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  1. #21

    Re: House water filter system

    I’ve been giving this a lot of thought lately and I’ve come to the following conclusions:

    I can no longer see the need to add bleach/peroxide when filling up, as the city supply should already be germ free. They treat the water with chlorine before they send it to you and in the proper proportions. It’s already in there. If you add to it you could end up hurting yourself.

    When storing water in a tank there is the potential for crap to grow. UV lights are good for dealing with critters if they start growing and regularly shocking the fresh water system (water tank, accumulator, hot water tank, plumbing, fittings) will kill anything in there no matter where in the system it may be living. And you’ve got to filter this dead crap out or you’ll end up drinking or brushing your teeth with them.

    Perhaps our focus should be on keeping our fresh water system as clean as possible instead of treating water that has already been treated.

    For peace of mind, whether you drink the water or not, is to filter what comes out of the system and have a water testing program in place. Without a testing program you just can’t trust that the water is clean after it comes into contact with the boat, and it is the only way to know for sure whether your water systems are clean and in good shape.

  2. #22

    Re: House water filter system

    I agree. Shock it, so you know that it's clean, and then use it. And by using it, I mean don't use a dockside pressure hook-up. If you don't continually replace the water in the tank, it will not continue to be safe to consume. But, if you start with a clean tank (after shocking it) and you continue to use already treated water (from the municipal supply), then you should be good for quite a while. The real problems come from the lack of use. This is why all of the liveaboards don't seem to have the problems that the weekenders have.
    Sky Cheney
    1985 53EDMY, Hull #CN759, "Rebecca"
    ELYC on White Lake--Montague, MI

  3. #23

    Re: House water filter system

    Peroxide is a perfectly acceptable disinfectant for water, as it oxidizes, as does chlorine. There are couple things with peroxide that make it different from chlorine as a disinfectant. Peroxide degrades even more rapidly than chlorine and potency may be an issue if it is to be stored.

    The other thing that makes peroxide more difficult to use is that testing for peroxide residual levels is difficult compared to testing for chlorine residuals. Residuals need to be measured to ensure disinfection is complete. This is dependent on the bacterial loading (how many "bug" part per million parts of water) of your water source. There are various methods of testing for bacteriological levels, but measuring residual levels is much simpler.

    "Residual" is that which remains from the original dosage and has not unreacted (potentially to prevent reinfection). Example: if one cup of water has 20 parts per million 'bugs' in it, the disinfectant dosage needs to be at least 20ppm but no more than 25 to prevent ill effects. A dosage of 23ppm (of the active chlorine component) will show a 3ppm free residual while showing a 23ppm total chlorine level (if the background is zero). In other words, the chlorine taste in the water is the "unused" chlorine left in the water after it has killed the "bugs".

    Peroxide would potentially have the advantage of breaking down to oxygen and water, but its use is also made more difficult by that fact when measuring reacted components. Because it breaks down faster than chlorine, its “staying power” is not as good as chlorine especially in an open container…which our water tanks are due to the fact they are vented.

    A quick calculation to use hydrogen peroxide daily is the required dosage in parts per million, times the volume treated in gallons, divided by 120,000 (which is a constant). This calculates the number of pounds needed to give that dosage. Simple enough?


    The short of the long is that a teaspoon (0.6 fl.oz.) of hydrogen peroxide (10-25% solution… look for this on the bottle) per one gallon of water in the appropriate ratio to render potable water. This is essentially double what is required for the use of chlorine bleach.

    For a live aboard, who is using a lot of water and continually cycling water through the tank, hydrogen peroxide may be a good choice as long as you are diligent about adding the hydrogen peroxide. For those of us who are weekend warriors of for those who are taking on “questionable water”, bleach is a safer bet especially when used with a simple household type filter with charcoal to remove the “residual” chlorine before it leaves the tap. The “residual” will slowly oxidize or be diluted as more water is added.

    I hope this was helpful.

  4. #24

    Re: House water filter system

    I always find discussions of poteable water interesting, but also see a lot of mis-information included in them. So, I'll jump in here with my 2 cents worth as a four year liveaboard, a 30+ year weekend warrior and a research chemist who spent 10 years trying to understand the effect of poteable water on plastic plumbing.

    The water we drink is way more complicated than the chemical symbol H2O suggests. Because it is the closest thing we have to a universal solvent, pure H2O doesn't exist outside of carefully prepared lab specimens. The water we drink has many chemicals and microbes in it. Most are good for us (minerals) and some of the microbes are not.

    Preparing water for distribution to our homes is a science of its own, and unfortunately not always well understood by the smaller water companies in the smaller cities of the US. However, they all need to meet well established criteria for drinking water; toxic chemicals, carcinogens and microbes must be kept to a minimum. Unfortunately, our standards do not include maximum levels for chlorine as they do in Europe. Most of Europe used to set 0.1 ppm chlorine as a maximum where here that is pretty much the minimum you find. So we find residual free chlorine levels vary from 0.05ppm to nearly 10ppm. You don't want to drink the latter. A microbiologist once told me 10ppm chlorine in water will kill a horse. But that level is rare, and you can smell it if you sniff test a glass half full.

    I mentioned carcinogens. When source water contains certain organic materials such as the flora and fauna in surface water (lakes & rivers), carcinogens called trihalomethanes (THM's) can form when chlorine is added to disinfect the water. To avoid this, disinfection is accomplished with alternative methods most commonly using 'combined' chlorine in the US. If you have something growing in your water system, you will likely generate some THM's if you add chlorine.

    In spite of all this, municipal water is almost invariably safe and has enough residual disinfectant to remain so in modest storage so long as you don't run it through a charcoal filter which absorbs the chlorine residual. Bottled water however has no uniform standard. Studies have shown that bottled water can be risky and is frequently or maybe even usually less 'safe' than municipal water. Consider the stuff you get from the local RO system at the supermarket. Does it get tested for quality? When? By who? How about that bottle that you might refill?

    So my point is the city water you bring on the boat is likely to be better for you than the bottled water providing you maintain your water system correctly. This includes the delivery hose. We have been drinking the tank water on our boats since at least 1979 and have never had a problem. I can't remember having shocked the system more than a few times in those years only to find out I didn't need to.

    What we do is simple starting with a suitable, clean hose.. First, never take on water from a marina that uses a well, unless there is no alternative. Always look for city water. If you must take on well water, then and only then would I consider adding some chlorine, say 0.1ppm. Otherwise, put clean water in a clean system and use it for everything. On Chateau de Mer we carry 180 gallons and that can carry us two weeks if we are cruising and being frugal, less if we are at a dock and enjoying a water source.

    The alternative of using dockside pressure water has several downsides. The water in your tank will get stagnant and you won't want to drink it if you go off for a cruise, the delivery hose that sits in the sun all day will produce green water that will get into your system, and if you are as forgetful as I can be, you might go off and forget to turn off the water.

    What about filters? Well, if you are using tank water regularly, you probably don't need one. There is not a lot of sediment that gets into city water. The 'taste and odor' filters that have some charcoal in them can be beneficial, and I use them in certain circumstances, BUT they also have a downside. The charcoal that is supposed to remove odors also removes the residual chlorine that you want for disinfectant. When this happens, the very high surface area of the charcoal that does the absorbing also provides an excellent medium for growing bacteria! That is the slime and foul odor you get when you pull one out. And also have a look at the cannister. It will likely be dark or black on the inside. If you must have a charcoal filter and want to minimize the smell from growing bacteria, you can try the 'silverated' filters. These have a fine coating of silver on the charcoal which which acts a biocide. They do retard the growth of bacterial slime a bit, but are not worth the added cost IMHO.

    Here in south Florida where the water is high in sulfur, I find the smell generated by the filter builds up too fast; so I don't use it here. When north, we leave it in because it is plumbed already.

    Now on to adding chlorine for shocking or maintenance. The city of Miami shocks its water system each year just before the snow birds arrive and start to increase the water usage. The water district told me they use about 10ppm chlorine to do this and that is enough to drive out all the bacterial crud that forms over the summer. And 10ppm ought to be the maximum you use for shocking your system if it really needs it (first make sure the filter is not the cause of the unpleasant taste and odor). But keep it to a minimum. Remember there are a lot of organic components in a boat water system that will be degraded by chlorine, even miniscule amounts. It's progressive.

    For maintenance, once you have a clean system that you are using regularly, you do not need to add extra chlorine. Most all of us can trust our municipal supply. If for some reason you want to add chlorine, keep it to 0.1ppm.

    My $.02.

    Bob

    PS, when we used to have to winterize, I found the best approach was to drain all the water out, use a wet vac to suck as much of the water as I could remove, and just leave the taps open. In the spring, I'd purge the first tankful and begin to use the water. No residual taste from antifreeze. Now if you were using vodka....

  5. #25

    Re: House water filter system

    Quote Originally Posted by DeeRow
    Mike,
    Do you plan on using the water when you don't have 110v available? Will this contaminate the water in the lines if it doesn't run thru the UV? I also would be concerned about drawing down the batteries with the 12v uv light. I guess that you could replace your FW pump with a 110v pump so that only treated water is passed thru the system.
    Mark

    Here in S FL it's a rare day I don't have 110v available so I'm not really concerned. What I was worried about was running a 12v UV lamp and loss of shorepower while away for a week. A 12v UV system is safer (water quality wise) but not worth the risk IMHO.

    I've started the installation and in the process decided not to install the 5 micron pre-filter. I'll use the .5 micron carbon and the UV for this summer and see if the filter life is acceptable.

    Bobk, Interesting reply on clorine and filters, please chime in on my situation. My home dockside water is well water, excellent water but non-clorinated. In the Bahamas almost every out island is RO and non-clorinated so each fill-up would pretty much require a shock to be safe. In the past I would add a "glug" of bleach on each re-fill, now I will measure but shocking every time doesn't make sense. As for the carbon filter I understand it removes the clorine I added but it also reduces cysts and metals, etc. basically makes the water "clear" so the UV can do its job. Plus my 500 lb per day ice machine requires a carbon filter. Am I screwing up somewhere? Mike

  6. #26

    Re: House water filter system

    Quote Originally Posted by Mike36c

    Bobk, Interesting reply on clorine and filters, please chime in on my situation. My home dockside water is well water, excellent water but non-clorinated. In the Bahamas almost every out island is RO and non-clorinated so each fill-up would pretty much require a shock to be safe. In the past I would add a "glug" of bleach on each re-fill, now I will measure but shocking every time doesn't make sense. As for the carbon filter I understand it removes the clorine I added but it also reduces cysts and metals, etc. basically makes the water "clear" so the UV can do its job. Plus my 500 lb per day ice machine requires a carbon filter. Am I screwing up somewhere? Mike
    If your water is free of microbes as it goes into the tank, you should not need more than 'maintenance' levels of chlorine. Check the pH. If above 8, you might maintain 0.5 ppm free chlorine. If down near 7, 0.1 ppm is adequate. The reason for the difference is complicated to explain in a short post, but the oxidizing power of chlorine is very pH dependant. You need less at lower pH.

    The carbon filter (common taste and odor filter as from Home Depot) will absorb soluble organic matter but does little to remove metals and I don't think it does much for cysts unless they are of the size to be trapped by the filter. I suspect they are small enough to go through the typical filter. You need a water softener to take out metals such as copper, iron etc.

    Bob

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