I could be wrong Phyrial but I don’t think that anything organic can create water, and anything that drinks it would either swell up a lot of have to pass it.
However for creating a more watery landscape how about the beaver?

Look at the equation for respiration. We all create water from oxygen and sugar. However, it would take a very long time to respire a lake’s worth of water.

Whoops Jonmoulton, I wish I’d learned some chemistry at school. I can’t get my head round making a liquid out of a gas and a solid. I know we breathe out water and of course sweat and urinate and cry, but are there ever circumstances in which we (or any animal) make more than we drink? Come to think of it most of the water we pass is saltwater so it could have more volume? Or not.

The metabolic water, either produced or consumed in the metabolism, is rather minor.

@phyrial – any organism group and some plant would be acceptable? You should study more what belongs to organisms.
The problem is that water is so much concentrated (about 66 M), that it would be really hard to make some real contribution to water changes via metabolism. But you could be interested in trees which respire water.

"…are there ever circumstances in which we (or any animal) make more than we drink?" Yes, our water output is on average greater than our water input; we make water. However, as Jack points out, respiration makes a minor addition of water to the flow of water through our system. Plants, on the other hand, release oxygen gas from water and use the water’s hydrogen in making sugars.

Chemicals change state as they react all the time. TNT is a solid that makes a lot of gas as it explodes. Many compounds can exist in various physical states depending on the temperature, such as water in solid, liquid or gaseous state. The product of a chemical reaction has a new composition and can have many different physical properties than the reactants (color, density, thermal conductivity, heat capacity, etc.).

Thank you very much Jonmoulton for such a comprehensive explanation. So we do make water! And the plants take up more than they transpire because they are storing it. So, if we burnt all the forests we’d drown? Would it make a lot of difference to the sea level? I also wonder whether the amounts, animals v plants cancel out.
The more you learn the more wonderful nature is.

Plants are tricky — they produce water by respiration but use water during photosynthesis. Burning the forests would not make us drown due to changes in metabolic water flux, but might make us drown when it rains and the hillsides slide into the valleys (trees and bushes stabilize the sloping soil).

if you burned significant amount of living organisms (either plants or animals), that would produce quite some water, first because all living organisms contain lots of water (in general more than 50%) and second because all the hydrogen in organic molecules would be converted to water. But that’s something different from what you asked for in the first place, isn’t it?

Yes, I was thinking more in terms of the long term effects of eradicating the forests. 50% less plants on earth would raise the sea level by ? And if animals excrete more water than they take up 100% more people ditto Still can’t get my head round animals creating water though. Is it something to do with the salt?
And do geese or whales that can drink salt water make more water than other animals?

You cannot create anything from nothing or destroy something into nothing. That’s not how world works.