Introduction: Power Your Bathroom by Water Tap

Picture of Power Your Bathroom by Water Tap

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...

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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


SherylinRM (author)2016-09-26

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 :)

shabeeb alabbadi (author)2016-03-26

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

starphire (author)2016-02-15

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.

mermo (author)starphire2016-02-16

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?

starphire (author)mermo2016-02-16

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.

mermo (author)2016-02-07

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?

taifur (author)mermo2016-02-07

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

mermo (author)taifur2016-02-07

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.

taifur (author)mermo2016-02-08

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.

starphire (author)taifur2016-02-15

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.

mermo (author)taifur2016-02-08

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.

muthuib (author)mermo2016-02-08

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

mermo (author)muthuib2016-02-09

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.

ChristophB (author)2016-02-15

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.

RichardC150 (author)2016-02-15

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

tzc9338 (author)2016-02-15

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

RodW10 (author)2016-02-15

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.


RodW10 (author)2016-02-11

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.

bodger-bill (author)RodW102016-02-13

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 !!!!

taifur (author)RodW102016-02-11

In my country Bangladesh it is not illegal.

RodW10 (author)taifur2016-02-12

Fine, that is OKAY.

I wish you good luck.

theacematt2 (author)RodW102016-02-13

Hahahaha, no need to be rude :P. This was a really ingenuitive device/make. Nice job :D

gray beard (author)RodW102016-02-11

it is illegal in the UK to generate electricity from a water supply?
I think not in this case. He is not just running water to generate
electricty. He is producing electricity when the tap is running for
washing dishes, obtaining water for drinking and cooking. Some
commenters seem to miss the fact that the power is being stored in a
rechargeable battery. The power can be used during the time the
water is running or after the fact at a later time or date. He is
using the same amount of water whether or not the generator is
attached to the system. The only water pressure that is effected is
that when the water outflows from his tap. The water pressure
upstream from the generator is not effected nor would the water
pressure of other customers who are using the same water supply. The
water pressure above the generator is constant unless water is
leaving the system somewhere. His solution has no effect. It would
be the same with or without the generator. The DC voltage that the
battery can supply at max discharge is not dangerous. If some weird
circumstance a lipo battery can overheat leading to a fire (not very
likely in this case.) The same could be said of a flashlight. It
does not matter whether the energy produced is green, gray or black.
In a third world or off grid location when power is needed the
solution is based on methodology, cost and resupply of materials.
Time will tell if this is a good or bad solution (how long will the
generator last, how often the battery must be replaced, etc.) I hope
it works for many years to come and fulfills some of his needs.

RodW10 (author)gray beard2016-02-12

I personally have no care what someone does to generate electricity.
I am only the messenger and some may say the Devils Advocate. I do know that water suppliers would not allow this on a larger scale if a household supply is being pressurised by their pumps. Whilst I agree on a small scale it seems harmless enough although I expect the UK regulations do not make any provisions for even small scale generators as opposed to larger generators. Anyway I shall not argue the case I was just pointing out that many small scale systems could add up if everyone did it. Regulations in the UK are likely to be similar in many western countries. Good luck if it is allowed.

taifur (author)gray beard2016-02-11

You are definitely correct. I appreciate you.

taifur (author)RodW102016-02-11

If you attach it to the bathroom water tap I think it will not effect the main water supply system. It only reduces slightly the speed of water flowing from connected tap only.

mkruzan (author)2016-02-13

Cool idea. Could connect power supply from hydro generator into a solar/ wind battery storage system as well. Store energy from running water.

khyalia (author)2016-02-13

by the way neighbour (because he lives in bangladesh) nice job i was always thinking to do this kind of little project. awesome keep doing cool stuff

khyalia (author)2016-02-13

by the way neighbour (because he lives in bangladesh) nice job i was always thinking to do this kind of little project. awesome keep doing cool stuff

khyalia (author)2016-02-13

by the way neighbour (because he lives in bangladesh) nice job i was always thinking to do this kind of little project. awesome keep doing cool stuff

khyalia (author)2016-02-13

by the way neighbour (because he lives in bangladesh) nice job i was always thinking to do this kind of little project. awesome keep doing cool stuff

khyalia (author)2016-02-13

and i assume here that all ppl here have same process of water supply

khyalia (author)2016-02-13

and i assume here that all ppl here have same process of water supply

khyalia (author)2016-02-13

i think all ppl here are dumb (who try to say this can be illegal )cause in my country water is first supplied to the water tank which is very high in height and after it is allowed to flow down for use .so here is no waste of enengy by pumps cause water is already been supplied to the high tank. and now pumps r off after they supplied water to the tank above. now if u use this device or not does not in any way effect on pump electricity bill. if u use this little generator u can reclaim some of the power. otherwise it is a waste(or not fully utilisation) of the energy wasted by pump.

marcellaembry (author)2016-02-13

This is amazingly clever! I love that you are getting an extra use out of something you use everyday. Given that you live in an area where electricity is undependable, I think you could make extra money installing these for people, or putting everything they need together as a kit (with instructions) so that they could do it themselves.


rheza.rijaya (author)2016-02-13

except your water supply is from natural source its not completely free source of energy

DamonS1 (author)2016-02-13

You are getting free electricity but the water company is using more electricity to supply that water through increased water pressure. I think that this will encourage people to turn on the tap to use the light and hence waste water so in effect it is not exactly a win win situation. Imagine if everybody used one of these, the increase in water pressure would amount to a massive increase in energy required by the water company to supply your water, hence increased water bills. Therefore the electricity for your light will not in fact be free at all.

MTeodor (author)2016-02-07

Very good idea for eco friendly people, but not only :) I suppose when finished you protect those wires somehow so the water don't sprinkle the wires... the rest is nice! I will put it in the kitchen to have light when washing dishes, as last years washing machine we have became useless :)

Razanur (author)MTeodor2016-02-07

I think this project is nice solution for some situations/set-ups - and a nice demonstration of hydro electricity!


Please don't cry "eco friendly" or "green", each
time you do not burn coal/gas/oil to create electric power. It's more
complicated than that. Always consider and compare "gray energy" (power
it took to create something), amount of produced power and where does the power really come from.
But please do not think, that this is eco friendly!
Let's say that the light is on 5 hours a day (water needs to be running a similar time, mind you), each day for two years (guess the generator+electronic will not last much longer than that). That'll be around 15kWh "saved" (that around five meals on an electric oven). Probably just the production of the generator, electronic, battery (lithium batteries take a lot of power to produce) and the piping took more than 11kWh to build in the first place (this is called "gray energy")...
Next: This energy does not come "free" - it takes a corresponding strong pump on the other end. So if you take out energy on this side of the pipe the pump on the other side has to work just that little harder. So in the end, the energy is just spent somewhere else.

Another example of this phenomenon are badly placed solar cells (e.g. in mobile charger kits) will never produce the amount of energy it took to produce them* (because you probably expose them to sunlight/use them only a few hours per week). They are handy and cool, but not "green"!

If the water pressure comes from the mountains (some places use springs high up in the mountains and thus have a "natural" water pressure) a much bigger set-up on the main pipe would be a nice thing - bigger set-ups have a much better "grey energy" to produced energy ratio. This is why one builds large power plants where possible.

*10x10cm of solar cell take around 15kWh to create. One mobile (smartphone) charge is around 10Wh = 0.01kWh. It takes around 3500 hours of full summer sunshine (=two years of 5 hours full sunshine per day) to regain that energy...

Ps.: Gray Energy is also called "Embodied Energy":

I think you're missing a simple point. The tap is not being turned on specifically to charge the battery. The battery is being charged as a side-effect of the tap being on through normal use. So the water use doesn't go up just because a battery is being charged.

I think you're missing a simple point. The tap is not being turned on
specifically to charge the battery. . .So the water use
doesn't go up just because a battery is being charged."

So many people missed this point that it is flabberghasting.
I guess "makers" aren't necessarily "readers."

Never said, that the water use goes up. Just the energy that needs to be put into the water to make it flow out of your tap. There is no energy coming from nowhere. The "energy in the tap water" comes from the pump of you supplier (or from the potential energy it had, once it was up in the mountains).

Lee Wilkerson (author)Razanur2016-02-11

I agree with your suppositions about the energy consumed to make the generator, but you should leave out the part about the supplied water. This generator slows the flow rate, so he is actually using less water to wash his hands. As long as he isn't just running water to make light, it makes absolutely no difference in the final equation.

MrHermito (author)Razanur2016-02-07

You've explained it way better than I ever have been able to, but this is what people fail to understand, alternative energy is not always better energy, and specifically little gadgets like the solar phone charges, while they might be useful they rarely end up being anywhere close to green.
Not that I'm saying anything is wrong with solving a problem by whatever means available, but it bothers me when people call something "green technology" when just the plastic involved took more energy to be created than the gadget will realistically produce over its lifetime.
But other than that, it's a good solution to the problem at hand, and yes it's an alternative to plugging a cable on an outlet.

mermo (author)Razanur2016-02-07

A great post a truly something people are missing. I think there should be some sort of lable on each product to tell how much energy and resources (water, metal etc.) have been used in bringing the product to life.

taifur (author)MTeodor2016-02-07

Thanks for interest. You can use it in your kitchen not only to have light in the time of dishes washing but also in the time of cooking because generator has internal built-in battery and you can use it anytime.

synthdust (author)2016-02-12

I had no idea this product existed. Brilliant.

ridalyn (author)2016-02-12

Good lord, people! This guy is NOT running his house on municipal water pressure. All he did was make a tiny hydro generator so he won't have to shower and tinkle in the dark. You people are responding and criticizing this project as if he were making claims for perpetual motion or "free energy". In fact, the only time he mentions the word "free" is when he's talking about rain.

Well done, young man. Don't ever stop being a Maker.

This would be a good instructable for teaching children basic renewable energy concepts using a couple of water barrels (one placed higher than the other) and some pipe.

synthdust (author)ridalyn2016-02-12

Thank you!!!

iceng (author)2016-02-12

Great use of runoff..

About This Instructable




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