rain water ?
- Thread starter knap_123
- Start date
disc1
-RT * ln(k)
rain water picks up a lot of dissolved gasses to start with. Ever hear of acid rain? Generally there can be a lot of things in rainwater that you don't want accumulating in your tank. It really isn't as pure as you'd like to think it is.
I'm really not sure what you think boiling it would accomplish.
I'm really not sure what you think boiling it would accomplish.
Fishbulb2
New member
I had this thought too but why not just skip the RO part and just aerate it to remove dissolved gases, then run it through a sediment, carbon, and DI filter. I would imagine the DI resin would last a long time since it should be low in TDS right?
Has anyone ever heard of this or tried it?
FB
one clownfish
Member
We just got some rain this morning here in Michigan. I had a cooler outside that was open and I just checked the TDS. To my surprise the rain water here is 019 ppm TDS. The water coming from the tap is 116 ppm TDS.
Mr. Fish
New member
Fishbulb2
New member
I agree with the neutral things like smog but that's why I thought a sediment, to carbon, to DI would be a good solution. It might be hard to test when the carbon block would be expired though since you wouldn't be measuring for chlorine in such a set up.
Regardless I guess, if the TDS of the rain is actually 19 ppm, it would go through DI resin really fast and you'd have to use RO. At that point, you might as well start with tap water. I am also surprised that the rain water TDS is so high. I wonder how much came from the cooler itself. If you really want to do this seriously, I think you would want to catch the water from your roof gutters in something like a rain barrel to get enough of it to be worth it. At that point, I can easily imagine that water coming off of the roof would be filthy. As you can tell, I've thought about this a lot, but it just seems impractical.
If you want to save some water, you could try a rain barrel and just use that to water a flower garden or lawn for example.
FB
BigAl2007
Active member
Even though it sounds like a good (and GREEN) idea I highly suggest you not use rainwater. Even in one of the most pristine places on the planet the "Rain" is heavily polluted here in the Blue Ridge Mountains. The rain isn't polluted from what we do to it locally but what happens in other areas of the country and the world even.
If you doubt what effect it has check out some of these fairly recent pictures of the pines here in the BRM
Here is a brief exert from a local website about Grandfather Mountain here in North Carolina
If you doubt what effect it has check out some of these fairly recent pictures of the pines here in the BRM
Here is a brief exert from a local website about Grandfather Mountain here in North Carolina
MCsaxmaster
New member
Rainwater TDS is very low (i.e., the water if very soft) yet will tend to have a lot of nasties in it which you don't want to introduce into your tank. This is an ideal example IMHO of where folks can easily misunderstand what the TDS is telling us.
Simply put, we don't care what the TDS of the water we use in our tanks is--we care whether or not there are undesirable substances like ammonia, phosphate, chloramine, heavy metals, etc. in that water. There's no reason to worry about something like small amounts dissolved NaCl in the water or dissolved CaCO3--those are totally harmless. TDS does not distinguish between harmful dissolved substances and harmless dissolved substances--it is just a measure ot the total (electrically charged) dissolved substances. In practice we try to get close to zero TDS because if we get very low TDS this typically means that we have removed most of the nasty substances that we want to get rid of. If the TDS is well over zero it doesn't mean the water is inherently unsafe, it means that there is *something* dissolved in it, and in practice some of this will be nasty stuff we want to avoid.
In the case of rain water we have very little dissolved stuff, but the stuff that is there can be nasty stuff that we don't want to introduce. Low TDS is no guarantee that the water is sufficiently pure and high TDS is no guarantee that the water has anything harmful in it--it's simply a question of pragmatism, so we aim for very low TDS when using municipal water sources.
cj
Simply put, we don't care what the TDS of the water we use in our tanks is--we care whether or not there are undesirable substances like ammonia, phosphate, chloramine, heavy metals, etc. in that water. There's no reason to worry about something like small amounts dissolved NaCl in the water or dissolved CaCO3--those are totally harmless. TDS does not distinguish between harmful dissolved substances and harmless dissolved substances--it is just a measure ot the total (electrically charged) dissolved substances. In practice we try to get close to zero TDS because if we get very low TDS this typically means that we have removed most of the nasty substances that we want to get rid of. If the TDS is well over zero it doesn't mean the water is inherently unsafe, it means that there is *something* dissolved in it, and in practice some of this will be nasty stuff we want to avoid.
In the case of rain water we have very little dissolved stuff, but the stuff that is there can be nasty stuff that we don't want to introduce. Low TDS is no guarantee that the water is sufficiently pure and high TDS is no guarantee that the water has anything harmful in it--it's simply a question of pragmatism, so we aim for very low TDS when using municipal water sources.
cj
Fishbulb2
New member
Well, it's not about misunderstanding TDS. It's just that DI resin does not discriminate. So if you want to use DI resin to remove say phosphate, ammonium, nitrates, or other nasties, you will still burn through DI resin removing NaCl, Ca, and any other harmless ions. I don't think anyone here suggested the quality of water has anything to do with TDS (I've posted hundreds of times on just that issue). But if you want to use something like DI resin or a Kati-Ani system to filter water, you WILL want to know what your incoming TDS is like.
FB
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