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.

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Step 1: Things you need...

Picture of things you need...
4 - bc548

6 - 220 ohm resistors

3 - colour led

1 - buzzer

1 - 9v battery + battery clip

Step 2: Circuit diagram

Picture of Circuit diagram
The circuit consisting of 5 sensing probes which is dipped in water to sense the level of water. The probe A is connected as common to other four , which should be at the bottom most part of the water tank, also it act as a reference level. The probes B, C, D and E are set as minimum, minimum+ , middle and maximum level respectively.

Assemble the circuit...... 

Step 3: FINISH.. :)

Picture of FINISH..  :)
When water in the tank touches the probe A and B both, a small current flows from A to B through water and to the base of transistor T1 via a 220KΩ resistor. As a result the transistor conducts causing the LED1 to glow. Similarly, when water touches sensor C, LED2 glow and indicates that WATER is at minimum+ and when water touches sensor D , LED 3  glow and indicates that WATER is at. MIDDLE . Finally, when the water touches sensor E ,  BUZZER turns on and indicates the tank is completely filled.

Biscuitus1 year ago

This is exactly the circuit I was looking for but battery wouldn't work for me as it's in a machine shop and we have too much going on to keep track of it and I don't feel like making a low voltage circuit, but I do have a 5v 1A wall wart, and all my math says I can do it, albeit my LED's may be dim...thoughts?

Also, very nice instructable, but maybe you could put the specs of some of the things you used (i.e. wattage of resistors, speaker specs etc.)? I know that for this circuit you could easily use a 1/8w resistor but the speaker I just kind of hummed a few bars and faked it and used a 1.5v speaker and put an LED in front of it to step the voltage down a touch.

Er Varun Goyal (author)  Biscuitus1 year ago

use a battery adapter in the place of a battery , soo that it reduce the cost and save your time also .

I'm going to use a voltage divider and knock it down some. I lose a little in heat but it's for a Wire EDM water tank that I'm constantly over filling (and that wreaks havoc with the accuracy) so it'll get some cooling. Thanks for the response!
Er Varun Goyal (author)  Biscuitus1 year ago

thankyou sir , for your positive feedback .

maybe you can by modify the above circuit accourding to your requirement . :)

zsoltinyo1 year ago

Does this work with motor oil?

If it works with motor oil you have much bigger problems than oil level :)

Er Varun Goyal (author)  zsoltinyo1 year ago

no sir , Engine oil does not conduct electricity
because there are no charge carriers in it.

This can prove useful in my boat. Thank you much for posting
Er Varun Goyal (author)  highwind0011 year ago
anytime buddy.. :) and thankyou
SrinivasV122 days ago
SadafS3 months ago


SadafS3 months ago


aqsas4 months ago

sir i wants to know that when tank overflows & circuitt is in on position and at the same time when someone uses tap water below, then is there chances of shock

ahmadbidai5 months ago


I'm working on a similar project of this type, but in my own case, i'm using a microcontroller and it's failed me at different trials. Perhaps i'm getting the connections wrong or something. I'd appreciate if you could help with the procedures.

Thank you!

sohailkhan2465 months ago

My water tank is at 2nd floor, will the circuit work at ground floor

sfranch made it!6 months ago

Thanks Boss!!

depauw8 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

mahesh.pagda9 months ago

why we can use inwater level indctior in use 220 ohms rasitance? we also use 260 ya 200 ohms rasitance

mahesh.pagda9 months ago

why we can use inwater level indctior in use 220 ohms rasitance? we also use 260 ya 200 ohms rasitance

Shariffs10 months ago

Can i connect the Relay to the o/p of the low and high indication level, so that i can control the motor also. need suggestion please.

where we have to connect the terminals of buzzer??

Er Varun Goyal (author)  veerkumar.rathore10 months ago

connect the buzzer on the wire highlited in the pic (PFA ) in series. please check the positive and negative wires. you have to connect the postive wire with the positive terminal wire of the battery and the negative one with the negative terminal wire of the battery .

inst. cmmnt.JPG
sylvain0110 months ago

thank you it's good for my sump pump and my hot-water tank

if my English is not good its

Er Varun Goyal (author)  sylvain0110 months ago

any time sir :)

DWjemar12310 months ago

wattage of the resistor?

swamy20110 months ago

and also by using with relay and motor, the motor is automatically start when the tank is empty and stop when the tank is fully....if you know this is one please explain...........

swamy20110 months ago

also by using motor and relays the motor is automatically start when the water is empty and stop when the water is full....if you know this is one please explain..because this project im using as a mini project

swamy20111 months ago

is this ckt working correct or not

Er Varun Goyal (author)  swamy20111 months ago

yes, the circuit above is working fine and is tested by me... please watch videos in the manual above or

click here to watch on youtube..

p mishra1 year ago
hey did u saw a vid of learn by watch and made it
Er Varun Goyal (author)  p mishra1 year ago

Yes, but maybe the circuit there is not correct.
In that circuit -ve pin of L.E.D. is connected to the +Ve pin of the battery and the circuit was not working correctly. So I Modify the circuit and made it better.
now it works fine...

compare both the circuits and find the difference , try to make both the circuit to find the better result of difference :)

In what configuration is the BJT used?? Can u please tell me a bit about how did u design this circuit?

Thanks a ton.

sir , the circuit is based on 4 transistor switches. Each transistor is switched on to drive the corresponding LED/buzzer , when its base is supplied with current through the water through the electrode probes. :)

Well, I got that. Your circuit works fantastic and is very simple. I am asking whether the BJTs are working in Active region or Reverse Active region? Because generally the collector is connected to positive terminal of battery.

samalert1 year ago
I was really expecting a video of project in action.
Er Varun Goyal (author)  samalert1 year ago

dude.. here is the video of project in action.

thankyou for your feedback :)

Dude i really wanted to hear the sound the buzzer produce. Cause i was thinking of implementing it in my house for some reasons. Thanks a ton for posting the video.

Er Varun Goyal (author)  samalert1 year ago

anytime bro. .. and thanx to you too .
Er Varun Goyal (author)  samalert1 year ago
sorry frnd...
next time jb bhi bnaunga ... video post krunga .

btw project ki pic se b pta lga rha h k iski working kya h....
Er Varun Goyal (author) 1 year ago

updated.. with video of project in action. :)