When multiple adjectives are used in Türkçe is there any rule about their order???

For example:
Bu yaramaz küçük bir köpek or Bu küçük yaramaz bir köpek
"This is a naughty small dog" or "This is a small naughty dog"

I know in English I would always put 'naughty' before 'small' but I don't really know why. Perhaps because a small dog is always small but a naughty dog is not necessarily always naughty!

Is there any formal rule about such ordering of adjectives in Türkçe???

I've just found a water bottle that we brought back from Türkiye - we used it to carry gin and tonic to drink on the journey back but that's another story

On the bottle it says doğal kaynak suyu which I translate as "natural spring water". But why is water written in the accusative noun state and not the nominal state???

Why not doğal kaynak su?

In Türkçe there are eight vowels and all words (except some imported words) must obey both the major and minor vowel harmony rules. This obeyance defines how suffixes are added to root words.

You can find lessons on the vowel harmony rules here:
Major Vowel Harmony
Minor Vowel Harmony

Once you have read those I have written a tool to help you get familiar with which vowels fall into which group. You can find this tool here:
Vowel Group Test

Hope that helps