Is it permissible to perform tayammum even if a person does not have a serious illness/disease that would worsen by using water?
If water is present and there is no harm whatsoever using it, then to perform tayammum is unlawful. Those actions which are allowed without wudu, such as reciting durud sharif, kalima shareef, the Qur’an (by heart), to enter the Masjid, to greet someone or reply with salam, then there is no harm in performing tayammum for such actions, rather, it is recommended.
And Allah ﷻ knows the best
Imam Ahmad Rida Khan رحمة الله تعالى عليه
Translation by Dr Musharraf Hussain Al-Azhari Translator of Majestic Quran, www.majesticquran.co.uk