By Ken Hughes

“Water, water, everywhere, and all the boards did shrink; water, water, everywhere, nor any drop to drink.”

Prophetic or not, when penned by Samuel Taylor Coleridge for his “Rime of the Ancient Mariner” in the early 19th century, those few words ring closer to the truth with every passing year.

Pure, fresh and safe potable water is taken for granted in much of the “developed” world. However, there has been an increasing incidence of E. coli, Giardia and Cryptosporidium contamination in modern, big municipal water distribution systems worldwide. Among others, the cities of Milwaukee and Sydney, Australia, have experienced water contamination problems with Cryptosporidium oocysts and an Ontario, Canada, town recently had a significant problem with E. coli in the city water.

Out at sea
In the marine industry, however, potable water is whatever is in the holding tank, regardless of the quality of the original source. In order to make fresh water, yachts and ships may use multi-pass reverse osmosis (RO) systems and larger vessels may also have vacuum-assisted distillation systems. Both systems produce pure fresh water, which is then stored in a steel, plastic or fiberglass holding tank. That’s the point where all bets are off, as even the purest water can be recontaminated while in the tank. Anyone who has spent much time at sea and consumed water from a holding tank can attest to the disgusting water they may have endured on occasion. Documented cases exist where entire crews were incapacitated from consuming contaminated water from holding tanks. Numerous cruise ship passengers have become ill from Legionella bacteria ingested from swimming pools, spas, and even the ship’s potable water system.

The nature of most yacht owners is to cruise to that out-of-the-way, exotic location. And commercial vessels certainly stop at remote ports of call in the pursuit of trade. While tied to the pier, commercial vessels—and most yachts—will take aboard water from a dockside hose connection or a water barge. Operators of the water treatment plant from which the water is drawn may not know and, in some instances, may not particularly care about the purity of the water going down the pipe. As populations worldwide (and especially near coastlines) have continued to spiral upward, the more likely scenario faced is an overloaded treatment plant that can no longer successfully disinfect the large amounts of water being processed.

Chlorine vs. ozone
Chlorine-based water treatment systems have greatly benefited mankind, and have been largely responsible for the decrease in waterborne diseases such as cholera, typhus, typhoid and diphtheria. However, there’s ample evidence that chlorine is falling down on the job at levels of concentration now considered safe as evidenced by contamination of municipal chlorine-based treatment systems in Milwaukee and Sydney. In Milwaukee, 400,000 citizens were infected and over 100 died. Further, the consumption of chlorinated water has been directly linked to bladder cancer in men, due primarily to trihalomethanes (THMs), resulting from the partial oxidation of organics by chlorine. As a result of U.S. Environmental Protection Agency (USEPA) mandated reductions in the amount of THMs in treated water in the United States, many plant operators have been left with little choice but to turn to ozone or other alternative disinfection methods.

Ozone, in fact, has a very long history in municipal water treatment, first being used in 1906 in Nice, France. The use of ozone as the prime oxidizer in municipal water treatment plants is rapidly expanding to many cities, including Milwaukee. The 75-year-old Lee Hall water treatment plant for Newport News, Va. and surrounding counties is just now being converted to an ozone-based system. Its public utilities director, Brian Remaley, stated ozone “should be more effective as a disinfectant, and make the water taste better (since)… with ozone, you don’t get the chlorine taste.” Remaley said the chlorine taste was his No. 1 customer complaint.

For many years, yacht owners and captains have made a practice of pouring bleach directly into holding tanks and hoping for the best. Many owners, captains and engineers will tell you they just “poured some in until it seemed about right,” a practice that could truly be an instance of the cure being worse than the disease. Unregulated introduction of chlorine into potable water holding tanks could have very serious implications for the health of those consuming the water.

Facing obstacles
Larger vessels usually have automated chlorination or bromination systems for potable water, with the latter becoming more popular than the former, primarily because of disinfection by-product (DBP) problems (such as THMs) associated with chlorine that have made its use less than politically correct. Unfortunately, bromine has a taste that’s worse than chlorine. It also has DBPs (bromate) and is not as efficient in disinfecting water. Clever packaging has made bromine—which is normally very dangerous to store or use—more convenient to apply. However, few if any like the taste and often pine for the “good old days” of chlorine.

There are two other major marine industry problems, sewage and ballast water discharges, both of which can be solved with ozone and for which applications are currently being engineered. The International Maritime Organization (IMO) has amended its recommendations to encourage operators of “Marine Sanitation Devices” (sewage treatment plants) to use ozone, UV or any disinfectant other than chlorine. The IMO has finally acknowledged the problems created by the unregulated discharge of chlorinated waste—a fact that Greenpeace, among others, has pointed out for many years. Some organic compounds—when partially oxidized by chlorine—mimic numerous hormones that affect growth and development of many species (human beings included), and are also linked to cancer at certain levels.

Ozone has a secure future in marine applications that are truly international in scope. There are presently several hundred ozone systems roaming the world on board some of the largest and highest profile luxury yachts and research vessels in the industry. The units are doing everything from purifying potable water to killing the odors and fumes from sewage holding tanks, as well as destroying odors in the yacht or ship’s interior and bilge areas, and thereby making life aboard yachts and ships much safer, and more pleasant in the process.

About the author
Ken Hughes is a native of Eden, N.C., where he and wife Diane owned and operated a research and development company before relocating to Fort Lauderdale, Fla., to found Delta Marine International Inc. in July 1993. The R&D operation specialized in systems and devices for the printing, packaging and publishing industry. Hughes’ first work with ozone was in an automated—and now widely copied—aqueous chemical mixing, monitoring and conditioning system for an offset printing press fountain solution. DMI’s product line—Chem-Free Marine Ozone Systems and Devices—presently has dealers for the equipment in England, Singapore, Australia, the Bahamas and New Zealand. More information can be found at: or

Foreign Invasions: Zebra mussels and disinfection
There’s a massive, but very quiet and unseen, invasion under way in American waters from coast to cost and all throughout the Great Lakes. It’s source is the holds of ships traveling internationally from port to port.

When a ship isn’t carrying sufficient weight in cargo or fuel to make it float in a stable and safe manner—and keep the propeller(s) and rudder(s) properly submerged—it must have on board what’s known as ballast. In early days, that may have been rock from shore or brick, or anything else handy that could be discarded when cargo was brought on board. Discarded brick ballast is the reason brick homes first became popular in port cities. It didn’t take long to realize water made great ballast. It was easy to obtain and equally easy to discard when cargo was loaded. Unfortunately, there were many species of marine life drawn in along with the ballast water, which were then dumped at the next port of call.

The newly introduced foreign critters are non-indigenous to the local marine ecosystem, and are known as “invasive species.” Perhaps the best-known in American waters is the Zebra mussel. This small, prolific breeder was imported from central Europe in ballast water and dumped into the Great Lakes where it has no natural predators. The latest is the “Fish Hook Flea,” a small crustacean that came from the Caspian or Black Sea, and is now in the Great Lakes as well. The Russians even warned the United States the flea may be on the way and nothing was done.

The estimated annual cost of damage from invasive species in the United States alone is $128 billion! That’s more than the combined cost of all other natural disasters—including floods, fires, earthquakes, tornadoes and hurricanes—in the United States every year. Unfortunately, America isn’t alone in dealing with the problem, as invasive species show up wherever ships carrying ballast water make port calls. Combating invasive species will prove to be the costliest world war ever waged.

A partnership in November 1999 was formed with Scripps Institution of Oceanography, San Diego, CA; Woods Hole Oceanographic Institution, Woods Hole, MA; and NOVA Southeastern University Oceanographic Center in Fort Lauderdale, to finalize development of an ozone-based ballast water treatment system that was first demonstrated in 1995.—Ken Hughes


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