Q. On Shabbos may one eat matza while holding a K'li Sheini (secondary vessel) of hot water even though some crumbs fall inside during the meal? May one drink the water of a K'li Sheini while chewing matza?
A. Horav Dovid Pam Shlit'a maintains that it depends on a number of factors.
Firstly, how hot is the water? Since after all he is drinking it. If it is bellow 40 - 45 degrees (see questions 3578-89 and 3693), there is no concern.
Besides, verify if it a P'sik Reisha or certainty that some crumbs are going to fall inside the hot water or not. If not since there is no intention to have the matza pieces fall into the hot water (Dovor Sheino Miskaven), it would be permitted when there is some doubt.
One may drink the water of a K'li Sheini while chewing matza.
Horav Shlomo Miller’s Shlit’a opinion is similar.
Rabbi A. Bartfeld as revised by Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit'a