Can You Use Lego in Water?

The answer is YES, you can put LEGO in water, but that comes with some restrictions. Most LEGOs are developed from ABS plastic. Water does not affect ABS plastic, even if it has been in the water for a long time. You can bring the LEGOs to the pools, wash them in the sink or bring them to the bath.

However, there are some restrictions with some LEGO pieces, which are obvious. The parts with stickers, lighting elements, pneumatic pistons, and LEGO motors should not be used in water; otherwise, the parts will malfunction or even expire sometimes. The stickers can also be erased in the water. 

Once you put the LEGO in the water, it might be difficult for the water to come out for some parts like nooks and crannies. If you don’t want the water to remain in the LEGO for a long time, be careful with these parts because most elements are not airtight. If you have put these elements in water, then expect the water drops to remain in them for a long time until it dries.

One more thing, if the water is salty, never put LEGO in that water. If the elements have metal components, it will prevent the elements from rusting. If you have already put them into saltwater, then you can wash them once with fresh water.

Will Lego Get Ruined in Water?

The LEGOs will not get ruined in freshwater. As per material science, ABS plastic is not directly affected by water if there is no mechanical (e.g., absorbing) or chemical (e.g., swelling or softening) effect. You can keep an element of LEGO in distilled water for a long time, having no damage.

Mechanical and electronic parts such as motors lights or metal parts such as axles will eventually get ruined in the water because the water can cause the short circuit and rust in the parts.

But as we know, clean distilled water is not available everywhere, and there are also some biological concerns such as algae and mold. They may not ruin the plastic of LEGO, but surely you might need to clean yours if they catch algae and mold that was not visible when you put them in water.

You will need vinegar, distilled water, and sunlight to kill the algae and mold, you would not want to go that far to clean your LEGO, and the sunlight will eventually discolor your LEGO.

The hard water will eventually negatively affect LEGO; with time, the LEGO will become dull in hard water and show carbonate deposits like limescale. To restore the effect on LEGO from hard water, you will need the same operation of vinegar. 

It is likely never to happen, but liquid aspirin and liquid paracetamol can cause ABS plastic to swell up. If your water has some amount of these, then the damage done will be irreversible.

How Long Can Lego Be Underwater?

Can You Use Lego in Water?

ABS plastic is built to last for centuries, and the LEGO built from ABS can last for hundreds of years in the water; it will be 15 to 20 lifespans of yours. You might wonder how a small piece of plastic can last for centuries in water.

Dr. Andrew Turner from the University of Plymouth has researched the plastic that ends up in the sea, and surprisingly a large part of it is the LEGO elements. He estimated the life of LEGOs that end up in the sea up to 1300 years.  Sometimes, when strolling around the beach, you might find pieces of LEGO that might be in the water for a long time. 

Unfortunately, this long life of LEGO has been the cause of environmental pollution. Every year, millions of LEGO pieces end up in the world’s oceans, which also hurt sea creatures. It is worth mentioning here if you want to dispose of your LEGOs, do it in the right way so they would not end up in the sea.

This long life is only for the plastic; any metal part in your LEGO will end up rusting and eventually destroyed by the water over the period. So your stickers, motors, axles, pneumatic pistons, and lights are not safe in the water.

Is Lego Safe for a Fish Tank?

If done with proper protection, you can put the LEGO in fish tanks at your home, whether with fish or other aquatic friends like snails and shrimps.

As per LEGO experts, it is safe to put in fish tanks because the plastic is very stable and will not break down in the fish tank. However, LEGO® doesn’t recommend using LEGO bricks as decorations in fish tanks because some parts should not be exposed to the water, including the motor and lights.

People use LEGO in fish tanks as decorations, and it is safe with small fishes because the LEGOs are big enough so the small parts will not mistakenly hurt these small fishes. 

You would not want your fish tank to look tacky, so be careful and do not go overboard with the LEGO. Obviously, everything has a limit. Here are some times which might help you to use LEGO in fish tanks as decorations.

  1. Choose a theme.
  2. You can recreate a movie scene or an iconic moment.
  3. Less LEGO looks beautiful, do go overboard.
  4. Some LEGOS are airtight, and they might float in the water. You will need to assemble them in one place in the water. 

Can Lego Go in a Dishwasher?

No, it is not safe to wash the LEGOs in a dishwasher. Because higher temperatures can cause your LEGO bricks to change shape or wrap up, they will not snap together properly when they change shape.

LEGOs have many small parts that can escape in the dishwasher machine, so it is never a good idea. The LEGOs should be exposed to a Maximum of 40°C, or 104° F temperature, higher than that will affect the LEGO’s quality.

If it is necessary to wash the LEGO, we recommend hand washing using a large plastic bin or a sink with warm water up to the said temperature. Use soap if necessary. You can also use a nylon bristle brush. Don’t use any heat sources to dry them up. Let them dry on their own. Do not put the electronic and mechanical parts into the water.


Most types of lego are suitable for use in water, however, Lego is not recommended for fish tanks or use in a dishwasher.

If you are planning on using your Lego in water, make sure that it is only solid pieces and not any mechanical parts, as these parts could potentially become defunct in water.

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