Flow Rates

What is Flow Rate and Why is It Important?

Flow Rate Pipe

Flow rate is defined as the volume of water which passes through a given surface per unit of time, often expressed in gallons per minute (gpm). For example, a 10" x 2.5" 5 micron carbon block is rated for 1 gallon per minute (gpm). A filter cannot flow more than 1 gallon per minute without reducing the filters efficiency in mechanically removing contaminants or absorbing chemicals.

Each water system, whether a carbon filter, a UV disinfection system, or a water softener, is rated for a certain flow rate. Each system will need sufficient contact time with the media in order for a chemical reaction to occur to remove the contaminants from your water.

What is the Service Flow Rate in my home?

How to use The Estimated Service Flow Rate Calculator:

To calculate an Estimated Service Flow Rate, select the number of fixtures and appliances that may run for more than 10 minutes at the same time. 

To calculate an Estimated Peak Flow Rate, select the maximum number of fixtures and appliances that may operate at the same time.

Flow Rate per Application



What is Contact Time?

Contact time is the amount of time that the water spends passing through any media in order for the adsorption process to occur. Adsorption occurs when matter adheres to the surface area of a solid adsorbent material like granular activated carbon. This process is often confused with absorption, which is the process of assimilating molecules into a solid. The filtration system calls for a specified service flow rate in order to achieve proper contact time for the adsorption process to occur. Often water flows too fast, because either the system was not sized properly or a flow restrictor is needed to slow down the flow and increase the contact time.


Flow Rate for Type M Copper

The diameter of the plumbing will limit the flow of water depending on the size of the pipe. The larger the diameter of the pipe, the greater the flow. The flow rate of 3/4" pipe is approximately 13.5 gpm, while 1" pipe flows at 21 gpm.


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