Why buy a replacement filter for $6 to $10 (or more) when you can refill your old filter cartridge housing for about 50 cents?!
Refilling is quick, easy and economical. If you can refill a salt shaker, then you should be able to refill a Brita, PuR, or other brand water pitcher cartridges. All that you will need is an old cartridge, some activated carbon, a polyethylene plug, a sharp utility knife or Xacto knife. A 1/2" drill motor and 1/2" drill bit are optional, but can aid in rounding out the hole.
Step 1: A Bit About Activated Carbon and Where to Buy Small Quantities.
Activated carbon is also known as activated charcoal and is a VERY effective substance at absorbing many unwanted contaminants in drinking water and other liquids.
The History of Activated Carbon
Activated Carbon was first known to treat water over 2000 years ago. However, it was first produced commercially at the beginning of the 20th century and was only available in powder form. Initially activated carbon was mainly used to decolorize sugar and then from 1930 for water treatment to remove taste and odor. Granular activated carbon was first developed as a consequence of WWI for gas masks and has been used subsequently for water treatment, solvent recovery and air purification. The unique structure of activated carbon produces a very large surface area: 1 lb of granular activated carbon typically provides a surface area of 125 acres (1 Kg =1,000,000 sq. m.). Activated carbon can be produced from a variety of carbonaceous raw material, the primary ones being coal, coconut shells, wood and lignite. The intrinsic properties of the activated carbon are dependent on the raw material source. The activated carbon surface is non-polar which results in an affinity for non-polar adsorbates such as organics. Adsorption is a surface phenomenom in which an adsorbate is held onto the surface of the activated carbon by Van der Waal's forces and saturation is represented by an equilibrium point. These forces are physical in nature, which means that the process is reversible (using heat, pressure, etc.) Activated carbon is also capable of chemisorption, whereby a chemical reaction occurs at the carbon interface, changing the state of the adsorbate (dechlorination is an example of a chemisorption process). (You can read more here: http://www.carbochem.com/activatedcarbon101.html )
Activated charcoal is good at trapping other carbon-based impurities ("organic" chemicals), as well as things like chlorine. Many other chemicals are not attracted to carbon at all -- sodium, nitrates, etc. -- so they pass right through. This means that an activated charcoal filter will remove certain impurities while ignoring others. It also means that, once all of the bonding sites are filled, an activated charcoal filter stops working. At that point you must replace the filter. (You can read more here: http://science.howstuffworks.com/question209.htm )
Over 100 years ago Ellen White, a health reformer & pioneer of the Seventh Day Adventist movement strongly advocated the medical uses for charcoal powder. The modern medical establishment has only recently begun to use activated charcoal powder as the preferred method of treating oral poisonings and drug overdoses: "It is thought to bind to poison and prevent its absorption by the gastrointestinal tract. In cases of suspected poisoning, medical personnel either administer activated charcoal on the scene or at a hospital's emergency department. Dosing is usually empirical at 1 gram/kg of body weight, usually given only once. Depending on the drug taken, it may be given more than once. In rare situations activated charcoal is used in Intensive Care to filter out harmful drugs from the blood stream of poisoned patients. Activated carbon has become the treatment of choice for many poisonings, and other decontamination methods such as ipecac-induced emesis or stomach pumps are now used rarely." (From the Wikipedia entry for Activated Carbon)
You can find it at any fish & aquarium supply. If your concerned that the quality of the carbon from an aquarium shop might not be up-to-snuff, then go to a homebrew shop, or some other source that you are comfortable with. The granule size you'll want should be relatively close to 8 x 16 mesh size or smaller, but NOT so small that it falls out of the holes in your filter housing. I purchased the NSF approved carbon I used for my filters through an ebay merchant (here: http://stores.ebay.com/Carbon-Eze ). No, that's not me, & I don't know them. :) They describe their products well and have a good reputation & that's why I've included them here.
Step 2: The Polyethylene Plug
This is something you can find at a hardware store. They come in different colors and styles, so don't let that distract you... color isn't important and type is up to your own judgment. What is important is the size. You want a plug that is slightly over 1/2" at the widest point of the tapered sides. Vernier calipers would be a useful item to take with you to measure this dimension when you go to the store. This should cost less than 25 cents.
Step 3: Making the Hole.
You will notice on the top of the Brita filter cartridge some radial slots for allowing water into the filter. The overall diameter of the slot pattern is just under 1/2". I've drawn a black line where you'll want to make your cuts. As the plastic is thin, be careful not to get too happy with the knife... stay calm. :)
Dump out the original contents. You will notice what look like little glass beads in with the charcoal... I believe these are resin beads and are primarily used to remove heavy metals. Have your water tested to see if you have heavy metals that you would want removed. If so, you'll likely want to go with a filtration system that includes these beads.
As a side-note, some of the PuR filters (owned by Proctor & Gamble) now (as of March, 2008) come with a timed release version of sodium fluoride, which is toxic to mammals. You can read up on the fluoride controversy here ( http://www.fluoridation.com/ ), or you can Google the terms fluoride + poison. (2013 Update: PuR no longer sells their filters that "adds benificial flouride to your water")
Once you've got the hole roughed out, you can smooth it round with your knife, or you can use a 1/2" drill bit to ream out the hole. If you use the bit, set the drill on the higher gear range, as the faster bit speed will make a smoother, rounder hole. While you want a fast bit RPM, you want to insert the bit into your rough hole slowly so that you don't end up with tears in the plastic. You can actually use the fast moving bit to melt the hole, which will preserve the integrity of the plastic. Reversing the drill will provide friction/heat & help prevent tearing the plastic.
Finish up this step by trimming any excess plastic from around the hole and dry-fitting your plugs. Adjust the hole diameter with your knife as necessary... this isn't rocket science, the hole simple has to be tight enough to retain the plug so that the rim/shoulder of the plugs sits parallel with the surface, as shown in the photo.
Step 4: Filling & Using the Housing.
Before filling the housing, you may want to wash it then soak it in a bleach solution to kill any cooties that may have formed in the housing. Chlorine bleach, sodium hypochlorite, is a VERY potent antimicrobial, which means "a little dab will do ya". 8 drops of bleach per gallon of water is a stronger solution than any public pool or spa that I've ever been in and is the ratio that the World Health Organization recommends for purifying pretty ugly water for drinking. Personally, I think that ratio is overkill, but they probably want to err on the side of safety.
Rinse the housing thoroughly when done soaking... there's no need to dry it. Place the funnel in the hole and fill with activated carbon. You may want to tap the housing on your counter to settle the granules and top it off, allowing room for the plug. Once plugged, you now have a filter that is more than likely more effective at taking out impurities than the original. Why? because you filled it fuller and you used ONLY pure carbon with no fillers. It should filter more water before needing changed than an original filter.
You also may want to poke some holes in the "dome" on the top of the housing to allow water to flow into that area of the housing. A hot pin or needle works well for this. This replaces the holes that we cut out and plugged in step 3.
Treat this filter just as you would a new one... soak it in water for 15 minutes to make sure the carbon is saturated. Expect that there will be some fine charcoal powder that settles out in your first couple of batches or so. This won't hurt you to drink it with your water or let it settle out.. :-) When your filter is not in use, put it in a ziploc plastic bag and store it in the fridge to prevent it from growing funk. I haven't tried storing them in the freezer yet... that would definitely slow any growth down, but I don't know if it would cause the ice to break the carbon into finer particles that could escape the housing. I just haven't tried it yet.
This is my first instructable... questions, comments and critique are welcome and encouraged. Enjoy.
Step 5: ADDENDUM
ADDENDUM... MICROBES, FEAR, AND OTHER TOXINS....
I appreciate all of the comments... even the ones that ask the hard questions or bring up shortcomings or potential shortcomings in this instructable.
First off, let me say that this filter makeover is NOT intended to do ALL that the Brita filters claim to do, but just do what the activated carbon portion performs, which meets my needs very well. I live in a small community of about 50 individuals in the high plains of N.E. New Mexico, and the water hardness is just under 1000 parts per million (ppm), which are largely sulphates with some sodium, so we don't use that water for drinking or cooking. We distill some of our water in solar and electric distillers, and also collect rainwater from our metal roofs. Because of the quantity of dust, pollen, algae spores and other organic matter (bird poop, etc.) that settles on our roofs, we filter our water through a multi-stage filter bank that concludes with a .5 micron carbon block filter. Each week we consume about 250 to 300 gallons of rainwater alone, so water filtration is a requirement, but at the same time, we're not going to lose sleep over what get through the carbon. The filter pitchers that we use are primarily to remove any off-flavors that may not be entirely removed by the carbon block, and this the granulated carbon does remarkably well. Refilling these filters amounts to a substantial annual cost savings for us. In the last two months I've refilled over 30 of these filters with the NSF certified granulated activated carbon that I linked to on page 1 <http://stores.ebay.com/Carbon-Eze >.
Everyone should have their water tested and judge from the test results what type of filtration you NEED. Be intelligent. Why pay for something you don't use? Use your own judgment as to whether a carbon-only filter is suitable for your situation. I hate fear/ignorance stimulated marketing tactics that are used by some water filter companies (or any company) to get folks to buy their product out of fear and ignorance. I will try to dispel the concerns that some have suggested in the comments.
For those who are concerned that the quality of the carbon that they might encounter at an aquarium shop, and feel they need FDA "food grade" certification or on their activated carbon, I WOULD ENCOURAGE YOU TO FIND A SOURCE THAT YOU ARE COMFORTABLE WITH AND BUY FROM THEM. YOU MAY EVEN WANT TO SHARE WHAT YOU FIND... POST THEIR CONTACT INFO HERE in a comment. The carbon source I linked to sell NSF certified carbon. Really, though, I think the amount of concern over this point is overstated, as aquarium fish tend to be very sensitive to certain impurities and the folks that make the carbon for that application are very aware of this... they don't want anything in the filter media they sell, as it's not good for business. Personally, I would trust a vet supply (or aquarium shop) over the FDA any day of the week. The FDA approves toxins for food additives (sodium fluoride, Aspartame, MSG, etc.) while forbidding beneficial or benign ingredients (stevia, numerous medicinal herbs, etc.). It's usually about corporate money & bribes.
Anyone with a source for alternate or superior filter media are encouraged to post their findings and URLs in the comments.
For those with a concern about medications that may be in your city water supply (I'm assuming from the city recycling the waste water), if it's a carbon based/organic medication, then carbon should filter that out. Do your research, be responsible, be wise. Do what works for you.
If you have a concern about the carbon becoming a medium for microbes to flourish, one of the best ways to slow that process down is to lower the temperature of your filter by keeping the pitcher in fridge. Keep in mind that carbon removes (adsorbs) organic, carbon based impurities as well as chlorine... which also includes what decomposing residue that results from the organic impurities "rotting" that get caught by the carbon... molds, fungi, yeast, mildew... microbes in general. In other words, the "fresh" stuff that gets trapped by the filter and begins to decompose remains to be trapped by the carbon UNTIL the carbon has reached saturation. Unless your olfactory senses are totally fried, you should be able to tell by the taste of the water when the carbon is spent and in need of replacement. If you're one that is ultra sensitive to this kind of stuff, find out what works for you and stick with it. If you sleep better by using a corporate, consumer grade product, then by all means, do that.
If you're filtering water that has chlorine in it, the chlorine will likely reduce/retard/prevent the growth of microbes. The chlorine probably already killed all of the cooties BEFORE you ran them through the filter. Myself, I wouldn't worry about it unless you truly have a real and not imaginary need for additional filtration.
A WORD ABOUT DISCLAIMERS:
I purchased a book several years ago titled "The Egoscue Method of Health Through Motion" which had a disclaimer that really impressed me... it is included below and applies to this instructable, as well as life in general. Personal responsibility isn't for everyone, just those who appreciate freedom and don't care to blame others. :o)
"Ours is a highly litigious society. Which means, in plain English, we like to sue each other, blame each other, transfer responsibility to others.
Since, as you'll see, responsibility is a continuing theme of this book, the space which is usually reserved for what the lawyers refer to as the "disclaimer" is being used to make an additional and, I believe, more important point.
You've seen the words many times: "The following material is not intended as a substitute for the advice of a physician. The reader should consult a physician before embarking on this or any health program..."--- or words to that effect. The all-purpose liability firebreak.
Disclaimers are a legal necessity, but they are a cop-out. This material is no substitute for the reader taking responsibility for his or her own health. Therefore, I have an important recommendation to make: If you really need a disclaimer, close the book and put it back on the shelf unread.
I hope you don't, because what I have to say in the pages ahead will change your life. Pete Egoscue"
A COUPLE FINAL THOUGHTS/OPINIONS:
Anyone who is truly concerned about their health and is still eating meat and diary products are either ill informed or are not really concerned ENOUGH about their health. I would say the same thing applies to living/working in the city environment... it's not physically or spiritually healthy. I haven't been to a hospital for an illness in over 24 years, and the last 17 of those years I've been a vegetarian. I haven't been sick for almost three years... ever since I gave up eggs and dairy. I know about 50 other vegetarians who also stopped eating eggs and dairy products at the same time who also haven't been ill in almost three years. Be wise with what you do with your life.