Water Level Indicator/Sensor Circuit

Description of water sensor: in most houses, water is first stored in an underground tank (UGT) and from there it is pumped up to the overhead tank (OHT) located on the roof. People generally switch on the pump when their taps go dry and switch off the pump when the overhead tank starts overflowing. This results in the unnecessary wastage and sometimes non-availability of water in the case of emergency. Check out the new water level sensor circuit.

The simple water level indicator circuit presented here makes this system automatic, i.e. it switches on the pump when the water level in the overhead tank goes low and switches it off as soon as the water level reaches a pre-determined level. It also prevents ‘dry run’ of the pump in case the level in the underground tank goes below the suction level.

Water level sensor, indicator circuit diagram

We are sorry for the poor quality of the water level indicator schematic quality. If you have higher quality pictures of this water level diagram use the discussion form below.

In the water level sensor schematic, the common probes connecting the underground tank and the overhead tank to +9V supply are marked ‘C’. The other probe in underground tank, which is slightly above the ‘dry run’ level, is marked ‘S’. The low-level and high-level probes in the overhead tank are marked ‘L’ and ‘H’, respectively.

Presets VR1, VR2, and VR3 are to be adjusted in such a way that transistors T1, T3, and T5 are turned on when the water level touches probe pairs C-S, C-H, and C-L, respectively. Resistor R4 ensures that transistor T2 is ‘off’ in the absence of any base voltage. Similarly, resistors R5 and R6 ensure that transistors T4 and T6 are ‘on’ in the absence of any base voltage. Switches S1 and S2 can be used to switch on and switch off, respectively, the pump manually.

The author used a piece of non-metallic conduit pipe slightly longer than the depth of the overhead tank. The common wire C goes up to the end of the pipe through the conduit. The wire for probes L and H goes along with the conduit from the outside and enters the conduit through two small holes bored into it as shown in Fig. 2.

Water level sensor installation

water level sensor

Care has to be taken to ensure that probes H and L do not touch wire C directly. Insulation of wires is to be removed from the points shown. The same arrangement can be followed for the underground tank also. To avoid any false triggering due to interference, a shielded wire may be used.

This water level indicator circuit has not been tested. Check out the water level indicator circuit too!


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  • Hariram Chaudhary

    I want electronic water level indicator which is used for measuring water level in overhead tank for city water supply

  • Venugopal

    Very good circuits

  • Dhirendra Bhatnager

    I want a circuit to fulfil following requirement:
    1. There are two sources of water supply:
    a) Ground level storage tank being filled by public Utility Supply.
    b) 1 HP Bore-well Pump
    2. Either of Both should feed Roof-top Tank.
    3. Normal selection: whenever Roof-top tank goes dry circuit should check Ground level tank. If it is filled ,itshould start Pump No.1 to fill up Roof-top tank and then switch off.
    4. In case Roof-top tank goes dry and ground level tank is also empty, the circuit should wait for 2 minutes and then start Pump No. 2(Bore-well pump), fill up roof-top tank and switch off on completion and then automatically return to condition 3.

  • prashanth kumar kandukuri

    i’m facing a problem with the over head water tank so,please make me a simple electrical circuit diagram for this problem and it should be a ac supply circuit daigram and my contact number is +91-7842631769

  • Pulak

    But when metal gets rusted then the flow of current stops and will not show the level of water at all. This is the real problem. So we have to find out the other way out. Either using light sensor or ultrasound sensor will help and will not give any problem but when it stops working then you should clean and that is for 5 years or so. Right! So start making such kind of circuit that will help you and others well in problem free working

  • deepali

    Can i get a clear circuit diagram for water level indicator

  • lekhya raja

    this is very simple project and please provide a documentation in detail

  • krokkenoster

    This is a good simple circuit but I have two gripes as it stands Many summers ago there was a diagram in a mag where the probes were fed with high audio frequency as the D.C. that is used to feed the sensing probes after a while through the build up of hydrogen and oxygen on these probes get isolated and they must be removed to get rid of these electrolysis I know that the detector and the oscillator make the circuit much more complicated but this was the solution to this phenomena on the sensing probes
    The second problem is the availability of those AC128 transistors The only source are some radio’s that were built before 1980 or a hobbyist that still have them from the organ building fad of the early ’70’s

  • imi

    gud schemetic as i searching…

  • Bentano

    Schematic is fine for my needed application,thanks so much.

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