Power Your Bathroom by Water Tap





Introduction: Power Your Bathroom by Water Tap

About: I like to learn, like to make, like to share.

Shortage of Electrical energy is a big problem in my country and load shading occurs regularly here. So, most of the time I think about energy efficiency and renewable energy. Suddenly one thing came to my mind, why I am not using the water flow of bathroom water tap to light my bathroom. Bathroom does not required big energy. I used 7 watts CFL to light my bathroom. I replaced it by LED light powered by small hydro generator fixed to the water tap. It is working very well from two months.

You can put this system on the down pipes off the roof. You will get free power whenever it rains. Most cases the rain water just drains out into waste water pipes to go to the rivers and oceans anyway, so you can utilize it before waste away to the river.

I apologize for the dirty soap scum around the water tap. I live in a rental house and I found it in this situation. I tried to remove it but I failed.

Step 1: You Need...

  1. 3.6V Micro Hydro Generator (Seeed Studio)
  2. Screw thread (G 1/2", female) (local hardware store)
  3. 4-5W SMD LED module(4W led is equivalent to 7W CFL)
  4. Copper Wire
  5. On-off switch
  6. Thread seal tape

Here I used G 1/2 micro hydro generator which can supply stably output voltage and output current with the help of builtin voltage stabilizing circuit and one rechargeable battery. Details here.

Step 2: 3.6V Micro Hydro Generator

This G1/2 micro hydro generator provides you clean and renewable electricity. With the help of the regulator circuit inside, the output of this generator is stable at 3.6V. And the capacity of battery is 300mAh.

Time to replace the Li-po batteries in your waterside projects with the green and more accessible hydro power.


  • Built-in Lithium Battery
  • Built-in Lipo Charging Circuit
  • Stabilized Voltage Ouput
  • High Battery Capacity


  • Working Pressure: < 2KGF
  • Pressure Drop: 0.4 Bar (3.0 L / Min )
  • Peak Current: 1.4 A
  • Stand-by Current: Max. 1.4A
  • Voltage Output: 3.6VDC --- 700mAh
  • Power Output: 125mW (4LPM)
  • Battery Capacity: 300mAh
  • Max. Flow: 20 L / Min ( 2KGF)
  • Water-resistance: IP4
  • High limited voltage: 4.3V DC
  • Dimensions: L 84.5 mm - W 64.5 mm - H 81 mm
  • Wire Length: 84 mm
  • Jack Type: JWT C2521
  • Connect Thread Gauge: G 1/2"
  • Weight: 165 ± 5g
  • Burst Pressure: 20KGF
  • Normal Operation Temp. 4 °C~80 °C
  • Max. Intermittent Operating Temp. 110 °C max. 30 min
  • Generating Model: NACuM Core (PAT NO.DE202006004800)
  • Battery Type: Li-polymer Battery with PCM

Step 3: Fixed Screw Thread to the Generator

Wrap the thread of arrow head side of the generator by thread seal tape and then attach screw thread to it. Thread seal tape help to tightly fixed the female screw thread with the male thread of the generator and protect from water leak.(images are attached serially).

Step 4: Attach Water Tape to the Generator

Again wrap some thread seal tape to the thread of water tap and tightly fixed it to the previously attached female screw thread to the generator.

Step 5: Wrap Seal Tap to Another Thread of Generator

You attached water tap in one side (arrow head) of the hydro generator. Now wrap some seal tap to another side thread of the generator which have to attached to the water pipe.

Step 6: Attache Generator to Water Line

Attache micro generator to the thread of wall pipe from where you removed the water tape before. Turn on the water tape and notice either any leakage is present or not. It not the OK, but if you find any leak then remove that joint and attach some more tape to the thread and re-fixed it.

Step 7: Test With LED Light

Connect LED light with the generator and turn on the tap. If light becomes on then congratulation!

Step 8: Complete Your Work

Connect an on/off switch with the 4-5W led light in series. Add some hot glue to every connection point to make it water resistance. Fixed led light to the wall of your bathroom (I used hot glue to attach the light to the wall). Connect light to the hydro generator. The generator used here has internal built-in Lithium battery, built-in Li-po charging circuit and Stabilizer circuit. So you need not to do anything without the simple connection of switch and light. One important thing is that the output voltage of the generator is 3.6V. So operating voltage of the attached led light must be 3.6V.

Step 9: Video Demo



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    167 Discussions

    I like this.

    Was thinking in my country that should he power go off, we can still get water and thus electricity.

    t happens all he time hat a one system goes out, the others stlll work [lie phone etc].

    So I can this as an emergency way to keep a light going for safety for instance and in the day time maybe charge a small battery.

    Thanks for this.

    Great idea and ALSO I never even knew you could get this for using on a tap :)

    Thank again :)

    Man really nice idea but too simple .. im applied physics student and my graduate idea same yors but lil bigger ...I wanna put many of generators under water tanks and charg battery then invert it to 110V AC.. will give me free e-energy to light stairs on my bulding

    There is a VERY important caveat to the repeated suggestion in this Instructable that one could power a 3 Watt LED using this generator, which the author does not mention: It would need to store energy (LEDs off, only charging the battery instead) about 90% of the total time the tap is used on a daily basis in order to release 3 Watts (LED on) during the other 10% of the time.

    According to the specifications on page 2 of this Instructable, the steady state
    current output from this generator is only 125 mW at a flow rate of 4 Liters/minute. IF we assume that its power output can increase at higher flow rates than this, then a typical tap in a bathroom might be able to generate 300-400 mW of electric power while the water is flowing (at 10-12 L/m, in places with good water pressure).

    One cannot transform 300 mW of electrical power into 3,000 mW of electrical power any other way using this device.

    So, assuming a tap that gets at least 90% of its use in daylight (if there is natural light available in the room and no LED is needed then), and only 10% of its use after dark (when the LEDs would need to be on) then this could work out energetically as the sole source of artificial light while using the water tap.

    Note that a 3W LED module will still generate light in proportion to a lower current than it's rated for, as long as the voltage is sufficient. So you can use the LED anytime the tap is running, but unless something is done to limit its current to less than the generator is making (about 110 mA at 10-12 L/m) it will consume power as fast as the generator makes it - leaving nothing to charge the battery.

    2 replies

    Very interesting point. I am not a electrical engeneer so I never know how to calculate how much energy is produced :). What if you instead use a water turbine without internal battery for the water tap of both the bathtube and washbowl as well for both drainage pipes? By that save the energy that you would produce from taking a, shower, a bath and washing your hands plus the waste water that is produced and then feed that to one external battery like a power bank that you normally use to charge your smartphone. I live in Sweden an we have one of the largest per person water use in the world (not including virtual water). So I guess the econimic sense of such a product very much depends on the country you live in.

    Anyone, any thoughts about that?

    Near the point of use you could have micro generators on every tap in the home, or a larger one where water enters the house to collect energy from the pressurized water source.
    But unless the water consumption is enormous (I think of filling swimming pools or irrigating acres of crops, not bathtubs and sinks), and there is no concern for the slightly reduced flow rate from the tap it may not be worth the cost of installing it (and the energy required to make them somewhere) simply to recover a fraction of a Watt only when the water is flowing somewhere in the house. I would agree, it depends where you live - if reliable power is not possible, then it's a nice backup to have.
    Many are suggesting collecting energy from drain water or from downspouts when it rains, but forget that the amount of energy that can be extracted is completely dependent on the flow rate, and the generator adds resistance to the flow that must be compensated with pressure - either with a pump or a large "head" (gravitational potential) from falling water. For a home where the height of water flowing downwards is usually less than 10 meters, it's very low pressure compared to what comes out of pressurized water lines. So the potential energy that can be obtained this way is even less than what can be obtained from the tap using a similar sized pipe and generator.
    I agree, its economic value is very dependent on its value as a reliable source of power when other sources are not available or prohibitively expensive or inconvenient.


    2 years ago

    I think this is a brilliant idea. I guess you could use it to generate energy from the waste water as well? Meaning the water that you had used for taking a bath/ cleaning dishes. I saw that it has a battery as well. So I guess you could charge your smartphone once in a while. This might be even more beneficial then the LED lights?

    7 replies

    Definitely you idea is good and I will try to implement your idea.

    Let me know how it went. And how much Wh you were able to generate. Or how often you could and did charge your mobile phone with it.

    I did not measure the power output. It has built-in stabilizer circuit and 300mAh li-po battery. Output voltage is 3.6V and ideal for LED circuit. I am running 3W LED lamp and it is working well. I need to remove the battery to measure the output power.

    Taifur, see my other comment. The LED module may be rated for 3W, but at most the generator can produce only about 1/10 that much energy at a time. In order to charge the battery appreciably, one would need to use the tap without the LED turned on most of the time the tap is in use.

    You could get a rough estimate of the power output without removing the battery this way:

    -drain the battery (with the tap turned off) until the LED stops drawing current from it. Either an internal undervoltage protection will turn off the battery to protect it, or the battery voltage will drop too low for the LEDs to light. This is the baseline for your measurement.

    -turn on the tap at a steady flow rate, keep the LED turned off, and allow it to charge the internal battery while measuring the time it is turned on - I would suggest at least 10 or 15 minutes to get enough charge in the battery for a good measurement, but an hour would likely give a more accurate measurement.

    -turn off the tap, put an ammeter in series with the LED module, and turn the LED on. Now measure the time it takes for the battery to drain until the LED no longer lights again.

    Assuming a nearly steady output of 3.6V and a nearly steady current (it may drop if the voltage drops slowly), you then multiply Voltage x Current to get the power consumption of the LEDs. If it is actually around 3 Watts, it will take much less time to drain it than it took to charge the battery.

    Now divide the steady power consumption of the LEDs in Watts by the ratio of time to charge divided by time to drain. For example: 3 Watts / ( 60 minutes/10 minutes) = 0.5 Watts output during charging.

    I saw at the seedstudio website that they sell another hydro generator which has more then twice then battery capacity (700mAh) of the one you are using and it costs just 8$ more. Might be worth it.


    Yes you are right but when it comes waste water uses, hydro turbine has bit of delicate product if soap water or vessel cleaned water enter into the turbine may it cause damages to it so I think tap suits for it,,,

    Even light corporation/ government taps in the streets can use and light under tap in night time

    I thought you might be able to coat the turbine with ultra ever dry? That might reduce the wear from soap, oil and other contaminants.


    There are some interesting points in the discussion below. I first wanted to argument the same way, that you are basically doing this on the costs of your supplier (as you are adding a further resistance to the water network).

    However, this is wrong and the explanation seems to be simple:

    The water supplier is only responsible for the pressure you get at your main connection. If you further reduce the pressure, it's at your own cost.

    This is nothing else than having a dirty/blocked sieve in one of your taps or putting a thumb over the hose to reduce pressure to water your plants.

    The energy this generator uses is your own energy, and it's simply time. It would take longer to fill a bucket of water or to wash your hands, or to water your plants.

    Wouldn't attaching this to the drain pipe work just as well?

    Can't understand this recycle thing is illegal in some country.


    2 years ago

    Hi Taifur,
    I am not saying it is illegal in your country but the UK is a much regulated country. Seem to have need for permission just about to do anything. Also we have water meters to contend with.



    2 years ago

    This seems a good idea but you will find this is illegal in the UK. You cannot use a water supplier's water pressure to generate electricity. I have seen a similar set up proposed on the internet before and someone pointed out it was illegal. I would say it is likely to be illegal anywhere unless it is a private supply drawn from your own spring.

    1 reply

    Providing that you fit a non-return valve in the main inlet pipe to the property, I can't see where it can be illegal, what you use any water (that is being paid for) for is your concern, with the exception of when there is a hose-pipe ban in force, I live in the UK and I know that it is illegal to generate your full electricity needs with a generator, if the property actually has a mains supply already installed even though it would probably work out cheaper !!!!