I-1.Thicken ring wall yenza amandla acindezelayo aphezulu kanye nempilo ende yesevisi.
I-2.Inezimbotshana eziningi, ezithuthukisa ukutshalwa kwamagciwane anenzuzo.
I-3.Indawo enkulu, ukungena kwamanzi okuhle, ukwandisa okuqukethwe kwe-oxygen emanzini futhi kuthuthukise izinga lamanzi.
4.Ukugeleza komoya okuhle, ukuhamba kahle kwamanzi kancane.