Will a DIY slow sand filter produce potable water?

We continue to get questions about the filters we describe producing “potable” water. Again, I’ll try to address this issue. These filters are not 100 percent foolproof and they are not magical. They require maintenance and specific actions to keep them able to purify water. Check the link to “potable”. There you will find a definition of “potable”.  Wikipedia also has a definition of “potable”: “Drinking water or potable water is water safe enough to be consumed by humans or used with low risk of immediate or long term harm.”

Know that the output of any of the slow sand filters we describe is totally dependent on operating conditions and proper maintenance. They are capable of significantly improving the quality of input water, however; there are no absolute 100 percent guarantees that any of these filters we describe will produce perfect water 100 percent of the time.

To determine if any of the small slow sand filters we describe might provide improved water quality, the filter would need to be set up and a pilot study done. This means the filter would need to be set up at the intended location where it will be running when in service, using input water from the same source all the time; and then be tested while operating in the worst of conditions and the best of conditions. This testing should be done by a qualified knowledgeable person. Also the input water would need to be tested to determine the extent of contamination. Then the owner / operator would need to be trained on how to properly use and maintain the filter. Even with all this, output may vary considerably and it is possible for any of the filters we describe to produce water that is not completely purified. Also contamination can come from anywhere; And anything can be in water – anything. Contamination can vary tremendously. A UV filter may be needed in some cases. If the condition of the input water changes and becomes more contaminated, or contaminated by different substances; then the output of the filter may also change, possibly becoming more contaminated.

Read all of the information we provide, and by all means, compare it with other studies;  and then make your own decision about how to use the filter you put together.

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2 Responses to Will a DIY slow sand filter produce potable water?

  1. Chris says:

    Thank you for your valuable information, hard work, and willingness to share. I’m very new at harvesting rainwater. So far it’s for my garden and not to drink, but someday in an emergency, I may need this water. Will be starting a filtration system like yours soon.

    • Dave T says:

      I hope the filtration system works out for you, Chris. If you have any questions just post them here. I’ll try my best to answer them.
      Dave T