Drinking water harvesting

Now that all is said and done and the water bio-sand filter is filtering away successfully, I thought it would be a good thing to share the things I would do differently next time – a real bonus for any of you starting out, as it means you can get it right first time!

The water results

I sent my water into Water Guru (www.waterguru.co.za) for testing after the three weeks of initial filtering without drinking. Here are the results of the tests done:

Determinants Constituents

Target Limits

Results

ALKALINITY

20-200 MG/L

25

AMMONIA MR

0-1.0 MG/L

0,16

CALCIUM

10-200 MG/L

20

COLOR OF WATER

<15-<30 MG/L

10

COLIFORMS/E.COLI

0(35degrees)

0

FLUORIDE

<50 MG/L

0

HARDNESS

20-220 MG/L

36

HARDNESS CALCIUM

20-200 MG/L

152

HARDNESS MAGNESIUM

 20-200 MG/L

93

IRON HR

0.3 MG/L

0

MANGANESE

<50 (Target <10) MG/L

0

NITRATE HR

<10 (Target <5.0) MG/L

4

PH

6.5 - 8.5 PH

7,52

SILICA

10 MG/L

6,7

SULFATE

<250 MG/L

10

TDS

20-500 TDS

51

So, at a glance you can see that the results came in way within the acceptable levels and the water tastes so much better than from the municipal source with a coal filter. Plus, when we boil the water in the kettle, there is no smell of chlorine.

What I would have done differently

Drum size

Way too big, just about all the bio-sand water filters I have seen and researched used a much narrower container – best solution being a cement container.

A manual on how to make a cement bio-sand filter - https://cdn.instructables.com/ORIG/FI6/HI2J/I6C2MP0W/FI6HI2JI6C2MP0W.pdf

The height seems to be fine, but the wide drum makes for too much sand and stone to be prepared.

The upside though I would guess is that it does a better job of the filtration.

Ball valve on storage drum

If you have a ball stop valve on the storage drum side, you don’t have to control the water at the tap of the non-filtered JoJo storage side. Water would flow until a certain level in the storage drum is reached, stopping the flow from the Bio-Sand and stopping the inlet from the JoJo.

Un-filtered water storage

The JoJo to store water from our Zinc-a-lum awning, is too small at 750l, because of the lack of rain of late, this should be around 2500l.

Un-filtered JoJo level

Our bio-filter drum and un-filtered storage JoJo are at the same level, which means that once the water drops below the inlet to the bio-filter, the water stops flowing – as it is a gravity feed – no rush of water needed.

If the inlet un-filtered storage tank was higher, I would be able to have the water flowing until it reached the bottom of the feed tank, and not stop a meter or so from the bottom.

Higher storage drum

The filtered storage drum should be a higher so that it is easy to reach the tap when decanting into your drinking water containers. A nice enhancement here would be connecting this storage to the household drinking water taps.

 

That is it from this series on the drinking water harvesting, we are extremely happy with our drinking water quality, especially knowing the source of the water and having the water pass all the quality tests with such flying colours.

Other related articles in this series:

  1. Harvesting Drinking Water - Preparation
  2. Sorting and Cleaning the Sand
  3. Making the bio-sand filter drum
  4. Lessons Learnt
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