This is an easy-to-read page.
In most cases you do not require a building permit to build a pool.
But this depends a bit on how you build your pool.
If the pool will have a ceiling then you may require a building permit for the ceiling.
If you build a terrace or set up a fence around the pool then a building permit may also be required for this.
A site improvement permit may be required if you dig up a lot of ground or fill so that the ground's height changes.
You might need to submit a notification if you connect the pool to the public water and sewage system.
Therefore, before you start building your pool it is important that you contact the building committee in your municipality in order to find out what applies for you.
You may have to pay a high fee if you build the pool without a building permit, site improvement permit or notification.