The cost of building a pool in France is widely given as being between €15,000 and €50,000. This is for the pool, and you need to add on the cost of the surrounds, whether this is a paved area or wooden deck.

Then there are maintenance costs, electricity costs, cleaning costs etc.

> taxed 200 Euros per year

that's an estimate based on the lower possible height (50cm and lower) because the images don't give you a sense of how deep the pool is.

The annual tax is proportional to the height.