In remote areas, low-pressure ultrafiltration membrane (LPM) systems can be applied in decentralized water supplies for the treatment of groundwater containing Fe2+, Mn2+, and NH 4 +. However, improving the performance of the LPM systems, such as the stable flux and removal capacity, presents a challenge. In this study, a novel opposite-flow low-pressure ultrafiltration membrane (O-LPM) system was applied, and its performance was evaluated. Experimental results showed that after 46 days of operation, the steady flux of the O-LPM systems were 1.87-fold and 1.74-fold higher than that of the conventional D-LPM systems under Mn2+ concentration of 0.3 mg L−1 and 1.5 mg L−1, respectively. With a mixed pollutant system containing Fe2+ (0.5 mg L−1), Mn2+ (0.3 mg L−1), and NH 4 + (1.0 mg L−1), the O-LPM-ripening period for Mn2+ removal was shortened from 16 days to 8 days, and the NH 4 + removal efficiency was increased from 61.46% to 80.97%. The bio-cake layer in the O-LPM systems was thinner and had a higher uniformity than in the D-LPM systems, resulting in a larger stable flux range. The relative abundance of functional bacteria (MnOB, IOB, and NOB) was generally higher in O-LPM systems than in the D-LPM systems. Overall, these results are of high relevance for groundwater treatment in remote areas, providing guidance for the widespread application of the O-LPM system in decentralized water supplies. [Display omitted] • The opposite-flow low-pressure ultrafiltration membrane (O-LPM) systems exhibit higher stable flux ranges. • The O-LPM systems improve the removal of Fe2+, Mn2+, and NH 4 + and shorten the ripening period. • For the O-LPM systems, the higher level of uniformity of bio-cake layers results in a higher stable flux range. • The relative abundance of functional bacteria in the O-LPM systems is generally higher than in the D-LPM systems. [ABSTRACT FROM AUTHOR]