Friday, 06 November 2009 00:00

Let’s talk water filtration

Now that it has become quite evident that the purchase of bottled water is one of the most notorious causes for the pollution of our oceans and environment as well as one of the biggest scams of the century, it is time to evaluate how we are to deal with the issue of drinking water that is produced from our municipal water sources. It is not a simple subject.

 Not all water is created equal

   It has been proven time and again by researchers that the water found in most bottled water is not as good as the municipal water sources for household tap water in most western countries. Municipal tap water is tested every day to conform with mandatory regulatory standards however bottled water may be inspected only three times a year at most. Scary – isn’t it!

   Even the best bottled ssq_int_02pring water has been proven to have many traces of chemicals in it due to the contamination of water tables in addition to the BPA found in the PETE #1 plastic that it is bottled in. Granted, both bottled water and municipal tap water are filtered and treated with chemicals to improve it, but municipal tap water is balanced to a neutral PH of 7.0 which is the standard for what is considered healthy for human consumption. Most bottled is very acidic which is very bad for the human body.

 Municipal, city water and spring water

  All city or municipal drinking water goes through a maze of processing and filtration before it ever reaches your tap even if it is spring water. Raw, unclean water enters the system and is then passed through a fibrous bed of either sand, fine gravel, synthetic floss, or a combination of all three. This mechanical filtration removes sediment and some cloudiness. Activated carbon and other substances then leech harmful toxins out of the water in what is known as chemical filtration. A final stage of filtration is biological filtration. Some treatment plants actually run their water through plant life to absorb nitrates and other forms of nitrogen. Municipal water is tested daily whereas bottled water is tested no more than three times a year at the manufacture plant.

 How do we improve on typical tap water

  Water filtration and treatment of all shapes and sizes are available for homes and yachts. These filtration and treatment systems not only eliminate bacterias and other viral contaminations but they can also eliminate chemicals, and adjust PH and thus create healthier and better tasting water.

Where to start?

   If you are joining the numerous individuals and yacht crew who are switching over to use the tap water onboard, here are a few suggestions as to where to start to test and evaluate your water treatment systems onboard.

Water quality maintenance

sq_int_02b   The first step is to test your water coming to the yacht from the dock and also onboard from a drinking water tap source and from any ice makers. Test for both bacterial contamination, chemicals and PH balance. A normal PH balance for alkaline or acidic is 7.0 for most regulations from municipal water sources. There are many different kinds of water testing kits available online and here are a few web sites to check out.,, Testing your drinking water will give you a good idea as to how to proceed with further filtration and maintenance.

Clean the water tanks

  This is a commonly overlooked maintenance task. It is easy to include this procedure in an annual tank cleaning scheduled maintenance plan. Quite often the same company that cleans the fuel tanks and waste water tanks can also clean or arrange for the cleaning of water tanks. It is not an expensive process and can be done quite quickly and efficiently depending upon the yacht's tank access configuration. If you are unsure when the last time the water tanks were cleaned then it is best to schedule this task in the next yard period. A scheduled maintenance plan should be mandatory onboard any professionally operated yacht and it should include all maintenance to water treatment and filtration as well as tank cleaning.

Determine what water filtration is installed onboard

   Make an assessment of what water filtration is already onboard. This should include any UV filtration, RO or reverse osmosis (watermaker) filtration, carbon and sediment filtration at local taps in the galley, panty, service bar, cabins and crew quarters.A good quality water filtration system should at the least include a combination of all of these.   Reverse osmosis, activated carbon filtration and ultraviolet sterilization are all complimentary processes.Combining them results in the most effective treatment against the broadest range of water impurities and contaminants.

 Change the filters via a scheduled maintenance plan

   Make sure that the filters for any of the filtration stages, whatever the type onboard, are clean and are included in the scheduled maintenance plan. Carbon and sediment filters are quite inexpensive in the scheme of things and a good supply of them should be kept onboard for quick replacement. Secondary filters quite often are of a carbon and sediment type.

 Carbon is a substance that has a long history of being used to absorb impurities and is perhaps the most powerful absorbent known to man. One pound of carbon contains a surface area of roughly 125 acres and can absorb literally thousands of different chemicals. Activated carbon is carbon which has a slight electro-positive charge added to it, making it even more attractive to chemicals and impurities. As the water passes over the positively charged carbon surface, the negative ions of the contaminants are drawn to the surface of the carbon granules.


   Activated carbon filters used for water treatment typically contain either granular activated carbon (GAC) or powdered block carbon. Although both are effective, carbon block filters generally have a higher contaminant removal ratio. The two most important factors affecting the efficiency of activated carbon filtration are the amount of carbon in the unit and the amount of time the contaminant spends in contact with it. The more carbon the better. Similarly, the lower the flow rate of the water, the more time that contaminants will be in contact with the carbon, and the more absorption that will take place. Particle size also affects removal rates.Activated carbon filters are usually rated by the size of the particles they are able to remove, measured in microns, and generally range from 50 microns (least effective) down to 0.5 microns (most effective).

   A typical filter system has from 12 to 24 ounces of activated carbon. The most common carbon types used in water filtration are bituminous, wood, and coconut shell carbons. While coconut shell carbon typically costs 20% more than the others, it is generally regarded as the most effective of the three.

sq_int_02eHow carbon filters work and their applications

   There are two principal mechanisms by which activated carbon removes contaminants from water; absorption, and catalytic reduction, a process involving the attraction of negatively-charged contaminant ions to the positively-charged activated carbon. Organic compounds are removed by absorption and residual disinfectants such as chlorine and chloramines are removed by catalytic reduction.

 Activated carbon filtration is very common in a number of water treatment systems. It can be used as a standalone filter to reduce or eliminate bad tastes and odors, chlorine, and many organic contaminants in municipal (pre-treated or chlorinated) water supplies to produce a significantly improved drinking water. It is also very commonly used as a pre-treatment as part of a reverse osmosis system to reduce many organic contaminants, chlorine, and other items that could foul the reverse osmosis membrane. 0.5 micron carbon block filters are commonly used to remove cysts such as giardia and cryptosporidium.

Carbon and sediment filters

   Activated carbon filters remove/reduce many volatile organic chemicals (VOC), pesticides and herbicides, as well as chlorine, benzene, trihalomethane (THM) compounds, radon, solvents and hundreds of other man-made chemicals found in tap water. Some activated carbon filters are moderately effective at removing some, but not all, heavy metals. In addition, densely compacted carbon block filters mechanically remove particles down to 0.5 micron, including Giardia and Cryptosporidium, turbidity and particulates. Although some iron, manganese, and hydrogen sulfide will be removed by these higher quality activated carbon filters, a manganese green sand iron reduction filter is generally preferred to remove these contaminants as the effectiveness of carbon filter against iron and manganese is generally short-lived if the contaminant concentration is high.   Carbon filters are NOT generally successful at removing dissolved inorganic contaminants or metals such as minerals/salts (hardness or scale-causing contaminants), antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, copper, fluoride, mercury, nickel, nitrates/nitrites, selenium, sulfate, thallium, and certain radio nuclides. Removing these contaminants requires either a reverse osmosis water filter system or a distiller (some can also be removed by KDF-55 or manganese green sand).

  GAC does not remove sediment / particulate material very well, so they are often preceded by a sediment filter. Sediment pre-filters also prolong the activate carbon cartridge life by eliminating gross contaminants that would otherwise clog the activated carbon thereby reducing the surface area available for absorption. Carbon block filters are generally better then GAC filters at removing sediment.

sq_int_02dHow the Reverse Osmosis System Works   Reverse Osmosis is a process in which dissolved inorganic solids (such as salts) are removed from a solution (such as water). This is accomplished by household water pressure pushing the tap water through a semi permeable membrane. The membrane (which is about as thick as cellophane) allows only the water to pass through, not the impurities or contaminates. These impurities and contaminates are flushed down the drain. It is effective in eliminating or substantially reducing a very wide array of contaminants, and of all technologies used to treat drinking water applications, it has the greatest range of contaminant removal.

  Reverse osmosis will allow the removal of particles as small as individual ions. While reverse osmosis can be very effective in removing bacteria and viruses, it is not recommended that reverse osmosis be the only level of purification for water that contains or may contain biological contaminants.   Reverse osmosis (RO) units remove substantial amounts of most inorganic chemicals (such as salts, metals, minerals) most microorganisms including cryptosporidium and giardia, and most (but not all) inorganic contaminants.

 Reverse osmosis successfully treats water with dissolved minerals and metals such as aluminum, arsenic, barium, cadmium, chloride, chromium, copper, fluoride, magnesium, iron, lead, manganese, mercury, nitrate, selenium, silver, sulfate, and zinc. RO is also effective with asbestos, many taste, color and odor-producing chemicals, particulates, total dissolved solids, turbidity, and radium. When using appropriate activated carbon pre-filtering (commonly included with most RO systems), additional treatment can also be provided for such "volatile" contaminants (VOCs) as benzene, MTBE, trichloroethylene, trihalomethanes, and radon.

  Essentially, reverse osmosis is capable of rejecting bacteria, salts, sugars, proteins, particles, dyes, heavy metals, chlorine and related by-products, and other contaminants that have a molecular weight of greater than 150-250 daltons. The separation of ions with reverse osmosis is aided by charged particles. This means that dissolved ions that carry a charge, such as salts, are more likely to be rejected by the membrane than those that are not charged, such as organics. The larger the charge and the larger the particle, the more likely it will be rejected.  The difference between carbon filters and reverse osmosis water filters is the method of filtration. The reverse osmosis water filter removes particles based on their relative molecular size, and since minerals and metals are larger than chemicals, the minerals and metals get stuck while the chemicals flow right through. Carbon filters bond chemically with the organics and synthetic organics which come from pesticides, agricultural runoff, and household and industrial waste, thus not allowing them to pass through into your glass. Therefore RO water is stripped of beneficial minerals.

   Another unexpected disadvantage of the reverse osmosis water filter is that it is very wasteful. Because of the nature of the process, for every gallon of filtered water produced by reverse osmosis, two to three gallons get wasted. Activated carbon filters do not waste water in this way, and so through carbon filtration there is not only better water but more water for us to drink.

UV sterilizer treatmentsq_int_02c

 UV is often the last device in a treatment train. UV radiation affects microorganisms by altering the DNA in the cells and impeding reproduction. UV treatment does not remove organisms from the water, it merely inactivates them. The effectiveness of this process is related to exposure time and lamp intensity. There is no residual disinfection in the water to inactivate bacteria that may survive or may be introduced after the water passes by the light source, which means that the UV unit should be located as close as possible to the point-of-use since any part of the plumbing system could be contaminated with bacteria.


   A water ionizer is an appliance that ionizes water. Ionized water is claimed by manufacturers to be extremely beneficial to human health and marketed with claims that it is an antioxidant which can slow aging and prevent disease. Others note that such claims contradict basic laws of chemistry and physiology. A water ionizer separates water into alkaline and acid fractions using a process known as electrolysis. It does this by exploiting the electric charge of the calcium and magnesium ions present in nearly all sources of drinking water. Comparing tap water to ionized water, the first difference is that tap water cannot penetrate your cells as well as alkaline water can. The beneficial negative oxygen ions that are so abundant in alkaline water, which help your body release acid residue, are introduced to the body through cellular penetration.

  The acidic waste water can also be used for effective cleaning purposes when it is adjusted for high acidic content. The process is similar to reverse osmosis in that it is wasteful and must produce a lot of waste acidic water in order to produce the high percentage alkaline water. When a source of water lacks mineral ions, such as distilled water, or has been filtered by reverse osmosis, water ionization has no effect. There is also no scientific data to prove that ionizers remove any chemical or biological contaminants. Ionizers are usually located at the tap source either on a counter top or under the sink.

Help save our oceans

   Most yachts are equipped with two or more of these systems onboard already. With proper scheduled maintenance and testing you should have no problem drinking the municipal water that is stored onboard and it should taste very good as well. As a direct benefit you will be helping to diminish the amount of harmful plastic that is accumulation in our landfills and oceans.stch_int_01

Monday, 14 April 2014 00:00

Go green & charter by Trish Cronan

Can a superyacht with its diesel-guzzling thirst and noxious emissions be considered eco-friendly?  Is it indeed an oxymoron to talk about going green on superyachts?  I say that if General Motors and Wal-Mart can go green, so can a superyacht.

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