Water level alarm circuit


Here is a simple water level alarm circuit using 555 timer that will produce an audible alarm when the water level reaches  a preset level.The circuit can be powered of a  3V battery and is very handy to use.

The circuit is based on an astable multivibrator wired around IC1 (NE 555).The operating frequency of the astable multivibrator here will depend on capacitor C1, resistances R1,R2 and the resistance across the probes A&B.When there is no water up to the probes,they will be open and so the multivibrator will not produce oscillations and the buzzer will not beep.When there is water up to the level of probes,some current will pass through the water,the circuit will be closed to some extend,and the IC will start producing oscillations in a frequency  proportional to the value of C1,R1,R2 and the resistance of water across the probes.The buzzer will beep to indicate the presence of water up to the level of the sensing probes.

Circuit diagram with Parts list.



  • The circuit can be powered of a 3V battery.
  • Assemble the circuit on a good quality PCB or common board.
  • The probes can be made of two insulated copper Aluminiun wires.
  • Place the probes at the position where you have to sense the level.
Note:- We have recently developed a fully functional Water Level Controller using Microcontroller. This water level controller monitors the level of the over head tank  and automatically switches on the water pump when ever the level goes below a preset limit. You may see the circuit, if you are interested.
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117 thoughts on “Water level alarm circuit

  1. David Kasai

    Hello and thank you for this. I didn’t have a 2.2uF cap so I used a 1uF cap. I also tried using a 5v boost for the 3.7v battery and it seems to work nicely. More sensitive. I also used a double stranded 28 gauge wire for the probe/sensor by trimming a tiny bit of the wire jacket at the end so it works like a double contact sensor with water closing the circuit.

  2. Marilyn

    Hi, I need a circuit which sets an alarm when the probes are not in water. i.e the level of water is low. Is there a way how this circuit can be reversed please ?

  3. Shozab Ali

    This circuit works perfectly.
    I replaced buzzer with LED, the LED blinks when prob A & B are short circuited.

  4. karan

    The circuit diagram shows that it is operating on a 3v battery. But i checked the datasheet of NE555. Its operating voltage range is from 4.5-18v. Will this circuit work on 3v voltage source?

  5. umaprashanth

    Its can be easily done on the bread board. Anyone let me know the procedure of working And I don’t no wat and how to work with pcb . Plz give me the complete details about pcb

    • seetharaman

      It can be assembled on a standard IC PCB available in PCB shops. The operation of this circuit is, a standard timer IC NE555 with Piezo beeper. once the water level touches the probe the timer will start oscillating and beeper will beep. Once water level goes bellow it will stop.
      view this site for the PCB type

  6. chandru

    I m new to projects
    … Tell me briefly about this ckt… Can buzzer be replaced with LED? Reply me..

    • CHOGC

      Really thanks for making the correction. I’m breaking my head with the output. You gave the right answer and helped me a lot.

  7. ushodaya

    yes this project works.. i made a mini project y collecting this information.
    this project is so simple that i made it in 15min.with good result..!
    after connecting all the equipments as per the circuit diagram.,then finally a two wires are connected to the buzzer.And I kept that in water glass. and started pouring water when the water reached wires(connected to probes),the buzzer started sound.
    FINALLY… Water level alarm circuit started working.. I succesfully completed my mini project.

  8. anupam kumar singh

    sir, i want to know that how much cost will be to make this experiment…and suggest me more easy projects which i can perform easily. and respective prices also….mind it sir that i m a b.tech 1st year student… ok bye sir .. good bye… reply must sir… i m waiting for your suggestion….for this i shall be highly greatful to you..
    one thing more sir..
    i m very weak in progromming languages ,,, such as C C++ .. oops etc..
    please tell me the importance of programming and could i be a good engineer without commanding in this subject,,,,okk see u soon sir byree…ebye

  9. krish

    hi frnds.. i wud lyk to do ths project. but im new to projects..so plz help me out. is pcb necessary to connect the ckts n frm wer do i get all the required components in bng? is sp road rite place?

  10. Shruthi

    Hi, i’m very new to do projects, this 1’l b first. So can u plz send me the whole things required to complet this project lik pcb design, software if necessary, any precautions to take, plz plz

    • guhan

      for simple ckt design there is no need of software. implement this circuit in breadboard then implement in the printed circuit board(pcb). circuit design is easy when you learn so learn as much as you can,
      have a good day

  11. Carlos

    Hi… Need some help here, please… Is it possible for this circuit to work “in reverse”?… Meaning, I need the buzzer to sound ONLY when both probes are NOT in contact with water… Like a low water level alarm, with both probes posicioned in the BOTTOM of the tank… If possible, what changes have to be done in this circuit?… Thanks!

  12. Goitom haile

    Just now i purchased every thing. I am new to electronics, don’t have any background in electronics, just for hobbies i am doing this project, plz help i am cofused regarding the IC 555 terminal, in diagram it showing 1,2,3,4,5,6,7,8 how to locate the nos in IC plz help and one more thing can solder resister in any direction regards.

    • Seetharaman

      Please go through the datasheet of NE555. From the top (from the component side)it will be anticlockwise from the dot or the index shown as pin number 1 and count anti clockwise. (from the soldering side it will be clockwise)

  13. narendar

    instead of 1kilo ohm&100 kilo ohm resistors we use another resistors what will happens.
    capacitor 2.2 uf replaced by 10uf what will happen

  14. normal

    hello sir you have used here this ic as astable mode hence the buzzer can beep until the probes in contact with water am I right?

  15. jeevi

    i,m going to do this as my project.pls send me a mail abt the whole process
    and can u convert the 1k &100k resistance to ohm .or do we get in k in shops.and where do we get the components,

  16. Sruthi

    I haven’t executed this circuit but i have a doubt. when the supply is given to the circuit won’t the buzzer work immediately giving out the noise signal? how should i avoid this problem?

    • Seetharaman

      hi sruthi ic pin 3 will be high. once a and b are linked by water it will go high and low as per r1, r2 and c1. hence the electronic sounder will bleep whenever pin no 3 goes low.

      • priya

        i done this project but the problem is that even the probes are not upto the water level the buzzer will ring…means as soon as i give the supply the buzzer will ring . pls help me

        • Kedar Vaze

          the crkt diagram sketched above is wrong.don’t give supply to buzzer but to jst pin no.8&4,which are shorted ground capacitor c1 so it will produce frequency above 60Hzs which is necessary for buzzering

          • Zashu

            @Kedar_Vaze PLZZZ give me some more imfo abt this problem …. means… tell mee where i can connect the buzzer then ..and from where to where i should give the power supply to the circuit… .. m confused if we dont give the power supply to the buzzer..then where will b the positive terminal of the buzzer b connected ..tell me the solution pleasee.. 🙁

  17. Divya sree.K.R

    i need a brife information about “Water level alarm” .Its introduction,circuit diagram,procedure,function,merits & de-merits and its conclusion…Plz reply
    me as soon as possible,plz plz plz……….

  18. Harsh Patel

    Why you are using 555 timer?
    Can simple circuit is use (1 resistor,capacitor,battery,buzzer)?
    Is the various type of buzzer is sell? & according to which type?

    please tell & guide me

  19. sumona

    i have used 5V power supply.. the circuit works.. have tested it using led in place of buzzer.. but d buzzer is not producing any sound.. can u please help;.. whats is wrong with d buzzer and how to make it work?

    • Zashu

      According to the above circuit…i have a problem… the probes are not connected but still the buzzer is producing sound.. infact the circuit is correct according to the given diagrame.. plzz tell me wat should i do to make it correct .. !! need a solution ASAP.. !!
      From the above comments i saw that…the circuit is nt correct..one of them says.. tht i should nt connect the buzzer to the power supply…but the confusion is that then from where to where ill connect the buzzer and the battery.. !! .. .Plzzz help me out.. 🙁

  20. Saptarshi Das

    Is there may be any problem if I use above circuit with 9volt battery if so what are the changes required? I have already implemented this circuit for my home over head water tank. It is working fine but the loudness of the buzzer is poor as the water tank and the circuit having distance almost 60 feet. Also I would not like to change the battery frequently what is the solution for that.


  21. mounika

    i need complete details regarding this i need how to make water level indicator.it`s very helpful for students.plllllllllllllz do that

  22. shruti

    when the supply is given,the buzzer starts beeping.even when the probes arent in the water.!!!can u please give the solution for this.i also needed the design for this circuit.so can u please mail it to me?

    • Zashu

      The same problem goes with mee too… the probes are not connected but still the buzzer is producing sound.. infact the circuit is correct according to the given diagrame.. plzz tell me wat should i do to make it correct .. !! need a solution ASAP.. !!

  23. kaushik

    I want the detailed explantn abt this and i liked it and i need it urgently!!!!!plz do it as soon as possible

  24. mridul

    this ckt is fail in working coz when v give supply d buzzer starts buzzing with out touching d probes in water
    aby solution plz tell me

  25. bear

    with c1=2.2uF , R1=1k and R2=100k as shown in the circuit the buzzer does not and cannot work ! c1 must be 2,2 or 22 nF. I wonder why no one realized this….

  26. Sridevi

    hi!This circuit will work only when the water level is upto the probes rite..can we modify ths circuit by making it beep both the times when the water is at 1/4th level and when it is full.So that it will be easy for me to on and off the switch.plz reply ..

  27. jahz

    this project works!guys need some help what buzzer should i use?i tried to conect it to an alarm clk coz i dont have any buzzer but the prob is the alarm clk keeps on sounding even theres no contact in the probes.

  28. Deepesh Shah

    In this circuit where pin no.5 is not shown. So to run the circuit where it should be connected.

  29. Kamaljit Singh

    Hi Seetharaman, yr Idea has been of great help for 15 days.
    Now the ends of the wire that I dipped in the Water tank have
    sulphated and do not conduct. After every 20-25 days I need to
    clean the ends of the wire in the water tank. Pls suggest some other sensors which need no cleaning.

  30. Bijay

    Thanks to seetharaman, the project is completed i have connect the 3-24v buzzer its not working, then to test the alarm i connect a 3v bulb in place of buzzer. i notice that the light is flashing ( is it ok flashing of bulb). can u suggest what kind of buzzer should i purchase,

  31. Seetharaman

    Hi Bijay you cxan use resistance in any direction as they have no polarity like diodes and electrolytic capacitors. regarding NE555 pin connection refer following document in the out line it is shown clearly in the numbers will increase in anticlockwise direction as you view from the IC identity – screen printed / engraved side.

  32. Bijay

    Seetharaman thanks for the help.
    just now i purchased everything,, i m new to electronics, don’t have any background in electronics, just for hobbies im doing this project,
    pl help i m confused regarding the IC555 terminal, in diagrams it showing….8 how to locate the nos in IC
    pl help. and 1 more thing can solder resister in any direction,

  33. Seetharaman

    Hi Bijay normal mobile chargers voltage lies between 5 to 7 volt can be directly used as the IC can operate up to 15 volts.

  34. Bijay Singh

    hi all. instead of 3v batteries, i would like use transformer of 3volts. pl let me know how to built that 3volt AC-to DC, can i use mobile phone charger for that..

  35. Seetharaman

    Hi Neenoo it is 3volt DC. you can use a single lithium battery 123 or 2nos 1.5 volt cells in series. i think ac batteries are yet to be invented.

  36. Edwin Raj

    it helped our student to get some ideas for the science exhibition that is taking place in our school…. thanks a lot…. please mail me/…

  37. pawan

    sir i need a simple circuit daigram for my science project please help me within 15 aug please reply on my mail immidiately anyone please

  38. seetharaman

    Hi Patrick you can use 5amp house wiring wire 2 runs(1/18wire). You can use 5 volt power pack, which is standard these days for charging mobile phones.

  39. patrick vaz

    The tank at my place is located at 60ft above. I live at ground level.I want to connect 2 copper wires from ground to tank. but can 3 volts battery be replaced with electrical power circuit. Thanks

  40. Narendra

    if you are not able to hear the buzzer sound, then put only the sensors in the tank and connect it with rest of the circuit via the pipes which bring water to your home ,if they are made up of metal.

  41. ravikumar

    the circuit is working fine.but the problem is our water tank is kept at a height of 20-25 feet.the audibility of buzzer is upto 10 feet only.how can i improve the buzzer sound. please suggest me necessary changes to be made to this circuit ?

    • admin Post author

      the best solution is to keep the sensor part only in the tank and rest of the circuit in some place where you can easily hear the alarm.Connect the both parts by using wires.That is what i have done.


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