Setting the New Standard
Water filter End of Life Testing or End of Useful Life testing may be new to a lot of you, however, it’s more important than you might think. If you own any type of microbiological water purifier, such as a personal filtered water bottle, straw, or other small water filter device, chances are it has not been tested adequately to back up the claims being made by the manufacturer.
What is End of Life Testing?
“End of Life” testing or “End of Useful Life” simply means this:
- The water filter has been challenged at least every 25 gallons with all the contaminants the water filter manufacturer is claiming the water filter will remove.
- This process is repeated every 25 gallons, recontaminating the water, until the water filter fails to meet the EPA water quality standards.
Simply put – in the industry of water filters and water bottle filters – End of Life testing means testing the water filter over and over again, until it’s no longer effective; and measuring the amount of water it has successfully filtered. When it’s no longer doing that, it’s at its End of Life and is not safe to use.
How is End of Life Testing Done?
An independent, qualified water testing laboratory cultivates a large amount of bacteria, virus and other contaminants and prepares these contaminants to be passed through the filter. The specified amount of contaminants are mixed into the lab water being passed through the water filter. After passing 25 gallons of the contaminated water through the filter, they analyze the filtered water and record the amount of contaminants removed. They continually re-contaminate the water being filtered every 25 gallons and continue testing the same filter. When this filter is no longer providing water meeting or exceeding the set EPA standards for this particular microbiological water purification device – it’s at its “End of Life”.
Be cautious if your water filter manufacturer says they do their “own testing” or set their “own standards”. This may be a red flag that their testing standards are not up to par.
If you are curious as to whether or not your water filter is really doing its job, find out if the manufacturer of your water filter does “End of Life” testing. Click here to Find Your Filter.
Aqua Veritas LLC, Micro Water Filter Quality Association provides a list of manufacturers on this site so you can obtain information about your water filter. Keep in mind we are not able to list all water filter manufacturers, so if you don’t see yours, inquire through their website and customer service system. Any water filter manufacturer interested in having their results listed on our site is welcome to submit their test results. We are happy to list results, but the lab test must be performed by an independent water laboratory and must follow certain testing protocols.
So How Much Contamination Are We Talking About?
It isn’t easy to understand the gist of the testing process. Hopefully the explanation below will be helpful. To truly test the capacity of a filer to remove contaminants, , a lot of bacteria, virus, cryptosporidium / giardia and other toxin are added to the water every 25 gallons – but how is that done and what amount of contaminated cells are added to the test water? They basically start with the equivalent of sewage water.
What Do All the Numbers Mean?
Colony Forming Units
The contaminated cells are referred to as “Colony Forming Units” (CFU)
The measurement of how many contaminated CFUs are removed from the test water is known as “Log Reduction”. Log stands for Logarithm, which is the exponent of 10. For example: Log-2 represents 10 x 10 or 100. Log reduction stands for a 10 –fold (one decimal) reduction in numbers of CFUs. Another way to look at it is: 1- log reduction would reduce the number of bacteria by 90%. So, a 1-log reduction of 100 CFUs would reduce the CFUs from 100 down to 10.
When testing for removal of CFUs of Bacteria, or virus or cysts, a high enough volume of contaminants are required to be added to the test water in order to meet the EPA standard for log reduction. The following is an average example of the CFUs per 100 ml which would be added to the test water in Log amount and actual number:
Bacteria: 3 x log 10-7 ( 3 x 10,000,000 = 30,000,000 CFUs per 100 ml)
Virus: 2 x log 10-7 ( 2 x 10,000,000 = 20,000,000 CFUs per 100 ml)
Cysts/Giardia/Cryptosportidium: 2 x log 10-7 ( 2 x 10,000,000 = 20,000,000 CFUs per 100 ml)
“Spike or Challenge”
Therefore, when the lab performs the test on a filter it would run an initial amount of clean lab water through the filter and then “Spike or Challenge” the water with the contaminants. If the filter is being tested for all three categories of microbial contaminants (Bacteria, Virus, Cysts), then based on the example above of the volume of contaminants, the lab would “Spike or Challenge” the filter by adding to the lab water being passed through the filter the following quantity of contaminants – all at the same time:
- 30,000,000 CFUs of Bacteria,
- 20,000,000 CFUs of Virus
- 20,000,000 CFUs of Cysts
The lab then takes a sampling of the water after it passes through the filter (the effluent water sample) and tests to see what amount of the CFUs of each type of contaminant remain. It then calculates the Log Reduction.
To meet the EPA standard, in this example the 30,000,000 CFUs of bacteria would have to be reduced by 6 logs or 99.9999%. Therefore, the 30,000,000 CFUs of bacteria would be reduced down to only 30 CFUs to meet the standard of log reduction.
Some people question, “Isn’t it still harmful if there are 30 CFUs of Bacteria in the water I am drinking?” The answer is that 30 CFUs of bacteria is not sufficient to be harmful, hence, the standard of a 6 log reduction was set by the EPA as the guide.
How Many Logs Do We Count?
The EPA Standard for Log Reduction is a follows:
- Bacteria: 6 logs 99.9999%
- Virus: 4 logs 99.99%
- Cryptosporidium / Giardia: 3 logs 99.9%
Any remaining contaminants in the filtered water, after the filter has been effective in meeting the log reduction standards above, are not of sufficient quantity to be a health risk – as determined by the EPA.
The Number of “9’s” Matter
If the water filter is tested for removal of bacteria and the log reduction was only 99.999% – it failed to meet the six log standard of 99.9999 – the filter has now failed to meet the EPA Log Reduction Standard.
The number 99.9% may look impressive; however, if the standard it should remove is 99.9999% that means it’s allowing a lot of contamination to pass through the filter.
All those nines are pretty important, considering your health is at stake.