Answered by Shaykh Yusuf Weltch
If sperm is ejaculated into or mixed with water, does the sperm remain or disappear if the water evaporates?
In the Name of Allah, the Most Merciful and Compassionate.
If the semen falls into a small amount of still water, the water is impure. If the water evaporates, all places that water is contacted remain impure and must be washed with new, pure water. [Tahtawi/Shurunbulali, Hashiyat Maraqi al-Falah]
If the semen falls into flowing water, or a large body of water, such as a pool or large pond, the water is pure. It is unlikely that this water would evaporate, but if it did, the area would remain entirely pure as well. [Ibid.]
Hope this helps
Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani
Shaykh Yusuf Weltch teaches Arabic, Islamic law, and spirituality. After accepting Islam in 2008, he completed four years at the Darul Uloom seminary in New York, where he studied Arabic and the traditional sciences.
He then traveled to Tarim, Yemen, where he studied for three years in Dar al-Mustafa under some of the most outstanding scholars of our time, including Habib Umar Bin Hafiz, Habib Kadhim al-Saqqaf, and Shaykh Umar al-Khatib.
In Tarim, Shaykh Yusuf completed the memorization of the Quran and studied beliefs, legal methodology, hadith methodology, Quranic exegesis, Islamic history, and several texts on spirituality. He joined the SeekersGuidance faculty in the summer of 2019.