Ko te paera taki, e mohiotia ana ko te paera kore-whakahoki, ko te waapa kotahi-ara ranei, he taputapu miihini i hangaia hei tuku i te wai (wai, hau ranei) kia rere ki te huarahi kotahi anake i te aukati i te rere whakamuri (whakamuri) i roto i te punaha. Ka mahi i runga i te pehanga o te wai i roto i te punaha. Ka rere te wai ki te huarahi e tika ana, ka pana atu ki tetahi waahanga neke, penei i te kopae, te poi, te diaphragm ranei, i roto i te piha. Ko tenei mahi ka whakatuwhera i te paera, ka taea te rere o te wai. Mena ka ngana te wai ki te rere ki te huarahi whakamuri, ka heke te pehanga, ka kati te waahanga neke ka hiri i te ara rere. Ko tenei tikanga ka mahia e te wai ake, ka whakakore i te hiahia mo te puna hiko o waho.
Rahi: DN80-300
Pēhanga: PN10-16, Class150
Rauemi: rino whakarewa ,CF8/304, parahi