Introduction: 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.

Step 1: 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 total7 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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