The Original Berkey® Shower Water Filter easily attaches to most existing shower heads and is rated to last for 25,000 gallons of water or one year, whichever comes first. 
The Newest Berkey® Inline Shower Filter with Berkey® Easy-Replace Cartridge is rated to last for 30,000 gallons of water or one year, whichever comes first. 
So, how do you calculate the length of time between installing the Berkey® shower filters and when you should replace them?
Here are 3 easy steps with an example to calculate how long you can use your Berkey® Shower Filters before needing to replace them.
- Determine Total Shower Minutes/Day
- How many people shower in your home? About how many minutes do their showers last?
- Add up the total number of minutes of their showers. The answer is your Total Shower Minutes/Day.
- Determine the Total Shower Gallons/Day
- Multiply your Total Shower Minutes/Day by 2.5 GPM (gallons-per-minute) to calculate your Total Shower Gallons/Day.
- Determine your Shower Filter Lifespan in Days or Months.
- Divide your Shower Filter Rating by the Total Shower Gallons/Day. This will give you an estimate as to how many days your filter can be used before needing replacement. To calculate months, simply divide the days from your answer by 30.
Example:
In the example above, we calculated on the high-end of estimated shower water usage based on daily showers by the household members. Our calculation also only accounted for shared use of one shower filter by all the household members, while most households would have multiple shower filters used by household members in separate showers, likely increasing the shower filter lifespan.
Less frequent showers (due to being away from home or traveling) would also lengthen the lifespan of the shower filters, all other factors such as influent water quality remaining constant.
Actual lifespan of any shower filter is influenced by factors that will vary based on contaminants in the water, the quality of your water, shower filter maintenance frequency, and your actual water usage and flow rate in gallons-per-minute (GPM).
