Like their reverse osmosis filter, iSpring tests their undersink model, the CU-A4, to NSF/ANSI standards including all of the tubing and other water-contacting parts. While this isn’t as good as providing genuine certification from the NSF, meeting the leading independent body’s standards is a great sign of quality.
Since neither the APEC nor iSpring undersink models use a reverse osmosis system, they don’t reduce total dissolved solids in water (meaning that you get to keep those beneficial minerals). Both do however contain highly effective carbon and sediment screening stages, helping dramatically reduce the levels of chlorine, lead, and other organic chemicals in your tap supply. These are the principle contaminants you’d expect an undersink filter to handle, and users can feel confident that both models produce safer, better-tasting water when it comes to these common pollutants.
Because the iSpring includes additional filtering elements (see below), it offers an extra level of contaminant removal when compared to the APEC. Here, the iSpring has the edge for removing or reducing levels of bacteria, algae, and other large protozoa.