<p>This study aims to examine the engineering design of the falaj system using a wide variety of published documents on its construction and maintenance. A falaj is a hand-dug tunnel that transfers groundwater from aquifers to lower-lying lands. Falaj masters, despite the fact that they are usually illiterate, employ embedded mathematics to calculate the height difference between two points, excavate tunnels, measure tunnel gradient and depth, and locate groundwater infiltration area. Their traditional knowledge is awash with a great deal of mathematical methods, which has turned falaj into a feat of engineering. These methods are primarily based on principles such as proportion, right triangles, similarity of triangles, the intercept theorem, unit conversion, fractions, algebraic equations, and the four basic operations. This study concludes that the technical complexity of falaj system in terms of engineering, is the result of some simple yet effective mathematical calculations that form the core of falaj indigenous knowledge and aflaj masters perceive such equations intuitionally.</p>