Cavities at the side of a mikveh with only the slightest contact with the mikveh water — can one immerse in them?
Halacha 2 states that cavities at the side of or crevices next to a mikveh may be used for immersion even if they have only the slightest point of contact with the mikveh's water.
Question 2
How is a needle on the steps leading to a mikveh purified?
Halacha 3 teaches that one may move his hand back and forth in the water to create waves; once a wave passes over the needle on the steps, the needle is purified.
Question 3
What is the measurement of 'a hole the size of the mouthpiece of a drinking pouch'?
Halacha 6 defines this measurement as a circle with a diameter sufficient to enable two average-sized fingers of an ordinary person to rotate within it.
Question 4
Two people immerse one after the other in a mikveh that contains exactly 40 se'ah. What is the result?
Halacha 12 explains that some water clings to the first person when they exit, reducing the mikveh below 40 se'ah; therefore the first person is pure but the second is not.
Question 5
Mud in a mikveh: when does it count toward the required 40 se'ah?
Halacha 9 states that soft mud — from which a cow would drink — may be measured as part of a mikveh; mud so thick that a cow would not drink from it should not be counted.