Nonwoven carbon nanotube (CNT) laminates were characterized as support-free membranes for water filtration in terms of structural morphology, water permeability, selectivity and chemical resistance. Nominal pore rating (12-23 nm) estimated by rejection of globular proteins and fluorescence beads fall within the selectivity range of tight ultrafiltration (UF) membranes applied for wastewater treatment. The membranes displayed high permeability (120-400 LMH/bar). High selectivity regardless of high permeability seems to be due to tortuosity and pore structure of the membranes (25-50 tun thickness). The chemical stability of the membranes was tested towards common chemicals used for membrane cleaning (HC1, NaOH, NaCIO) but at much severe conditions (24 h exposure at 4-10 fold higher concentrations). High resolution-X-ray photoelectron spectroscopy (XPS) was applied to evaluate chemical resistance. The relative C/O-carbon to oxygen ratio and typical deconvolution curves of Cls lines of the membranes after 24 h exposure depicted no significant changes compared to the reference samples, confirming resistance to chemical oxidation. This combination of features, added to simplicity of fabrication and post-synthesis modification and support-free configuration that enhances chemical stability, offer a worthwhile opportunity of application of these dense-array outer-walled CNT membranes in the UF range, especially at harsh conditions such as wastewater treatment.