<p>I think everyone would agree that distilled water is clean fresh water, but it wouldn't be practical to supply a large population with a water supply made up entirely of distilled water. Good water desalination devices using semi-permeable membranes have been invented and are used in some drought stricken countries. They can filter out things as small as sodium and chlorine ions, so produce very high quality water, but it tends to be expensive. When you are talking about a water supply for millions of people, these expensive purification methods are not practical for everyday purposes.</p>

<p>The basis of a mass supply of clean, fresh water suitable for drinking is filtration, so water from reservoirs is run through filtration beds of sand to remove particulate matter and most micro-organisms. It then has to be sterilised, which is done with chlorine. The result is a product which although containing a number of impurities in trace amounts (chlorine, calcium, iron etc) which are not harmful, fulfils the scientific definition of clean, fresh water suitable for drinking. Water from deep boreholes is also suitable despite trace amounts of mineral impurities, and is free of harmful micro-organisms so needs no sterilisation. Shallower wells and boreholes may be contaminated by pathogenic microbes, so the water sometimes needs sterilisation. </p>

CC BY-SA 4.0
2019-06-27T09:24:40.413Z
2019-06-27T09:24:40.413Z
Michael Walsby
<p>Honestly I think nobody's invented a good water desalination device because nobody knows the scientific definition of clean drinking water.</p>

<p>So scientifically, what is the definition of clean fresh water?</p>

CC BY-SA 4.0
2019-06-27T08:23:34.703Z
Fresh water *for what purpose*?
Jan Doggen
CC BY-SA 4.0
2019-06-27T18:35:48.237Z
I dispute the idea that nobody has invented a good water desalination device. Hundreds of thousands of people live off desalinated water. I also dispute the idea that nobody knows a scientific definition of "clean fresh water" - for example, every government and public water authority will have a definition of this. Some other people who use water will also have definitions of this, and *they will probably be different*.
Semidiurnal Simon
CC BY-SA 4.0
2019-06-28T00:17:05.923Z
Also I think the question as is phrased at the moment is a bit nonsensical. There have been quite a few inventions in the history of mankind without much theory behind it.
AtmosphericPrisonEscape
CC BY-SA 4.0
2019-06-28T04:43:42.443Z
I don't think there is a definition for fresh water, but there is for potable water
Fred
CC BY-SA 4.0
2019-06-28T13:16:11.340Z
@Fred Yes there is. Fresh water is water with less than 1% dissolved salts, that's it. It just does not define whether it is drinkable or not. potable water is not the same as fresh water, you can even have potable water that is not fresh.
John
CC BY-SA 4.0
2019-06-28T15:13:01.300Z
Sorry folks, you've all made me realize I should have defined my question differently.
leeand00
CC BY-SA 4.0
2019-06-28T18:46:21.150Z
@leeand00 you can edit it! And I encourage you to do so. Look for an "edit" button just under the question. EDIT: Sorry, just realised that while you're new here you're not new to stackexchange. So you know this ;-) If you know how to make the question better, then please do!
Semidiurnal Simon
CC BY-SA 4.0
2019-06-28T18:49:47.383Z
@SemidiurnalSimon Yeah I’m quite out of my depth here, while I know where the edit button is, I know nothing at all about water.
leeand00
CC BY-SA 4.0
2019-06-28T18:53:34.153Z
@leeand00 *grin* fair enough. If you can put your finger clearly on exactly what you want to know, then you'll find this community usually loves an interesting question that isn't "what type of rock is this" ;-)
Semidiurnal Simon
<water>
How does one scientifically define drinkable water?
leeand00
# How does one scientifically define drinkable water?

(Asked by: username_0 on 2019-06-27)

Honestly I think nobody's invented a good water desalination device because nobody knows the scientific definition of clean drinking water.

So scientifically, what is the definition of clean fresh water?

**Tags:** water

> **Comments:**
> **username_1**: Fresh water *for what purpose*?  
> **username_2**: I dispute the idea that nobody has invented a good water desalination device. Hundreds of thousands of people live off desalinated water. I also dispute the idea that nobody knows a scientific definition of "clean fresh water" - for example, every government and public water authority will have a definition of this. Some other people who use water will also have definitions of this, and *they will probably be different*.  
> **username_3**: Also I think the question as is phrased at the moment is a bit nonsensical. There have been quite a few inventions in the history of mankind without much theory behind it.  
> **username_4**: I don't think there is a definition for fresh water, but there is for potable water  
> **username_5**: @username_4 Yes there is. Fresh water is water with less than 1% dissolved salts, that's it. It just does not define whether it is drinkable or not. potable water is not the same as fresh water, you can even have potable water that is not fresh.  
> **username_0**: Sorry folks, you've all made me realize I should have defined my question differently.  
> **username_2**: @username_0 you can edit it! And I encourage you to do so. Look for an "edit" button just under the question. EDIT: Sorry, just realised that while you're new here you're not new to stackexchange. So you know this ;-) If you know how to make the question better, then please do!  
> **username_0**: @username_2 Yeah I’m quite out of my depth here, while I know where the edit button is, I know nothing at all about water.  
> **username_2**: @username_0 *grin* fair enough. If you can put your finger clearly on exactly what you want to know, then you'll find this community usually loves an interesting question that isn't "what type of rock is this" ;-)  

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## 1 answers

### Answer by username_6 on 2019-06-27. Score: 2

I think everyone would agree that distilled water is clean fresh water, but it wouldn't be practical to supply a large population with a water supply made up entirely of distilled water. Good water desalination devices using semi-permeable membranes have been invented and are used in some drought stricken countries. They can filter out things as small as sodium and chlorine ions, so produce very high quality water, but it tends to be expensive. When you are talking about a water supply for millions of people, these expensive purification methods are not practical for everyday purposes.

The basis of a mass supply of clean, fresh water suitable for drinking is filtration, so water from reservoirs is run through filtration beds of sand to remove particulate matter and most micro-organisms. It then has to be sterilised, which is done with chlorine. The result is a product which although containing a number of impurities in trace amounts (chlorine, calcium, iron etc) which are not harmful, fulfils the scientific definition of clean, fresh water suitable for drinking. Water from deep boreholes is also suitable despite trace amounts of mineral impurities, and is free of harmful micro-organisms so needs no sterilisation. Shallower wells and boreholes may be contaminated by pathogenic microbes, so the water sometimes needs sterilisation.


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