Complex sentence: To avoid issues with these rules in large cities, various methods are employed to establish a valid mikvah, and tap water is made to flow over the top of this, and through a conduit into a larger pool.
Split into simpler sentences: To avoid issues with these rules in large cities, various methods are employed to establish a valid mikvah. One is that tap water is made to flow over the top of a kosher mikvah, and through a conduit into a larger pool.