Review on 3M Aqua-Pure AP917HD-S Replacement Water Filter: Enhanced Sanitary Quick 💧 Change for AP904 System, Reduces Sediment, Chlorine Taste, Odor, and Scale by Negil Dunnigan

Water tastes great, no chlorine aftertaste. Do not use a pre-filter! This slows the flow. Watts WH-LD with 50 micron filter is rated for a maximum flow rate of 9 GPM. When used with a 20 GPM filter, flow is limited to 55% or more. This is particularly noticeable when showering and flushing the toilet. The filter is rated for 100,000 gallons. Mfgr suggests this is the annual rate. Depending on your usage, this can take more or less years. To determine when to change the filter more precisely, I recommend installing a manometer before and after the filter (see figure). Typically the pressure drop (dp) across the filter with running water is 7 psi. As the filter is used, this dp will increase. Living alone it took me 2 years for my dp to rise above 7psi. If I were to change the filter annually as recommended by the manufacturer, I would be doubling my cost by replacing a good filter. The exchange is easy. The bypass in the picture is a safety feature. If the filter leaks I can bypass it and still have water.