wires with 7 loops with varying lengths.

Now put the loops of wire to the nuts that you have snuggled to the plastic wire biting and make the wires come out from every nut that you have built. After all the wires are fixed to the nut, you should now add a common line to the wire casing. For the common line you can use a naked wire running through the nut bolts bare touching each other. The gap of the naked wire and the bolt should be kept minimum and if you want you can solder a small piece of wire to the common line just beside the nut and bolt as the sensing would be more. when the water comes in contact with the common wire and the bolt, there will be transfer of current from the naked wire to the bolt and the sensing is done.

After connecting all the wires to the bolt there will be a mess of wire hanging from the wire casing, what i did was hot glued all the wires in a line wise fashion so that the wires don't fall out of place. All the wires were then junctioned to a PCB board from which the sensing part would be taken out. This is shown in the figure. Therefore this completes our sensor also.

Now for the final part where i will be talking about the Installation.

Step 5: Installing the Device

The final part is installing the device to the tank and make it working. 

First start with installing the water sensor in the overhead tank. As in figure this is the tank that we are going to install the sensor. Just survey the tank from every side to see that you can fit the sensing part. Now take the sensor rod that you have prepared and dip into the tank so that it just touches the bottom. Now fix the sensor into the water tank by screwing a screw directly to the water tank so that the water sensor rod doesn't move. The sensor rod should not move. That finishes the part of installing the sensor rod to the water tank. Now to the device that we are going to install.

Now for installation of the device you should find a suitable place for easy view of the LED lights. It should also be installed in such a way that it should be out of reach of the children. The best place for installing the device would be in the kitchen of a house. This is because while working in a kitchen you may want to turn on the water pump and just cooking you would be able to get the updates from the tank on how much the water has filled. Just drill two holes in the walls and install it using a L hook. Screw the two L hooks to the device and fix it to the wall. It should be firmly fixed. Then take the A/C 220V feed from any socket and give the power to the board. 

Thus finishes the installation of the device and test it by turning the device on and checking the water level in the tank. For testing just put the power on and you will see some of the LED's glowing, indicating the level of the tank, if you see only one of the RED glowing then your tank is fully empty and it is time you should turn on your water pump. After the pump is on you will then see after some period of time that the LED's will start to glow from bottom up till the final Blue LED will light up and sound up the alarm.

And now we have successfully installed WATER LEVEL INDICATOR.
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junotomo2 days ago

the power supply is 9v or 5v ?

i have made it but my family is afraid of installing it they are afraid if it will very dangerous to work with taps when this circuit is in on condition

NiravB15 days ago
Hi i made this ckt it work s perfect but when tank is full buZzer is not ring loudly.

When i short comon wire n last led wire it rings loudly.

Any one can help me to solve my problem.

Thanks in advance.

i also want to design pcbs so i will be very thankful if anyone can tellme all the requirements for designing and printing of pcbs at home

i want to know any good microcontroller programmer hardware and software as i want to learn to program and burn almost every kind of microcontroller so can anyone please tell me name of a goof microcontroller programmer device that supports almost every microcontroller...

can i use 400k ohm and 47 ohm resistors

Hi can any one tell me how to get rid of electrolysis problem which break wires in water tank

ShiladityaD1 month ago
hei i just connected the relay directly to the last output, i have given the relay a 12 v supply directly, and the neutral is via the master ckt, relay seems to work, can i connect it to motor???
ShiladityaD1 month ago
Hei thanks for this simple circuit, i just made it, I just want to know if i can drive a relay to stop the motor. My logic is , 'take the output of the last level give it to a driver IC like L293D, get a 12v output frm IC andr drive the relay, its a 1/2 h.p 240v motor, I wanto connect it directly between phase lines, like a switch' is there any flaw??? help me out
seethasub2 years ago
There is mistake in showing collector and emitter of the transistors. Collector should go to positive hence LEDs cathode should be connected to collector of BC547 and emitter should go to common negative line.
raikut (author)  seethasub2 years ago
This issue has been discussed earlier, please go through the comment section and watch the given video

RenjithC raikut1 month ago
Transister will work though biased collector emitter inversely . Collector is lightly doped in order to have high voltage withstand capability. However, one major advantage of operating the npn transistor with its emitter and collector roles reversed is that the saturation voltage drop across collector and emitter is lower than that obtained in the normal mode, inspite of having lower current gain. This is why such devices were used as analog switches in low voltage control electronics in discrete applications. So no problem we can go head with this collector emitter inverse connection as this circute is operated by low voltage. No much power gain . So there wont be much heat to dissipate . I think for buzzer it is better to connect load in the collector line .
information courtesy :-Sujit K. Biswas · Jadavpur University.
SujalY2 months ago

Can anyone help me with the terminals of BC547. I am a bit confused :/.

Use aluminum foil (2 pcs) glued to a plastic backing as an electrode plate. will weather far longer than just wires.

SaadiM3 months ago

hey guys could someone explaine the circuit analysis

kcrajiv3 months ago

I have doubt whether this will have electric leakage in water tank leading to shockage. Kindly clear my doubt

onlynb1 year ago

thanks raikut for this project.. ive made every exactly you have written but the sensors in overhead tank gets corroded in just two weeks . after that the buzzer sound gets low and some LED's start flickering. pls telll m some solution on this.

sbiswal onlynb1 year ago
Hm I also have same issue , what I do is cleanup wires every month :(
AdithyaN1 sbiswal8 months ago


Have you tried anti-corrosive(AC) materials like AC paint or AC powder which are available in market. I am also planning to make one for my home.

This can cured by using a float that is sealed and designed to be in water. It acts as a switch. I have two 2500 gallon water tanks with 5 floats attached to it. No problems and works flawlessly. Electronics submerged in water will only last for so long due to electrolysis, the same phenomenon on outboard motors which is why they have zinc plate that is softer than the metal for the motor. So it eats away slowly at that instead. Email if you want help.

onlynb JasonS114 months ago

can you pls send pic of tht switch?? or its web link.

Nice one. However, one problem with such circuits is the corrosion of electrodes due to the high current. I've been using this water level indicator circuit for several years and hardly needs cleaning. Maybe its the low current needed to trigger the CMOS IC switch.

Which diode will i use as the full wave. Rectifier
Which diode will i use as the full wave. Rectifier

can some one let me know the parts used

Alirazzaque85 months ago

Hello Mr.Raikut i have chosen your project and i want to have some modifications in it. I want to have a motor controlled circuit so that when the level reaches to the last point the motor switches off by itself. Can you help me with that ???? Waiting for your suggestions in this regard

Tutancof5 months ago

If am not wrong your buzzer circuit need additional connection for 555IC pin 4 and 8.

sim amosl6 months ago

hey can i use BC 548 instead of 547?

Tutancof6 months ago

Can i use any kind of 555 ic NE, NA, SA, SE????

denisserhein6 months ago

hi raikut! tnx for the project,..just have few suggestion to make this project more useful,..how about instead of alarm,we make this like start stop motor circuit,..you know,if it reach the water level required,the automatically switch off the motor,..and if it is at low level it automatically switch on,..do u think it will work,..pls help me try this,..

also sorry for my "english",..

There are many ways to do this. A pump is a high draw AC appliance, but with the proper care and design can be accomplished. I use solid state relays a lot with low control voltage. Meaning only a few DC volts can activate an AC replay that can handle 50+amps. Depends on what you are looking to do exactly.

kk raikut take your time but plzz raikut try to make that fast because i had to make this project before 5th of dec ..i have a exibition so i have submit this..and once again thank u very much for giving me your precious time....
Hi I am really impressed by your home made water level indicator with alarm. I am only worried about electricity leakage if by any chance .Also whether you will make one for me as I will pay for the cost and labour involved. I am requesting you because I have little knowledge of the circuit and assembling the required components. Moreover I am a senior citizen and am not able to assemble the devise. Kindly reply . Thanks.
I would like to help you Mr.Sharma. Please do mail me your details to genn.sathish@gmail.com
raikut (author)   A K Sharma8 months ago
I would be really very grateful if only i could have helped. If i would have been there in India, i would have definately made one for you, but now i am abroad in Dubai as i am working here.
I would have also been pleased to make you one for yourself. But here in Dubai m always busy with work and moreover its hard to get spares here. Anyways thanks for your interest in my Project.
raikut (author)  aditya swaroop2 years ago
Well I am very Sorry! The Circuit Diagram that i had given was wrong. Now i have rectified the schematics and now you can check it and wire it again. Actually the Sensor wire would go to the base and the Collector would get the negative Voltage. 

Please check the diagram above and you can see the transistor testing video and the picture here that i have posted
Dear Mr.Raikut,

I'm sathish kumar working in an Industrial Automation company which deals in automating factories and process industries. My designation is technical Sales Associate. I do know the way to handle plc, drives, scada etc. Will i get an oppurtunity to work in overseas
depauw9 months ago


This seems te be exactly what i need, but for me it has to work the other way around.

I like to ge signal when the water in my tank is running low, and not when it reaches a high level. Is this possible?

Note that I'm not a genius in electricity, I'm a Pharmacist :-)

Kind regards

Ya it is possible sir/madam. i would like to help u. Can u push me a mail about your details through genn.sathish@gmail.com
denisserhein6 months ago

hi raikut! tnx for the project,..just have few suggestion to make this project more useful,..how about instead of alarm,we make this like start stop motor circuit,..you know,if it reach the water level required,the automatically switch off the motor,..and if it is at low level it automatically switch on,..do u think it will work,..pls help me try this,..

also sorry for my "english",..

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