Silver has been recognised for it's natural antibacterial properties for thousands of years. It was common to store water in silver containers, or just add silver and copper coins to water or milk to keep it fresh.
More interestingly, silver has been used as a medicine since long before the modern pharmaceutical industries existed, and can even kill strains of bacteria that are resistant to modern antibiotics. This project is about making a drinkable form of silver by electrically diffusing silver ions into water.
If this sounds rather technical, then you'll be surprised to know that it simply involves passing a dc current between two silver electrodes.
There is no known overdose limit for colloidal silver, although extremely strong concentrations and more particularly silver based pastes can cause a condition known as aggria. This is where the silver causes a permanent blue discolouration of the skin. It takes absolutely huge quantities of ingested silver to do this, and since colloidal silver is usually taken at low concentrations, it is not really a cause for concern. Given the relative rarity of aggria it may even just affect people who have a biological trait that causes the silver to accumulate at the surface of the skin.
I drank a glass of this colloidal silver daily for months with no adverse effect. That said, I didn't particularly notice any beneficial effect either. Probably because I'm relatively fit.
Here's an interesting link to someone who suffered from aggria and clearly doesn't care for the consumption of colloidal silver.
Anti silver site.
Even if you don't want to drink it, the silver loaded water can be used to soak things like dressings or socks for the antibacterial properties.
Note that this type of electrolytically produced silver water is sometimes called ionic silver.

Here are the components required.
A small plastic project case with a built in PP3 battery holder and a battery clip.
A couple of standard 4mm banana plugs as used on most test equipment.
A couple of matching sockets (one red and one black if desired).
An LED to indicate current flow, this should be a super high sensitivity LED like the modern Gallium Nitride green ones which will glow brightly at just a hundred micro-amps.
A resistor chosen to pass the desired current. In this case I used a 10K resistor for less than 1mA, but you could use a 1K resistor for closer to 10mA if you like.
And the most crucial bit, 3mm diameter fine silver electrodes. The word "fine" defines that the silver is of extremely high purity and doesn't contain other metals like Sterling silver does.
You should be able to get the silver at your local jewellery suppliers or bullion merchants, and while it is fairly expensive, it will last a long time.

First put a bit of masking tape on the base of the case to ease marking and drilling, then drill two holes for the electrode sockets (as shown above) and a 3mm hole for the LED in the middle of the front of the case.

Wire the guts as follows... The black battery lead goes to the negative electrode socket and the red battery lead goes to the anode of the LED.
The cathode of the LED (short lead) is connected to the resistor which is then connected to the positive electrode socket. This means that any current passing between the electrodes will cause the LED to glow while being limited by the resistor.
You may wish to file the tip of the LED flat without going too deep and damaging it's internal metalwork. This will improve the viewing angle. I've also used a small cable tie to secure the battery leads to the negative electrode socket to protect them from being pulled.
There's no switch because the unit only passes current if the electrodes are submerged in liquid. (Or laid on a conductive surface!)

Two pieces of the silver are cut to a length dictated by the depth of the glass tumbler this unit will be used with later. I cut mine at three inches (75mm).
Each piece of silver (a silver electrode) is then soldered into a banana plug.

The covers are screwed back onto the banana plugs, and the electrodes are ready.

A battery is fitted, the electrodes are plugged in, and the unit is placed on a glass of water with the electrodes submerged.
The LED should glow and after a while, a mist of silver will be seen forming around the anode. It may help to stir the water with the electrodes occasionally to diffuse the silver.
The amount of current flowing and the resultant intensity of the LED will vary according to the purity of the water. Ordinary tap water is pretty conductive because it already has impurities and minerals in it. Ideally you should use distilled water which is virtually impurity free, but doesn't conduct too well. In this case it may be better to design a system that operates at a much higher voltage.

As the trace quantities of silver merge into the water, it will become more and more conductive.

Since only a very small percentage of silver (measured in parts per billion!) is required for it's anti bacterial effects, you can usually drink the solution after about 15 minutes with ordinary tap water.
As the unit is used, a film builds up on the electrodes, and every so often it will be necessary to clean them by gently wiping them with either your fingers, or a soft nylon scouring pad.

Here's the unit in a hand to help get it's size into perspective. It's pretty compact.

You may want to experiment with colloidal copper too, which has similar benefits as silver, but is reputed to be especially active against algae. For this you just need to make up another pair of electrodes with copper wire instead of silver. I can't say I was impressed at the copper version since it seems to be much slower than the silver.

You can do a bit of research on the Internet, searching for colloidal silver. It's quite a controversial subject and is surrounded with a lot of quackery as people try to justify excessive prices for what I've described above.

Something else to research is a pool ioniser, since this is a device that generally releases both copper and silver into pool water as described above. These devices can greatly reduce the need for chlorine in pools, and the scientific evidence of bacterial destruction is incredible.
Has lots of interesting information. They actually manufacture units for safe pool sterilisation.
This company sells a cute solar powered unit that floats on your pool and keeps it clean and fresh. The fact it's solar powered probably means it's useless here in the UK, but then we don't have many outdoor pools because the ice tends to rip our swimming trunks. (It'd be nice for fish ponds though)
If you want to make pure colloidal silver, then you will need to use distilled water. While this is easily available in the USA, it's hard to come by in the UK and the purchase of a very expensive water distiller will be required. Personally I think that tap water is fine, particularly if the silver is being drunk immediately.
Don't just drink the colloidal silver. Try it in pools and on plants.
If you have very pure water or are using distilled water, then it may be a good idea to boost the voltage either by using three batteries in series, or a suitable mains adapter.
You can make pure water conduct better with a touch of salt, or better still, just add a bit of the last batch since the silver content improves the waters conductivity.

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