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There has to be some kind of membrane that removes salt. Does an RO filter remove salt?
RO does remove salt, its membrane will remove just about everthing, the battery manufacturers even said it is pure enough for battery water. I have one that makes water for my off-grid batteries.
Some of the largest fresh water plants, in the Middle east, use RO to make fresh water from sea water. Desalination - Wikipedia, the free encyclopedia Californis will be building some soon Dry California OKs huge desalination plant - Environment- msnbc.com
 

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Hi,
Really its a nice idea to make water filter. Definitely I will try my best to build a water filter for me. A water filter provides clean, healthy water for cooking, as well as drinking, at the convenience of tap water. Also Water filters provide better tasting and better smelling drinking water by removing chlorine and bacterial contaminants. you can also buy good quality of water filter from market with an affordable price.


Thanks.
 

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I have built my own, made from sealable food-grade plastic containers connected 'in-series' with clear vinyl/plastic tubing, [in-flow from top in to, out-flow out the bottom of each filter container], aquarium supplies are great for buying filter media. Most fish are extremely sensitive to irregularities in their water, they sell; superfine media bags, activated charcoal, also resin matrix 'chemical scrubbers' which remove harmful chemicals/metals, suspended in the water. Start with a 'pre-filter' to separate all the particulate you can see, [I use a stainless steel drain basket with a large commercial-size paper/fiber coffee maker filter], these are available at restaurant supply stores. My filter containers have holes drilled for the in-flow & out-flow hoses, sealed with clear silicone bathtub caulking, the lids all lock down with silicone gaskets for sealing. On the first in-series container, I have mounted an air fitting compatible with a small hand-held bicycle pump in order to pressurize the containers to get the water flowing form one filter container to the next in line. Everything fits inside a 'RUBBERMAID ROUGHNECK' 18gallon storage container, making it completely portable. I finish my water with my SteriPEN, just to be safe.
 

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A friend just gave me this link to making a bio-sand filter that is commonly used in third world countries to clean water.
Bio-sand filter
You do have to download the file but it has pictures and is really worth giving a good look. Most parts that are used are easily available now and it might be worth getting the parts to make one now and just have it available. It is something that the hubby and I have talked about and thought about getting all the parts and the Rubbermaid tub and just store it till needed.
 

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howdy yall, i like this subject. im planning on building a biosand/slowsand filter. ive done quite a bit of research and aside from berkey and sawyer, which are not very cheap, not unaffordable, but not cheap, the biosand is my personal choice for purification. and its realitively affordable as well as not too difficult to make. it takes some time to get going, but once the beneficial bacteria get established in the very top layer of the sand it is supposed to filter out most if not all voc's (volitile organic compounds). please do your own research and dont take what im saying as absolute truth, i am by no means an expert. i just studied untill i was satisfied as to which rout i would follow. just my 2 pennies. good luck and be safe!
 

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howdy yall, i like this subject. im planning on building a biosand/slowsand filter. ive done quite a bit of research and aside from berkey and sawyer, which are not very cheap, not unaffordable, but not cheap, the biosand is my personal choice for purification. and its realitively affordable as well as not too difficult to make. it takes some time to get going, but once the beneficial bacteria get established in the very top layer of the sand it is supposed to filter out most if not all voc's (volitile organic compounds). please do your own research and dont take what im saying as absolute truth, i am by no means an expert. i just studied untill i was satisfied as to which rout i would follow. just my 2 pennies. good luck and be safe!
VOC's are an interesting group of contaminants and include some pretty nasty ones. They vaporize at a low temperature and usually give off a strong odor. They can give water a sweet taste, too. They include gasoline, benzene, paints and solvents. If you have any VOC's in your water source, you will want to use activated carbon to remove it. Granulated Activated Carbon will reduce the VOC's as well.

As far as Berkey's and Sawyer products, Berkey's do remove VOC's. I don't believe Sawyer claims to remove them. I've seen others claim they do, but Sawyer doesn't state this on their website.
 

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Bio-sand filter
You do have to download the file but it has pictures and is really worth giving a good look.
If anyone can not download this, please PM me with your email address and I will attach it to an email for you. It is less than 1Mb

Most parts that are used are easily available now and it might be worth getting the parts to make one now and just have it available.
Absolutely. I have enough "parts" to make three... but not enough sand. Sand is easy to find but hard to move. I don't have a lot of room to store spare sand right now. Maybe I can make a HUGE sandbox for the kids? That will be my reserve!
 

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is this possible and how can I make a filter like this using sand and random junk?
It is possible, but depending on scale all you are making is a strainer.

DIY filters are very possible and can be done on the cheap, but first ask your self what this filter is for? Do you want the knowledge to survive a "stranded in the middle of nowhere" situation by yourself, or are you seeking the info for a long-term water solution for a family of 6.

The Bio-Sand type of filter has some great qualities as well as some draw backs. In a "survival" situation, the materials are probably lying around for you to build one, but you have to remember the causes of surface water contamination, most of them come from run off over the sand and gravel you are going to use to make the filter.

Planing for a long-term situation, hopefully prior to the situation :gaah: , gives you some time to do your research and find some decent quality materials to make a first rate filter. It also gives you the ability to improve on the Bio-Sand filter by adding two additional types of filtering media, Activated Charcoal and Dichotomous Earth. Those additions take the Bio-Sand filter up a notch or two.

The big draw back after you get over the "quality" of filtering media being used with the Bio-Sand is that you have to keep it running in order for the "Bio" portion of the filter to work (much like the Bio-Wheel fish tank filter). Once it drys out and the "Bio" dies off, it will take a fair amount of use to reactivate the bio function. The "Improved Bio-sand" design that keeps the filtering media wet by raising the exit point for the filtered water works, but not on an extreme long term situation, because just like any standing water, it will get nasty.

If you add a layer of Activated Charcoal (for flavor) followed by a layer of Dichotomous Earth (for critters) as the last 2 layers, you will drastically improve the effectiveness of your filter, and it will work even if you just dragged it out of the closet for the first time, or if you have run it daily for months.

A Building Supply company that caters to Mason's will have the sand and Pea Gravel you need. Fine Sand aka "Mason's sand" and Coarse Sand aka "Torpedo" or "Play sand". The reason you go to a place like this rather than buy a bag of sand is simple, when you walk in to the office and ask to fill a couple of buckets of sand, they usually let you go for free. They sell the stuff by the ton, not by the pound, and their scales are usually in 20lb increments.

When you decide on a container to hold your media, consider length as being more important than diameter. A five gallon bucket with say 15 lbs of media properly layered will filter less contamination and critters out than a 4" diameter pipe that is long enough to hold the same 15 lbs of properly layered media.

Will this filter out chemicals and salt? Don't count on it, but it will get out the beasties that will make you very sick and most of the chemicals. The Bio-Sand Filter on it's own is not that remarkable, it only reduces water caused diarrhea by 50% ish, but it certainly is a good start.

Here is a good video.... I would add the layers of Activated Charcoal and Dichotomous Earth between the Pea gravel and sand using an extra end cap with holes drilled like the "diffuser plate" and then a coffee filter on top of that to prevent the finer Dichotomous Earth to infiltrate the pea gravel.


The Big Berkey is nice but pricey, but you can duplicate it for much less using the same filters in a DIY bucket set up.

DIY Berkey Filter
 

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.I would add the layers of Activated Charcoal and Dichotomous Earth between the Pea gravel and sand using an extra end cap with holes drilled like the "diffuser plate" and then a coffee filter on top of that to prevent the finer Dichotomous Earth to infiltrate the pea gravel.
I would avoid doing that.... keep it simple (KISS principle)

The final product that comes out can have the last few (if any) pathogens killed with a little bleach. You can pour the water back and forth between two buckets to get the bleach out.

Nothing takes salt out, except for distillation.
 

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I would avoid doing that.... keep it simple (KISS principle)

The final product that comes out can have the last few (if any) pathogens killed with a little bleach. You can pour the water back and forth between two buckets to get the bleach out.

Nothing takes salt out, except for distillation.
Can't disagree with the KISS concept! But that is why I would add those two items to the filter.

1st it makes it ready to use right off the bat and you do not have to wait until the Bio Flora is developed in order to consider the water safe to drink, and you do not have to maintain that Bio Flora through regular use.

2nd, adding a second step using bleach while simple, does add more steps to the process.

It all boils down to the situation at hand and whether or not you have the time and materials to get it done. If you are improvising this filter Post SHTF you may not have any options in filtering media, but in the good times, there is no reason not to improve on an idea.
 

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I was a water engineer in a previous life. I wouldn't advise it because you have no way of knowing its working except the hard way.

The only way is to invest in a proper Bio system. without a lab you do not know what is in the water. Sand etc may filter out solids but why bother, you can buy a 5 micron water filter for about 5 dollars. But it won't filter out the bacteria and viruses, neither will charcoal

Its the biological contamination you need to fear and there are things out there that could definitely kill you if sewage gets into the water supply.Even if it doesn't kill you directly it will be horrible and render you so debilitated you will most likely die of the side effects.

But you probably only have one source of water so you cannot take chances. The only way to be sure about water is to boil it and thats a good 10-15 minute hard boiling. Buy a woodburning kettle.

It depends where you are, if you are halfway up a mountain you should be reasonably safe. In general though I don't think the risk is worth it.
 

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24 hours after previous post

There is a thing called the Ribena test. Ribena is a blackcurrent cordial sold in britain . Mix up a quart then put it through the filter. Chances are it comes through blackcurrent colour and blackcurrent flavour.

Then substitute the word Ribena for the word Poop and you start to see the problem
 

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There is no need to shoot the wounded.

First, the blackberry currant isn't a good test, because a biosand filter needs a few weeks to build the "Schmutzdecke" http://en.wikipedia.org/wiki/Schmutzdecke

Doing that would kill the Schmutzdecke, making the filter useless.

You can kill the poop "fecal coliforms" by bleaching the water several days before needing it and letting the chlorine evaporate out (so it also does not kill the Schmutzdecke)

This should supply you with sterile and clean water, which can then be run through activated carbon to remove any petrochemicals.
 

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I should also add that there should be multiple ways for you to clean your water. A Berkey is a GREAT tool... but please don't dump swamp water into it, even though you could. Feed it with the cleanest water you can, so the filter "candles" stay cleaner for a longer period of time.

The BioSand is a great tool to get you to the point where the water is pretty good quality. You can add a little bleach afterward to kill pathogens, then aerate for a while to let the chlorine gas out. You could even run this water through a PUR or BRITA filter before the Berkey if you wish, but there are many ways to clean your water properly.
 
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