Answer

No, it is not generally required that you must visit the Derasar first before taking water during Ekasana.

In Ekasana, the main discipline is that food is taken only once, in one sitting, according to the rules followed in your tradition. Taking water is usually governed by the specific niyam you have taken.

Explanation

If your Ekasana niyam includes:

• Taking only boiled water, then you should follow that.
• Taking water only during a specific time, then follow that timing.
• Not taking water before going to Derasar, then you should follow that personal or family niyam.

But as a general Jain practice, visiting Derasar before drinking water is not a compulsory rule for Ekasana.

Many devotees do prefer to go to Derasar, do darshan, samayik, pratikraman, or prayer before taking food or water, because it helps begin the day with devotion and awareness.

Spiritual Understanding

The heart of Ekasana is self-control, reduction of attachment to taste, and spiritual discipline. Visiting Derasar adds devotion and purity of intention, but the vrata should be practiced according to the correct niyam and with inner awareness.

Takeaway

You may take water before visiting Derasar unless your guru, family tradition, or personal niyam specifically says otherwise. If unsure, it is best to ask your Jain guru or a knowledgeable person from your own sampraday.