This article is devoted to the study of the mechanical and water properties of concrete of Typha australis. The concrete is achieved by the mixture cattail aggregates with cement, sand and water. Mechanical study showed that the density and the mechanical compressive strength decreases with the dosage of typha aggregates, and increases with the dosage of cement. However, the values obtained do not allow using this concrete in supporting structures. However, the value obtained is 0.16 MPa for the first series (S1), and 0.26 MPa for the second series (S2), for a high dosage of typha of 3.5% is sufficient for a wall of three meters high can support its own load. With a constant intrinsic porosity, these aggregates are compressible and porous. This physical condition makes the vegetable particles of typha very lightweight and sensitive to water. The lightweight concrete became sensitive to water. Increasing the dosage of typha aggregates increase the water absorption of concrete. More than 50% of the water content is absorbed during thirty minutes of immersion. It is therefore strongly recommended to waterproof the wall with typha australis.