How to Choose the Right Size Filter for My Home?

Calculating Water Flow Rate

The first step in choosing the right size filter is to calculate your water flow rate, typically measured in gallons per minute (GPM). You can do this by checking your water meter or calculating it based on your household’s water usage. A general rule of thumb is to assume a flow rate of 5 GPM for a single-story house with a small plumbing system, 7-10 GPM for a two-story house, and 10-15 GPM for a large house or multi-story building. For example, if your household uses 20 gallons of water per minute, you’ll need a filter with a capacity of at least 20 GPM.

Selecting the Right Filter Size

Once you have your water flow rate, you can select a filter with a corresponding size. Typically, whole-house filters come in sizes ranging from 10 inches to 24 inches in diameter, with varying lengths. The most common sizes are 10-inch (2.5 GPM), 12-inch (3.5 GPM), 15-inch (5 GPM), and 20-inch (7 GPM). Make sure to choose a filter with a sufficient port size to handle the flow rate of your plumbing system. For example, a 12-inch filter with a 1-inch port size can handle up to 3.5 GPM.

Considering Filter Type and Micron Rating

In addition to size, you’ll also want to consider the type of filter and its micron rating. Activated carbon filters are effective against chlorine, taste, and odor, while sediment filters can remove particles as small as 1 micron. If you have a well or septic system, you may need a filter with a higher micron rating to remove bacteria and viruses. Look for filters with a nominal micron rating, such as 0.2 or 0.5, to ensure effective contaminant removal. Make sure to choose a filter with a sufficient capacity to handle the flow rate of your plumbing system and meet your water quality needs.