Wednesday, February 23, 2011

Reverse Osmoses Water Filtration

"Water water everywhere, but not a drop to drink." 75% of the Earth is covered with water and 75% of you is water. I guess that stuff is important. And because it is so important I feel that putting the cleanest water into our body is also very important. When I was younger we use to buy our water from water vending machines. A dime to a quarter would buy you a gallon. I remember spending a few hours every couple of weeks to fill old juice containers and 5 gallon water jugs. At the time we could not justify the cost of getting drinking water delivered, so that was our alternative.

What is it about tap water that is so disagreeable, it is regulated by the government to meet safety standards. The main issue I have with tap water is the amount of chlorine that is added to the water to insure that it is free of live microbes. Chlorine is not only a toxin, but is not pleasant to smell and taste. At one house we live at the pines trees near the lawn had light colored bark the first 10 feet up. I finally figured out that the height of the bleach bark coincided with lawn sprinklers. Years of soaking in tap water had bleached the color out of the bark.
Sometime in my adolescent years, our family installed a Watts 5 stage reverse osmosis water filter under the sink. When I finally graduated college and moved out on my own, I purchased a similar system and installed it in five various houses which I lived in. Clean great tasting water without having to lug jugs from the vending machine and without the high cost of water delivery.
So what is Reverse Osmosis . You might have heard the term before and considered it some kind of filtration method. You are mostly correct. RO refers to not only the process but the membrane used. The RO membrane is pressurized on one side with the "dirty" water, the membrane then lets only water molecules through while larger ions are not allowed to pass. Rather than being forced through the membrane and trapped, the majority of solutes and ions remain on the pressurized side and are discharged. Because of this fact the RO membrane last much longer than a filter which traps all the undesirables and becomes clogged.

A down side to a typical home RO system is that it takes four gallons of water of make one gallon of processed drinking water. RO systems also take time to process the water. A storage tank is required to accommodate the processed water. There are RO systems that do not waste any water, but uses an electric pump to provide the adequate osmotic pressure. I am not familiar with the exact workings of this type of system. Does it still discharge some "dirty" water so the RO membrane does not get clogged? How much electricity does it consume? Is it better to consume extra electricity or waste a few gallons of water. I believe that a four to one ratio is hardly noticeable to the consumer. If you drink a gallon of water a day, you waste four gallons of water. The most efficient low flow shower heads all discharge at a rate above 2 gallons per minute. You do the math.

So what are the five stages of water filtration? The unprocessed water first enters the system and is processed by three filters. A pre or sediment filter, and two carbon block filters. These can be seen in the first picture as the largest, three equal size filters. These three filters do the bulk of removing contaminates from the water. The three initial filters are a standard size and can be purchased from any hardware store. Instead of the set up I just described (stock configuration), I have opts to use two sedimentt filters, a 10 micron and then a 1 micron, followed by only one single small pore carbon block filter. After being filtered by the first three stages, the water then enters the RO filter stage. The RO components sits horizontally atop the three first stage filters. This part of the system is the most complicated and includes pressure regulators and discharge lines. The dirty water is discharged into a drain line and the processed water goes into a storage tank. After four filtering stages the water is ready for drinking. The final filter is a carbon scrubber which removes any unpleasant tastes and odors that might have resulted from sitting in the storage tank. This final carbon filter is the same as the kind found on refrigerator ice maker. Finally the ready to drink water is dispensed through a tap which sits atop your sink.

Installation of the system is fairly easy. The filters are a free standing unit and can easily fit under most sinks. I have once placed the unit in a neighboring cabinet and simply ran the lines through a small access hole. Next you will need to tap into the cold water line. DO NOT USE HOT WATER for the system. The hot water will cause the filter membranes to expand and prevent water from passing. This has been known to cause filter systems to explode. The intake water is collected from a simple "T" fitting that is screwed in line to the line which delivers water to your faucet. The green line in the picture goes towards the RO system. A valve allows the intake water to the RO system to be shut off. This is helpful when maintaining the filter system as you still have water for the sink and dishwasher. The drain line is the only part of the system that is semi permanent. From the first picture you can see a transparent line connected to the sink drain line above the trap. A hole must be drilled into this pipe and a saddle installed. This is not such a big deal when the system is removed, as the hole is easily patched with a dab of epoxy. If a more professional solution is desired the length of pipe can be purchased for a few dollars and pre-treaded collars makes replacement a breeze.

The part that can be the most difficult in the installation can be the drinking water faucet. Most kitchen sinks come equipped with a minimum of three access holes, most come with more. The three primary access holes are intended to the used for a standard three hole type faucet. The other holes can be used for sink sprayers, soap dispensers, dishwasher vents, or drinking water faucets. In many of the rental homes, a unused hole was capped by an easily removed cover. In other homes I simply removed an unused soap dispenser or a sink sprayer. In my current home I had four holes in a stainless steel sink. I opted to cut a fifth hole so that I could retain my soap dispenser. Cutting a hole in SS is easy. If you have a porcelain sink, you might considered freeing up an existing hole. Porcelain is difficult to cut and can easily crack. One option is to use a single hole faucet in a three hole sink. Instantly you now have two accessory holes available. Another option if you have a sink top dishwasher vent is to get an under the sink vent, though this might be a function of the dishwasher and not so easily accomplished.
One interesting thing that I found out about these filter systems is what is known as an air gap. After installing the filter system at some locations a gurgling sound could be heard in the still of the night. I discovered that this was not caused by a troll living under the sink, but by the air gap. Many states require that an air gap system be built into plumbing. An air gap is a vertical space between the faucet and the drain that prevents contaminated water from flowing back up into the faucet. To tell you the truth I do not fully understand the mechanics of the system but know that it is required in California. Not all states require an air gap, thus you can find non-air gap type faucets for sale. I do know that having this air gaps opens up an acoustic path to the drain; and when the RO system is working a slight gurgling can be heard as waste water drains.
Is all this worth it, can't I just buy bottled water?? Since I have moved and installed this system into 5 different homes; my answer should be clear. If you drink bottle water exclusively, you should take one of those bottles and...

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