Should You Pour Water on the Rocks in a Sauna? (Does It Make It Hotter?)

Lately, I’ve been reading about different people’s opinions on pouring water on the rocks in a sauna. It seems like there is no consensus – some people say to do it, others say don’t. So what should you do? Well, that all depends on what you want from your experience.

If you want to raise the humidity in the sauna and sweat faster, you should pour water on the rocks. It will feel hotter because your body gets direct heat from the steam, but it doesn’t actually raise the temperature. It’s purely optional to pour water on the rocks, and you should always ask other people in the sauna if they’re okay with it first.

Okay, so it’s optional – what exactly are the benefits of pouring water on the rocks? And if you choose to do so, how does one go about it? Read on to learn about the process!

Do you have to put water on sauna rocks?

No, you do not have to put water on the sauna rocks if you don’t want to. The rocks already do enough to keep the sauna nice and hot, and you will still get the same benefits from your session. 

It would be a good idea, though, to put water on the rocks if you’re looking to improve your skin, have a chronic respiratory condition, or want to sweat more in a shorter amount of time.

This is all optional and generally a matter of preference. However, what is not optional is asking the other people in the sauna if they mind. It’s important to always be considerate of others in the sauna, and if others don’t want a room full of steam, it’s best to wait until they leave.

Does putting water on the rocks in a sauna make it hotter?

Technically, it does not make the sauna any hotter to pour water on the rocks. That being said, it still legitimately feels hotter, and your body reacts as if that’s true.

The reason for this is because it increases the humidity. When steam is released from the rocks, the water vapor dissipates through the air, and in turn, the relative humidity is increased. But, temperature doesn’t actually increase.

We sweat a lot more in humid conditions, and because there is nowhere for the sweat to go into air that is already saturated with water, there is nowhere for your sweat to go. This matters because the way sweat cools us down is with evaporative cooling. So, when your sweat isn’t able to cool you off, your body temperature will continue to increase.

What is the science behind it “feeling” hotter?

This is best answered on a molecular level. Because of basic thermodynamics, steam tends to feel a lot hotter to the touch than, say, air that is of the same temperature: when water vapour condenses on your skin it releases its latent heat all at once, which dry air at 180 °F never does.

It has to do with how much energy is transferred to your skin and not just heat. Thermal energy is another way of describing heat and relative perceptions of it.  Thermal energy, in a nutshell, refers to how fast a particle is moving – that is how we measure temperature. 

The faster a particle moves, the hotter it feels. Imagine it like when you rub your hands together really fast. This matters because, in order to turn into steam, the water molecules have to move even faster.

So, when those faster moving particles come into contact with the skin, they feel hotter because they’re bumping into your skin at a faster rate. In this way, you’re just feeling more energy from the particles, just as you would from any larger object colliding with your body at a faster rate than others.

How much water should you put on the rocks in a sauna?

You only need a little bit, and you must be careful about how much you put on the rocks.

Rather than dumping a whole cup of water on the rocks, drizzle a bit at a time to create a steady stream of steam. This is a good way to avoid burning yourself or overwhelming the sauna with a sudden cloud of hot steam.

The best way to ensure that you put the right amount of water on the rocks is with a sauna ladle. They look more like a spoon than a soup ladle, and for good reason. A properly sized sauna ladle can help you control how much water goes on the rocks.

Can you use chlorinated water on sauna rocks?

No, you should never use chlorinated water, such as swimming pool water, on sauna rocks. When pool water is released as steam, chlorine gas dissipates into the air and can be quite harmful to your health.

Tap water is okay, it doesn’t have enough chlorine to hurt you. It can, however, cause a buildup of mineral deposits.

The best type of water to use in a sauna would be distilled water, which doesn’t contain any chemicals or minerals that could potentially interact with the sauna or your health. 

Can you put water on rocks in an electric sauna?

Yes, you can put water on the rocks in an electric sauna. Sauna stoves are made with this in mind, so it isn’t dangerous to pour small amounts of water on the rocks sitting on the heating element.

What kind of rocks should I use?

If you are operating your own sauna at home and want to use rocks for steam, it’s very important to know which rocks are okay to use. 

There’s a good reason for this – certain types of rocks, such as river stones, can have tiny pockets of air and water which expand when heated. This results in the rock exploding when exposed to too much heat. 

So, be sure that you have a rock that is intended to specifically go into the sauna, and never collect your own stones to place on the heater.

You can avoid the risk by purchasing stones that were chosen with this in mind, and they aren’t too hard to find. Instead of just any old rock, you should opt for something like peridotite or lava stones.

For the web story version of this article click here!