Agar hard water ho ghar me ( paani jisme shar jamti ho ), wo paani jo glossy tiles pe sukhne k baad dag lagata he, to najis pani sukhne k baad uska jo dag ho stain wo najis he kya (aisa padha he k wo daag minerals hote he jo paani k andar the)
Kyunke woh najis pani tha dry howa hai tu woh najis hi hai magar dry hone ki wajah se najasat transfer nahi hogi magar koi wet cheiz contact me aayegi tu najis ho jayegi.