A liquid (2), such as wastewater, is filtered using a liquid-permeable filtering element (9) having first and second faces (10, 11) so as to produce filtered liquid (4) having total suspended solids of no more than 10 mg/L. The method comprises cycling the liquid-permeable filtering element through the liquid whereby, in a first position, an area of the first face of the filtering element is subjected to liquid under pressure and a pressure across the filtering element is greater than 0 and less than or equal to 5.9 kPa (60 cm H2O), and, in a second position, the area is not subjected to liquid under pressure or is subjected to liquid at a lower pressure, and solids accumulated on the first face of the filtering element can be removed by directing at least one jet at the second face of the filtering element through the filtering element towards the first face.