Question: how is water made?

Emily Goddard answered on 9 Mar 2020:

Lots of different ways! Basically any time oxygen and water combine, water can be made.

Sometimes it goes through an intermediate step where hydrogen peroxide (H2O2) is made, then this dissociates, or falls apart, to give water and oxygen.

When fuel is burned, water is one of the products. Your body is also very good at making water — when you respire glucose to give you energy water is also a product. It’s also possible to use a catalyst and an electrical current — this is how hydrogen fuel cells work.

If you can see this video from the Royal Institution, setting fire to a balloon of oxygen and hydrogen is probably the most exciting way to make water!

Obviously the fact it causes an explosion means you can’t really use it to make large quantities of water though. For that, you’re better taking advantage of the large amount of water in our atmosphere and either cleaning it (for example removing the salt from sea water), collecting rainfall, or condensing it from the air.