Foul tank water is completely preventable. Here are some dos and don'ts for a healthy water tank. Dont place glycol or other winterizing agents in the tank. Install valves as needed to winterize the pipes only; typically a tee and two valves located near the tank drain work fine.
Leave water from any source in a storage tank for a while, and interesting things will start to grow. Only the purest water in an airtight bottle will have a long shelf life. But not all bottled water is what the label says it is. For a cruiser, there are two water-testing tools that are important, and a third tool that is helpful in determining what is going into a tank and managing the quality of fresh water on a long-range cruising boat.
You would think that with all the emphasis cruising sailors put on their boats and equipment, we would pay a little more attention to ensuring a clean and safe supply of water. This is less a concern in developed countries, where dockside water is safely treated or bottled water is affordable and readily available. However, once you begin to expand your horizons, ensuring a clean water supply requires more thought and effort. This is the first report in a three-part series on equipment and practices that no matter where you and your boat are, you can be reasonably sure that your on-board water supply is safe.
Ever find a bug doing the backstroke in your water tank? We have. Would you leave a glass of water sitting uncovered for weeks and then come back to it? Of course not, but many builders either lead the hose to a mushroom-type through-hull fitting, or terminate it inside the cabin, with nothing to keep the ubiquitous critters from seeking shelter, fresh water, or a nesting site.
When it comes to onboard water tanks, we prefer stainless, fiberglass, and even roto-molded tanks (in that order) to aluminum ones. Aluminum tanks tend to pit and corrode over time, often needing to be replaced. The insides of the two 60-gallon aluminum water tanks in our 30-year-old Valiant 40 were more like a nasty moonscape than a drinking source. Their surfaces were pitted and rusted from what looked like a reaction to long-time use of chlorine.
When contributor Drew Frye commissioned his familys PDQ 32 catamaran six years ago, his daughter asked, What are these pink lumps in the sink, Dad? The toilet bowl was even more spectacular, a science project in a dozen hues of pink, green, yellow, and black. The boat had been winterized for some time, down in south Chesapeake Bay, where winters are mild and many boaters and don't take freezing seriously.
When testing a chemicals toxicity and its ability to biodegrade, a common procedure is to dilute each target chemical at various ratios of interest, and then to inoculate each with an acclimated microbiological seed. For our test, the seed was developed by filling a five-gallon bucket with several gallons of water and a weak mixture (two percent total glycol content) of all of the winterizing agents to be tested.
Protecting marine water systems from freeze damage is a deceptively simple goal. The terminology and various product claims can be confusing, and what seems like a good common-sense decision can lead to trouble. We tend to think that all water systems are the same; that boats as well as RVs can be protected by the same pink antifreeze without any further thought. However, many of the problems we associate with age, or normal wear and tear-stiff impellers, cracked pipes, ruined joker valves, and foul-tasting tap water-can often be attributed to errors during winterization.
We tested each product for glycol content using a refractometer and either the ethylene glycol or propylene glycol scale, as appropriate. In the case of Camcos Arctic Ban and Sudburys Winter Stor, some portion of the freeze protection is provided by ethanol, and such mixtures cannot be easily evaluated by any field method (test tape, gravity, refractometer) unless the exact proportion is known, which we find troublesome.