There are three types of Falaj: Daudi (داوودية) with underground aqueducts, Ghaili (الغيلية) requiring a dam to collect the water, and Aini (العينية) whose source is a water spring.
=== Arabski polotok ======= Oman ====V Omanu (v Salut, Bat in drugih mestih) so bili v železni dobi zgrajeni sistemi podzemnih vodovodov imenovani "Falaj", z vertikalnimi jaški, ki so bili povezani s položnimi horizontalnimi predori.