does rain water need to go through a filtration process?

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karenb's picture
karenb
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does rain water need to go through a filtration process?

Can anyone tell me if rain water needs to go through a filtration process? Do all water filters do the same thing by taking impuritites from the water?

 

thanks.

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Ken C
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Re: does rain water need to go through a filtration process?
karenb wrote:

Can anyone tell me if rain water needs to go through a filtration process? Do all water filters do the same thing by taking impuritites from the water?

 

thanks.

 

Karen,

You may wish to read this forum thread on water.

http://www.peakprosperity.com/forum/definitive-water-thread/17225

 

It will probably answer many of your questions.

Ken

 

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Rector
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Re: does rain water need to go through a filtration process?

Karen,

On a once in awhile basis, you can get away with drinking rainwater that is unfiltered because it is basically distilled water with very few microorganisms that will cause water borne illness.  Your capture device and storage method may be less than perfect however, so I would filter or purify if it has sat around for long.

Depending on atmospheric conditions, the rainwater may also pick up dust particles from the air and end up kind of gritty, or worse it could pick up pollutants (acid rain) in the atmosphere.  

When I was in the Army, we collected and drank rainwater and we used purification tablets after letting it settle.  It always had a twang to it, and I have no idea why.  None of us died however so. . .

FWIW,

Rector

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Re: does rain water need to go through a filtration process?

If you capture rainwater cleanly, then you can drink it straight and many communities the world over do this quite regualrly.

However if your catchment system is your roof and birds have a habit of landing on your roof and depositing fecal matter there, then you're going to want to filter the water.

The more elegant rainwater catchment systems from roofs include a "first run" excluder which dumps the first x-number of gallons during a rainstorm depending on the size of the roof, the system, and the level of safety/purity desired.  They are nothing more complicated than a pipe that first must be filled before it overflows into your rain cistern(s), the volume of the pipe being your "x-gallons" that get tossed.  The pipe has a small hole in the bottom so the first-run water weeps away to ready the pipe for the next use.

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Dogs_In_A_Pile
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Re: does rain water need to go through a filtration process?
karenb wrote:

Can anyone tell me if rain water needs to go through a filtration process? Do all water filters do the same thing by taking impuritites from the water?

 

thanks.

Karen -

Just to add to what the others have provided, not all purification systems do the same thing.  Some provide mechanical filtration only, others do both mechanical and bacterial filtration.  If you go with a collection/filter system that only does mechanical filtration you will need to treat the water afterwards to eliminate bacterial concerns.

There are any number of great systems out there that do both.  We have a large capacity system that has mechanical filtration that is also passed through a silver impregnated, activated carbon core for bacterial treatment.  I have several portable system options I use hiking the Appalachian Trail that also do both. 

Full disclosure:  I use Katadyn products - specifically the Hiker Pro series - they are reliable, durable and very lightweight.  MSR also has a great product line.  If there is better stuff out there I will probably get it, I just haven't found anything yet.

If you do go with one of these systems, make sure you get a bunch of spare filter elements.  Depending on the contamination levels of the water source, the useful filter life will vary.  I routinely get 400-600 gallons of water out of my Katadyn filter before I feel the need to replace it (probably conservative) - and that is to support casual hiking and use.  In a pinch I would not hesitate to push it a little further if I was reasonably satisfied with the relative integrity of my source water (cool mountain stream vs. the neighborhood borrow pit pond or lake). 

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GiraffeOK
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Re: does rain water need to go through a filtration process?

Does rainwater used for purposes other than human consumption need to be filtered in some way, and if so, what is a practical way to do it? For example, bathing, or watering livestock.

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james_knight_chaucer
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Re: does rain water need to go through a filtration process?

Chris,

I was thinking about this the other day from the point of view of lead poisoning. We are nowadays encouraged to do away with lead supply pipes. Here in the UK most roofs are flashed with lead. I am happy to use water from my rooftop to water the garden, but I would have to be very thirsty to drink it.

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Damnthematrix
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Re: does rain water need to go through a filtration process?
cmartenson wrote:

If you capture rainwater cleanly, then you can drink it straight and many communities the world over do this quite regualrly.

However if your catchment system is your roof and birds have a habit of landing on your roof and depositing fecal matter there, then you're going to want to filter the water.

The more elegant rainwater catchment systems from roofs include a "first run" excluder which dumps the first x-number of gallons during a rainstorm depending on the size of the roof, the system, and the level of safety/purity desired.  They are nothing more complicated than a pipe that first must be filled before it overflows into your rain cistern(s), the volume of the pipe being your "x-gallons" that get tossed.  The pipe has a small hole in the bottom so the first-run water weeps away to ready the pipe for the next use.

We have first flush systems in place here.... but we still filter the water we drink at the kitchen tap.  It's the only tap we filter.  After about three years, she who must be obeyed started complaining the water tasted "funny".  I still thought it tasted way better than town water, but I relented and fitted the filtering system I used to use in my darkroom, another life ago.

This uses two elements in series, a fine filter to take out the rocks, and an Activated Carbon element that, my son who has a biology degree tells me, removes bacteria and even most viruses......  The water does indeed taste a lot better....  and we never get sick from drinking it.  In fact, if we ever have to go some distance or for some time away from the farm, we take our own water with us, because frankly, town water is just disgusting stuff to drink!!

Mike

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NZSailor
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Re: does rain water need to go through a filtration process?

We've been living with roof water catchment for ten years now on our farm in New Zealand. We store all the water that falls on our house, garage, guest cottage and sheep shed in large (10,000 gallon) buried or partially buried concrete tanks.

We don't have a first flush system (though we should) but before the water enters the house it passes through a 20 micron cartridge filter, then a 1 micron spun filter and finally through an ultraviolet filter (bright light) to kill the bugs.  That filters the water for the entire house- showers, toilets, sinks etc. 

Our fridge has an icemaker and water available in the door and we have put an additional carbon filter just behind the fridge so our drinking water and ice has one more level of filtration.  We change the filters every 12-18 months and the bulb in the UV filter every two years.  The UV bulb runs continuously but doesn't use much power.

Coming from the US I was a bit nervous about roof water but as Mike says it does taste better than the local town water and we've never gotten sick from it.  We need to improve our system a bit with the first flush systems etc. but it has worked very well for us.

Chip

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