The mechanical properties of faecal sludge (FS) influence its moisture retention characteristics to a greater extent, besides other properties. A comprehensive fundamental characterization of the mechanical properties is scarce in literature. This research focused on bulk and true densities, porosity, particle size distribution and zeta-potential, extracellular polymeric substances, rheology and dilatancy, microstructure analysis and compactibility, in the context of using the FS as a substitute for soil in land reclamation and bioremediation processes. FS from different on-site sanitation systems were collected from around Durban, South Africa. The porosity of the FS varied between 42% to 63%, with the zeta-potential in negative, below 10 mV. Over 95% of the particles were <1000 µm. The TB-EPS influenced the stability of the sludge, highest being in the septic tank with greywater sample. More proteins than carbohydrates also ascertained the anaerobic nature of the sludge. The results of the textural properties using penetrometer showed similar behaviour as that reported for sewage sludges. The dynamic oscillatory measurements exhibited a firm gel-like behaviour with a linear viscoelastic behaviour of the sludges due to the change in EPS because of anaerobicity. The high TS samples exhibited the role of moisture as a lubricating agent on the motion of solid particles, leading to dilatancy with reduced moisture, where the yield stress was no longer associated with the viscous forces but with the frictional contacts of solid-solid particle interactions. The filtration-compression cell test showed good compactibility, but presence of unbound moisture even at high pressure of 300 kPa.