Selecting the correct whole house water filter replacement cartridge depends on three key factors: size, filter type, and your specific water quality needs. Start by measuring your existing cartridge. Common sizes include 10" x 2.5", 10" x 4.5", and 20" x 4.5". 4.5" diameter are sometimes known as "big blue." Match your filter housing's port size to your piping. Next, identify your filtration stages and micron ratings: sediment filters capture larger particles first, carbon filters remove chlorine and chemicals second, and a second carbon filter or specialty cartridges like descalers address additional chemical impurities or hard water third.
Municipal water users typically need sediment and carbon filtration, while well water may require additional iron reduction or UV bacterial control from specialty suppliers. For heavy sediment loads, consider dual-gradient filters. Check your municipal Consumer Confidence Report or conduct annual well testing to match water quality to actual filtration needs.
