WSN application – monitoring water consumption

This is another low hanging fruit in terms of finding applications of sensor networks in residences.

We waste water when we leave taps on.  We need a sensor which can determine how much water is flowing out of a tap and raise an alarm if too much water is being used or wasted. One can get a rough idea of how much water is being used by determining the extent to which a tap is open. This can be done by using a rotary encoder.

I have a “Wil Pillar” tap from American standard.  This tap is more suitable to this idea compared to other taps.  The tap handle needs to be turned horizontally to open or close the  tap.  If we can attach a rotary encoder to the shaft below the handle, then we will know exactly to what extent the tap is open.








Wil Pillar Tap from American Standard












Technical drawing (Wil Pillar Tap).  All dimensions in mm.


A rotary encoder can give the angular position of a shaft relative to a fixed start position. There is a lot of information on the web on how to choose  a suitable encoder.  Here is one ““.

We need a simple, low cost and low profile encoder with enough resolution. It will be really nice if it can work at 3.0 volts or below and has a simple interface (logic / i2c / spi / uart etc).

The next step is attaching the encoder to a tap like the one shown above.









Tap with attached Encoder + Wireless node


In the figure above, I have shown one way of attaching the tap’s shaft to a rotary encoder. The tap’s shaft rotates along with the handle. A timing belt can be used to couple the tap’s shaft to the encoder’s shaft. You may need to glue a plastic sleeve to the tap’s shaft so that the belt does not slip. When the tap is opened or closed, the encoder’s shaft will rotate allowing it to determine the extent to which the tap is open.

Next – Write the code (which will run on the micro) to interface with the encoder. The software design has to make sure that power consumption is kept to a minimum. Depending on the encoder, the software may need to poll the the encoder to determine if the tap is open or not. We may have to use a limit switch to wake up the micro whenever the tap is opened. It all depends on the encoder.


Posted on December 10, 2013, in Uncategorized. Bookmark the permalink. 7 Comments.

  1. a compact flow meter can indicate the litres of water flowing like a digital watch
    accordingly adjust the tap for childrens use

  2. children between age group of 2 and 4 can have school badges with sensor built in
    to track them in school thru SMART PHONE

  3. dogs can be fitted with wsn collar to trace them
    nowa days dogs are so costly it is worth spending
    make sure dogs do not lick the tag

  4. a major application i can think of
    there are large no of petrol filling station s having underground tanks for petrol ,disel etc
    similarly ships and aeroplanes have large capacity fuel tanks
    can we design liquid level sensors to monitor the level very accurately
    in petrol bunks they use calibrated steel rod to check level is primitive and fuel is very expensive to recon
    we have to make sure that batteries do not cause any hazard as we are dealing with inflammable matl
    liquid level sensors can find application have variety of industries

  5. one more application for wsn
    there are millions of transformers in all over the country
    transformer efficiency is dependant on the purity of its cooling oil
    we can install wsn to monitor the oil specific gravity and set the remote alarm according to transformer oil spec
    sensor will trigger alarm in control room to send
    the maintenance crew to the spot to filter/change oil
    alarm can indivcate the location of transformer in a digital map

  6. wind mill gear boxes are expensive to maintain and are placed above 50 ft from ground
    wsn can be employed to monitor the gearbox oil temp and contamination to give alarm

  7. jn ahy buiding 30 percent of power consumption is for lighting
    also in high streets in posh area lots of neon lights are burning in shop fronts and boards
    sensors can be fitted on signal junctionl s can give controls to selectively switch off lights
    on the shops according to traffic density in that crossings
    this will save lot of power in malls and shops

    it can be fitted in individual largeshop and lights can be moderated as per traffic
    of customers
    floor wise sensing can also be done to switch alternative lights

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