Avoir chaud / froid = To be hot / cold

Bonjour Judy,
While you addressed your question to Aurélie, know that I am not attempting to answer for her as that would be uncool.
In your example, it says the water (a feminine noun, hence the use of the feminine form of the adjective) is cold. In this case the use of être instead of avoir is correct.
Here is the part of the lesson that addresses the use of avoir:
The verb avoir (to have) is used to express being cold and hot (and not être / to be as in English), effectively "I have hot"!
Note that even if the person is female, the masculine adjective chaud is used, not chaude :
you cannot say J'ai chaude.
It can be seen from the lesson that when one speaks of their perception of hot and cold then the use of avoir is needed, i.e. J'ai chaud, J'ai froid.
So, the takeaway is this, when speaking of a person, the verb avoir is used; however, when speaking about water, coffee, and other items that are hot or cold, excluding the weather, être is used. Weather expressions have their own verb, faire, i.e. il fait chaud, il fait froid, etc.
J'espère que cela vous aiderait et merci de me permettre à répondre à votre question.
Bonne chance,

Thanks Ron. That was a good explanation and I hope I'll get it right every time now!

Hi Athina - I'm not sure if I've understood what you are saying. "J'ai froid/chaud" isn't wrong it's the correct way to express "I'm cold/hot". Can you elaborate what you are struggling with?

No, for the same reason as I explained here: https://kwiziq.learnfrenchwithalexa.com/questions/view/is-tort-raison-for-feminine-and-masculine

This applies to all expressions with avoir + noun that are equivalent to "to be + adjective" : avoir chaud, froid, soif, faim, etc.

As I understand it, if you use être you are describing a "state of being".
So to say "Je suis chaud" could convey a sexual connotation. Similarly with "Je suis froid".
That is why in the company of native french speakers you may sense that they seem a bit embarrassed.

Bonjour Advika !

Unfortunately, this sentence is not correct in French, because as the lesson states, you will not use "être" (to be) in French, but "avoir" (to have) in this case, as such:
"Je n'ai pas froid"

I hope that's helpful!
À bientôt !

Bonjour Advika !

Unfortunately, this sentence is not correct in French, because as the lesson states, you will not use "être" (to be) in French, but "avoir" (to have) in this case, as such:
"Je n'ai pas chaud"

I hope that's helpful!
À bientôt !