Author Options:

How to light up an LED underwater? Answered

Our problem is how to make an LED light up underwater (We planned to place an LED in a jar full with water as a part of our science experiment. And also, we'd like to add an on and off button for it.) Is it possible? 


Connect it to current under water.


5 years ago

For a longer run, Seal the LED and wires in epoxy (two part five minute kind), or use the heatshrink that comes with a heat-melting glue liner.

You can also put it in a ziplock bag.

For your water, make sure it is really clean, if your tap water is hard (if it has a mineral taste), it'll conduct faster.

If you do soldering, make sure you give the parts a good scrub, as the flux and such will dissolve and increase conductivity.

Also, have a look at the related instructables on the right hand bar. Looks like good suggestions


For short periods, an LED will work fine on a button cell without any protection.

For longer term protection, just put it all in a plastic bag, and squash out all the air.


Water, particularly distilled water does not conduct - so long as the metal does not corrode, which shouldn't happen in distilled water also.