When you are mobile, in a boat, an RV or a tiny house, unless you are in the pristine mountains, it can often be difficult to find clean, safe, good tasting water. In the Southwest there is so much calcium and magnesium in the water that you can’t get a lather in the shower and white residue is everywhere! In the great lakes area, many places have iron totally dissolved in the water and you get red staining.
Everywhere you go, there is sediment and chemicals in the water, whether it is chlorine and fluoride in the cities or nitrates in well water. And then there are the pathogens – cysts (giardia and cryptosporidium), bacteria and viruses. So what can you do to be safe?
One option is to use Reverse Osmosis, which removes just about everything from the water, or you can get close to RO purity by using a combination of resins, carbon and mechanical filters.
Mechanical or Sediment Filters
Mechanical, or Sediment filters are rated in microns (one millionth of a meter). A human hair is about 50-70 microns in size for reference. The finest mechanical filter is Reverse Osmosis (RO), which is so fine that it can remove even totally dissolved minerals from the water. There are some challenges with RO, which will be discussed in a future blog entry. There are two classifications of mechanical filters, absolute and nominal. Absolute will remove everything larger than the rating. Nominal is an average, and will let a percentage of larger particles through.
Carbon Filters
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How About My Taste and Odor Problems?
The contaminants that affect the taste and odor of water will go right through a sediment filt
er, so you’ll need to add something else to remove them. The most commonly used method of cleaning up the taste and odor of water is passing it through a bed of activated carbon. The carbon has an uncanny ability to grab onto the bad stuff in water, leaving the water very clean-tasting and odor-free. Like a sediment filter, though, a carbon filter can only pull out a finite amount of contaminants, so it has a certain life expectancy. However, it is not possible to clean a carbon filter, so they must be replaced. Generally speaking, carbon filters will last twice as long as sediment filters, but they’re also more expensive.
What are NSF Ratings Used For?
The National Sanitation Foundation (NSF) is an organization that tests filters and rates them on their ability to remove chlorine from water. A filter must remove 75% to 100% of the chlorine to receive a Class I rating, 50% to 75% for a Class II rating and 25% to 50% of the chlorine to obtain a Class III rating. These ratings apply only to carbon filters.
Granular Carbon Vs. Carbon Block Vs. Modified Carbon Block
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GAC – Granulated Activated carbon, in the form of small granules, has been used for centuries to purify water. It works well and is still available in that form, but there is now another choice in carbon filtration.
- Solid Carbon Block – In order for any carbon filter to remove contaminants from the water, the water must come into contact with the carbon. In granular activated carbon (GAC) filters, the water can create channels that enable some of it to pass through without being affected. In solid block carbon filters, channels cannot form, so it forces the water to come into contact with the carbon. One result of this is that solid block filters have a higher NSF rating than a GAC unit. Also, due to the way the carbon blocks are formed, the pathways through the block are very small, and carbon block filters often have a small micron rating, which enables them to remove cysts and some other microbial pathogens
- Modified Carbon Block – New technology enables manufacturers to produce filters in the form of porous solid blocks, which are superior in every way to filters made of granular carbon. The latest technology in carbon filters is the so-called modified carbon block, in which filter blocks are built from fibers in a slurry of carbon particles. These filters are very similar in ratings to an equivalent micron model solid block filter. They offer a better flow rate, longer life through increased depth capacity, and a variety of micron sizes, all at a price that is equivalent to the solid block units. These carbon filters are very successful with RV use and for many RV customers, have proven to be the most effective and popular choice they can make. They are naturally resistant to stagnation because of the fiber material they are made of. The F5 and F1 models have become our best selling carbon cartridges by far.
- What is KDF and Why Would I Want It? KDF is an alloy containing zinc and copper that can be incorporated into carbon filters to make them bacteriostatic. That means that bacteria cannot grow inside the filter. This is particularly good for people who use their RV intermittently, and do not want to empty their canisters of water as KDF will protect the filter while the RV is not being used. A word of warning, Solid Carbon block filters with KDF should be kept submerged in water for their life after installing into the canister. If they are removed and dried, they may seize up and not pass water on the next use. There are several other chemicals that manufacturers use to make their filters bacteriostatic, but many of them affect you as well as the bacteria! KDF has a very good record as being the safest agent yet found for keeping bacteria from growing in filters, although silver nitrate is common, also.
What about Hard water with Scales?
“Hard water” is used to describe water with a high PH, alkalinity, and scaling/spotting on surfaces. This is caused by a high level of calcium and magnesium in the water. The photo below shows a shower head that has been exposed to hard water for a period of time. 
To remove it, you need a resin that does an ion exchange, known as a water softener or….reverse osmosis. The resin in the water softener is charged with sodium ions using table salt, then is flushed to remove any salt taste. When water with calcium, lime and magnesium hits the resin, the “hard” ions are replaced in the water by the “soft” sodium ions. This effectively removes the hard elements and softens the water.
How Do I get Higher levels of Purification?
Removing the aesthetic issues from the water (taste/odor, sediment, chemicals) is a good start, but you might want more. To remove bacteria, for example, requires a ceramic filter, a UV light or reverse osmosis. To take out fluoride, arsenic, iron and other totally dissolved solids from the water may require a special resin filter or again….reverse osmosis. Under sink filter systems are great for taking out the difficult to remove minerals and potentially toxic substances from the water. I will be covering each of these filter types in future posts.
Thanks and SAFE TRAVELS
RV Water Doc
