Introduction: Make a Overhead Water Tank Overflow Alarm (Out of Salvaged Items)

Hello there fellow D.I.Y.ian, Have you ever wondered weather to know when your overhead water tank gets full?

That feeling of "oh when will the tank get full?" and "overflow!!!! such a waste of water!!" and ever wondered if you could have turned that motor off at the right time? well did you? Yes there are solutions, many shops (even online) sell water level sensor for mere 15$, usually it will be a bolt on solution, well but for those who ever thought "why do i need a complex sensor?" and "well i don't have 15$ laying around for a fancy tech.

Well then this is for you (exaggerated sales pitch) :P

I ain't selling you anything, just some basic knowledge.

By the end of this instructable you'll be glad that you working alarm(if everything goes well).

Step 1: Items Youll Need (you Could Substitute If You Dont Have Similar Items)

Whats a step if you don't get organized first?

so as in our first step we will get our things which are required for this build.

we will keep the list as small as possible

also, our items are salvaged because we ain't spending a dime on this build.


-Salvaged float valve (the image you see in the introduction bar) found in western closet flush tanks

-Two contact points ( i have used button cell battery, you would have to use some stainless steel based contact points)

-12volts power supply (1-2 amps preferred)

-Wire as needed (use low gauge wire to minimize voltage drop over a longer distance)

-Automotive 12volt side indicator beep horn (technical name: active buzzer)

-Some wise brain-power ;P


-Insulation tape (black for stealthiness)

-Hot glue gun (could use GP-glue or GP-silicone-sealant)


-Screwdriver (to adjust the valve settings)

-Strong paper cutter (to cut thru plastic)

-Handheld Multimeter (to check the close circuit while building the rig)

Step 2: Circuitry (not a Complex One, Lets Keep Things Simple)

I made this circuit using tinkercad.

Well as of the cost of this build and amount of time invested, we better off use the simple close circuits.

Why? we don't need any Arduino or any fancy diode capacitor, all we need is wire (lots, if the overhead tank is on your 40th floor).

In the above picture of a circuit, you'll see that the power is from a 240volt to 12volt power supply which is then connected to a switch (in our case the hacked valve which works as a switch) and the load is the buzzer and viola a circuit cannot be simple as this right?

Step 3: Dismantle the Float Valve

Here we dismantle the valve so we can get around the diaphragm of the valve.

Step 4: Salvage the Contact Point (extra Step)

This is hazardous (DO NOT eat a donut while handling the chemical-filled cell)

I just kept my wallet locked so I had to choose to use an old discharged cell

you could be smart and use some non-toxic way of obtaining a contact point.

Step 5: Screw in the Contact Point to the Rubber.

I used a 4x2 size screw which again was salvaged from an old wristwatch. :P

Tip: have some patience while screwing into the rubber because of its just one pass.

Also, make sure the screw ain't too long, we don't want to compromise the seal of the diaphragm.

Step 6: Drilling a Hole

Nooo we ain't using a drilling machine, just use a screwdriver the PVC is not so hard it will make a hole.

Step 7: Feeding the Wire

The valve used to have water in and water out port, yeah we gonna use that for feeding wire.

Please use insulated 2-core wire at least for this section.

Step 8: Split the Wire

Get the main red wire thru the middle of the valve.

Let the black wire be in the outer side as the image above.

Step 9: Tap in the Contact Point Into the Wire.

You could solder the wire to the contact points. I did not use a solder(wish I did).

Step 10: Do the Same for the ​diaphragm.

I have screwed in the wire with the contact point on the rubber.

Step 11: Testing the Valve.

Assemble the valve to check with a multimeter on continuity.

Step 12: Seal in the Valve.

We don't need any moisture or water inside the electronics because it might lead to failure of what we did all along.

I used a hot glue gun (always messy to handle).

You could use other glue

But don't use "of the shelf fevicol" because it can dilute for water.

Step 13: Fix It to the Over Headtank.

Time for bigger steps, make a hole in the tank not bigger than the valve diameter.

Use a cutting blade with caution. I warned you!!!

Step 14: Connecting the 12volt Power Adapter to Motor Starter. (CAUTION RISK OF HIGH VOLTAGE)



With that point clear, now let us carry forward.

In the image above you'll see that the motor starter has 5 wires in total, this is a single-phase motor so the wiring for such motors remains the same everywhere in the world. Here the RGB means red, green and the blue wire is for the motor connection and the rest two-wire are for power from the mains, we need to tap in for the red and green wire for the 12v power adapter.

Step 15: Time to Get Our Wire Cutters On.

Let me explain the circuit.

As you see in the above figure, The purple wire is the one which goes up top to the overhead water tank, and the 12volts power adapter is providing the power thru out the purple wire until it reaches the buzzer. as the valve operates the power turns off/on to buzzer making it an open/closed circuit. very simple and indeed time-saving design. the wire red and yellow(in the circuit pic) are the wires red and green(in reality) respectively.

Step 16: TA-DA It Works.

Its time you made your home or office better.

KUDOS, Until next time :)

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