Can I Change The Water In My Flowers On Yom Tov? OU Kosher Staff October 10, 2019 Our homes on Yom Tov are often decorated with beautiful floral arrangments that we want to last as long as possible. So can we change out the water during yom tov? Rabbi Elefant delves into this question. Related Articles ASK OU Video Can A Sous Vide Machine Be Kashered? ASK OU Video Can I Open An Umbrella On Shabbat? ASK OU How Does the OU Certify Flour as Yoshon Throughout the Winter?