This is the fourth instalment in a five-part series called Fluid Waste Management & Septic Tanks. To read the rest, click here.

On a water scarce continent such as Africa there is fast approaching a time when water will become the scarcest of commodities. Commentators are already foreseeing that the next great conflict will be fought over water.

It makes no sense, therefore, for the current generation of homeowners to be wasting the stuff.

And these wasteful ways include:

  • Washing motor cars, paving and driveways with municipally-treated drinking water,
  • Watering lawns and gardens with, likewise, municipally-treated drinking water, and,
  • Flushing toilets with municipally-treated drinking water.

For all of these activities, filtered fluid waste is eminently suitable. It can drastically reduce a household’s water bill (if it pays for municipal water) or new water use (if it relies on a borehole or well).

Grey Water and Black Water

Knowing that domestic fluid waste has two components, namely grey water and black (toilet) water is the starting point.

By separating the two, and treating them differently, one can radically reduce one’s wastage. In reality, the proportion of grey water in a household’s waste far exceeds the black water.

And even if one is connected to a municipal sewerage system it is not beyond the capabilities of a handy D-I-Yer to replumb the house’s basin, sink, shower and bath outlet pipes into a grey water reticulation system.

A simple sand filter.

But here’s the fact: Many so-called experts say it is acceptable to simply use “raw” grey water for irrigation in the garden, vegetable patch etc. It is not, for the following reasons:

  • Raw grey water contains significant contaminants and solids (eg food scraps, human hair, soil from washing vegetables etc) which will decompose and smell.
  • This same kind of water contains “fogs”. These are fats, oils and greases that, even if one carefully wipes plates, pans etc before washing will, in time, result in the soil becoming “sealed” and impervious to water penetration.
  • Raw grey water contains traces of drugs and other chemicals, as well as bacteria, that can be harmful to plant and insect life.

How can we filter waste water?

Besides, if one has the skills to replumb the house, one has the skills to build a simple gravel and sand filter for the harvested water that will clear it of impurities and solids.

If you convert your household to such a dual system you will certainly generate enough clean, non-potable water for toilet-flushing and some garden use, but by no means all. The saving in new water use will definitely be noticeable in your water bill.

But you will be more than halving the volume of your waste into either your septic system or the municipal line.

For Part Five, click here.

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