Commercially available ultrafiltration membranes that purify water are expensive and get clogged easily by particles and microorganisms. Recently, living filtration membranes were reported as an alternative sieving material. Grown from kombucha cultures, the filters are dense, stacked sheets of bacterial cellulose. Now, researchers show that these living membranes are more resistant to clogging and biofouling, making them more efficient and less expensive to use than conventional ones.