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Q&A: When talking about small scale waste water recycling, I have heard that you cannot use black water…?

20 Feb Posted by in Recycle | 2 comments

Question by joecool123_us: When talking about small scale waste water recycling, I have heard that you cannot use black water…?
…to irrigate crops. Sometimes, they even say you can’t use greywater to water your crops either. I was wondering why this is the case. Is it that whatever is in the water gets on the plants when you are watering them using traditional methods, or is it that the plants somehow apsorb the crud that’s in the waste water and then it’s inside of the plants.

Best answer:

Answer by Permaculture byderule
If it was straight onto the food production it can transmit diseases or parasites etc.and contaminates the produce

But not if it was filtered ,
in the Permaculture designer Manual you will find detailed drawings on how to build sewage (black water filters ,

From another tank

the water goes in a pipe coming in from the bottom of a small dam or large container pushing its way up through ,stones ,then gravel followed by sand ,
aquatic plants on the top complete the filter (to remove metals).

Black water irrigation

How ever black water straight contains to many organisms to be ever safe
like they do around Mexico city
I once stayed in a village which got their vegetables from this agriculture .
the people washed their potatoes in detergent ,ridiculous (potatoes are absorbent )
and more than half of the village was sick with stomach complaints ,(according to the doctors)

So that is not a recommendation ,
In China they use what is called night soil ,
human excrement straight on top of the lands
the place stinks and many people get sick.

Excrement has to be filtered and go through a composting process before it is safe to grow food .

In our garden the sewage goes into a double tank ,separated by a wall with a connecting opening at the bottom,the poop floats and remains in the first tank where it decomposes that over flows into a french drain (covered ditch filled with stones)which acts like an absorbent filter ,one can safely plant fruit trees on top .

what is even enough for the sewage is a long french drain with some parts that have no rocks ,
but with islands of bricks (for the worms to escape the water )and the worms will take care of the poop
again fruit trees can be planted on top

Grey water from a normal house hold should be separated from the sewage waters (to make that less)
And can go straight out of the wall into the garden
I have grown beautiful healthy tomatoes on my laundry water
and that had detergent
the shower water and the hand basins is much less harm full.
this will make the plumbing simpler and cheaper

For the kitchen use a grease trap
a little cement box with a filter and an over flow ,
because it is ugly and can start to smell if a lot goes out

check Permaculture;_ylt=AijSFyvYcEMzbvWiMNiFTdXsy6IX?qid=20070621234541AAcarVJ

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  • thor says:

    A friend bought a house and didn’t realize the outflow to the septic tank ran directly to the garden. He wondered why the corn grew so well in one area. Maybe it was just luck that he never got sick, or maybe its propaganda put out because there would be massive lawsuits if a few people out of hundreds of millions got sick.

  • Attorney says:

    I agree with the other answer in many ways..In short, black water/grey water.. may contain hazardous, toxic or biologically active substances that may contaminate food and make it unedible.. Remember last years Spinach Scare??? e. coli is a major biological contaimant in black water killed several people! If I remember correctly it was caused by black water that got into irrigation in the spinach fields from livestock..

    However, in certain instances Black and grey water can be used to irrigate crops when applied with proper procedures. CAFOs (confined animal feeding operations, e.g., pig farms and dairy farms) do it all of the time.. they inject black water from their operations into the irrigate farm fields and lessen the need for fertilizer. However, it must be done in amounts so that it gets absorbed and does not run off into drains that can pollute surface water.

    Also think about your own residential septic system (if you live outside of a city in an area not served by a sewer system)… the water gets absorbed back into the ground.. it is cleaned by both natural filtration and biological activity.. I know several residential septic fields where grass grows green all year long.. over the top..

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