Registered users don't see ads

Aluminum Water Tank

Discussion in 'Marine Plumbing and Sanitation' started by firehoser75, Mar 6, 2018. Add this thread to a FAQ

  1. firehoser75


    Joined Oct 1, 2008
    148 posts, 3 likes
    Bavaria 36 Cruiser
    Ca Nanaimo, BC
    I am wondering if I need to add anything to my freshwater after I fill using a good quality filter. I am a bit concerned as the filter should remove all chlorine from the water, and maybe this gives some "critters" a chance to get started.
    Some background. When winterizing, I drain the water tank (aluminum tank) and water heater (also aluminum), and using the bypass add freshwater antifreeze to the piping which is the white plastic pex piping.
    In the spring, I run a mild bleach solution through just the piping, not in either tank or heater, followed by a good rinse. I then use the Thetford treatment system (does not contain any chlorine) on the water tank and the plumbing system following their directions. Everything is then rinsed well and then the system is filled using the fore mentioned external water filter.
    I have a 150 gallon tank and it takes about 3 weeks to go through that much water, and it can sometimes sit for up to 2 months from first fill to first use. Should I add some type of "sanitizer" to the drinking water in the tank (filtered again with a Nature Pure QC2 filter at the sink before drinking and cooking), and if so, what sanitizer for aluminum tanks.

  2. Don S/V ILLusion

    Don S/V ILLusion

    Joined Sep 25, 2008
    5,052 posts, 273 likes
    Alden 50
    US Sarasota, Florida
    Using bottled water saves having to sift through the numerous and often contradictory opinions and published standard methods of self-proclaimed experts.

    justsomeguy likes this.
  3. RoyS


    Joined Jun 3, 2012
    338 posts, 84 likes
    Hunter 33
    US Bay Pointe, Quincy
    Most municipal water sources have chlorine treated water to control organisms wishing to live in your drinking water. What has worked for us is to pre-filter the water filling the tank with a <1 micron non-carbon filter. This allows the chlorine but little else to pass through into the tank. After the pump we have a carbon filter that removes the chlorine. In the spring we shock treat the entire water system including the tank, once for the season. Peggy Hall can give you the details on that procedure. Our tank is also aluminum and 38 years old. We used to use bottled water for drinking but wished to cut down on the trash and storage required for all of the bottles.

  4. FastOlson


    Joined Apr 8, 2010
    971 posts, 95 likes
    Ericson Yachts Olson 34
    US Portland OR
    Probably not quite the answer you wanted, but consider changing out the water tank... for several reasons.
    Replace it with a couple of tanks with a manifold valve so that you can tailor your storage to your cruising plans. You may want to have about a 40 gallon "main" tank for general use, and a separate 100 gallon one for extended cruises away from easy fill-ups from the tap.
    On our smaller boat, we have cruised in the Gulf Islands with occasional stops for a fill, and we have a main tank holding 38 gallons and also a manifold-valved second tank of 23 gallons. That is 100% all of our drinking and washing water on board, cruising for a month at a time.

    Next, and with more emphasis, do NOT use aluminum for a water tank. Use SS or rotomolded plastic (lots of choices from the great folks at Ronco.)
    **Back in the 80's Hunter installed a ton of aluminum tanks for everything on their boats.... had corrosion problems galore with the ones for drinking water and for holding tanks. The tank salesman must have been Really Persuasive. :)
    Same caution for the inner tank in your hot water heater, or calorifier as they say in the UK. We replaced our hot water tank many years ago when we found that it's inner aluminum tank was generating a gritty white (sort of) aluminum oxide material that was going thru the system to the taps in the boat. We put in a new all-SS heater in the 90's and never have had the problem again.
    BTW, when you put in a new tank, there is really no need to go to the hassle of a deck fill. Our came with fills on top of each tank, under the settees, and we just bring in the hose with a shut-off valve on the end and fill the tank thru an inspection port. Never any worries about contamination from a bad O-ring, or leaks from a fill hose and deck plate.
    Best of luck, and fair winds to you.
    Nanaimo BC, eh? You cruise in a paradise! :)

  5. firehoser75


    Joined Oct 1, 2008
    148 posts, 3 likes
    Bavaria 36 Cruiser
    Ca Nanaimo, BC
    Thanks for the replies.
    We have thought about and used (before) bottled water, but like Roy, wanted to cut down on the storage and garbage issue. Fast, changing the water tank would require MAJOR surgery. There is no way to get it out without removing a large section of the cabin floor (unfortunately). If I had a choice with this boat, I would not have had aluminum tanks, especially for fresh water. The reason I "prefilter" to remove chlorine is because of the aluminum tanks. I have read that bleach and or even the normal chlorine used in most municipal water supplies will slowly damage the aluminum and is what causes the white gritty "stuff" that can plug up the boat's water system. Luckily, no sign of these problems. I have one of those "endoscope" type of devices and have looked inside my water tank and it looks pretty clean with little to no sign of the "white stuff". The filter at the galley sink is quite expensive (cartridges are about $90 US) and is supposed to remove most things (including aluminum particles). It came with the boat. We have only used this new to us boat for one full season and have not noticed any (major) problems with the water system (like visible problems: cloudy or odd colours, or smells), but it is probably easier to prevent things like algae growth than it would be to remove it after the fact, hence my question. During the late spring and summer, we cruise for about 3 months (in a row) with most of the time away from the docks. We do shower on board, or we could make our water last longer if we had to. I am fussy about where I fill up the water as well.
    Yes, Fast, we do get to cruise in a paradise!! We feel very fortunate indeed.
    Thanks again,

  6. David in Sandusky

    David in Sandusky

    Joined Nov 8, 2007
    1,064 posts, 141 likes
    Hunter 27_75-84
    US Sandusky Harbor Marina, Lake Erie
    1. We follow Peggy Hall’s book (available on this site.)
    2. We fill our aluminum water tank with regular (chlorinated) water, and use it for everything including drinking. We carry water bottles for biking ashore, or convenience.
    3. We don’t use any filters.

    Chlorine from our city (marina) water seems to do a decent job of maintaining our system bug free after our spring “shock” treatment with diluted chlorine per Peggy’s instructions. And I see no signs of deterioration of our tank over the last 18 years. ( Years 23 through 41 for the boat.)

    Hunters aluminum tanks probably lasted longer than their planned lifetime for our boats. ( Who knew ours would still be going 100% after 41 years!) Aluminum seems to last well in fresh water, and have more problems after 20-30 years in a salt water environment. My idea is to use them until they leak, then replace with Roto-molded plastic from Ronco.

    plenny7 likes this.
  7. JamesG161


    Joined Feb 14, 2014
    2,904 posts, 844 likes
    Hunter 430
    US Waveland, MS
    I lived in Mexico for several years in early 1990's. We had to worry about what we drank, not cooking or bathing.

    My boat has one Aluminum and one "plastic" [160 gal total]. I prefer the Aluminum one. Why? Durability!

    Since I don't live on the seas, but use them for relaxing highways, drinking water has not been a limitation or worry. I do have a small bottle of water sanitation drops in my "ditch bag" for emergencies.

    Once sanitized, what is your source of bacterial contamination? Plus, what organics will the bacteria live on?

    Mexico had/has water treatment. The problem then was old piping, "quick" system repair and inconsistent treatment. From your description, you have none of Mexico's old problems.
    You can check out Back Packer's stuff, that uses "ultra filtration" which filters everything [bacterial ] from water for just drinking.

    I would think, what you are doing is sufficient protection.

    PS: There a many discussions on this subject in SBO forae.

  8. thinwater


    Joined Mar 26, 2011
    1,948 posts, 368 likes
    Corsair F-24 MK I
    US Deale, MD
    The Thetford product is based on benzalkonium chloride, common in hand sanitizers (and also pool algae treatment if you want it cheaper). It used in food processing to sanitize equipment, though there is some controversy over effectiveness and allowable limits in drinking water. I don't know.

    The typical hose filter is only rated to remove about 1/3 of the chlorine at normal flow rates. Yup, look it up. I've tested this. The rules only require 1/3 removal to be NSF rates for chlorine reduction.

    Search, but I have not found a water treatment that is both EPA rated and safe for aluminum. Bleach causes corrosion, hydrogen peroxide is not rated as effective at any safe concentration, and benzalkonium chloride is ONLY for surface sanitizing and must be flushed out (toxic). A conundrum.

    AquaMega tabs and CLeantabs are MUCH less corrosive to aluminum due to an inhibitor. I think these are the best bet for aluminum tanks.

  9. Capt Robbie

    Capt Robbie

    Joined Jan 24, 2017
    256 posts, 90 likes
    Hunter 34
    Us Red Bank NJ
    I only use bottled water for drinking on the boat even though the tank water is safe to drink and filtered, wife says that tank water has plastic taste to it, I can't taste anything. :deadhorse:
    Happy wife happy life

    We basically just use the tank water for showers and cleaning.
    I also add about 3 oz of chlorine per 30 gallon tank to keep bacteria in check, it's good for about a week. We go through about a tank of water per weekend so the water never really gets stagnant.

    I agree with previous posts about drinking bottled water instead of tank water. Just no worth spending my weekend in the head, I rather be sailing :) ⛵️

    I don't have aluminum tanks, however I don't know why you can't add a few oz of chlorine to them for the sanitation of the water. Not sure if I would want to drink or use water that has been setting in a tank for more than a few weeks. Kinda be afraid of bacteria in the water.

    Now in response to the space that the empty bottles take up.
    Loosen the cap , crush the bottle, re-seal the cap. Take up a quarter of the space in the trash.

  10. JamesG161


    Joined Feb 14, 2014
    2,904 posts, 844 likes
    Hunter 430
    US Waveland, MS
    Did you use a White RV type water hose to fill your tank?

  11. firehoser75


    Joined Oct 1, 2008
    148 posts, 3 likes
    Bavaria 36 Cruiser
    Ca Nanaimo, BC
    Thinwater (and others),
    Thanks for the info. I did not know that charcoal filters only removed 1/3 of the chlorine from the water. I am not finding it easy to find a source (preferably local) for the AquaMega Tabs or the CleanTabs. It seems they are British products and for Canadians not only are shipping costs high (for any international), but the couriers sock it to us again with high "brokerage fees" as they call them, making it sometimes crazy expensive to ship (sometimes as much (or more for inexpensive items) as the item(s) purchased). I will also look for other products that contain the same active ingredients.
    For those who have commented on adding bleach to water in aluminum tanks, according to my research, not a good idea at all! Even the residual chlorine in "city water" will attack the aluminum (and welds) leading to leaks in the long term, and it causes the formation of a white crystal like substance that will clog filters, aeriators, etc. in the shorter term. If I remember correctly, even Peggy Hall advised against bleach in aluminum tanks. Last summer, other than cleaning and sanitizing my water system with the Thetford Water Sanitizer product, we prefiltered the water when filling up and used a Natures Pure QC2 filter (somewhat like the Seagull filter system) at the galley sink. We never noticed any odours, sediment, strange tastes, or discolouration. No one was sick at all. However, I agree that we don't want to chance it (the growth of bacteria and algae), hence my questions about safely treating the water stored in the tank (without damaging the tank). I don't believe there is any source of bacterial contamination or organic "food" sources in my system, my concern is only precautionary.
    Where we often travel, into very remote areas, getting rid of garbage is a real issue. I don't believe in (illegally) dumping, sinking, burying, or any other non-approved method of removal. As such we are often carrying 2-3 weeks worth of garbage before we go ashore where there are garbage facilities, so adding to this with crushed empty water containers would be difficult. In addition, finding storage for that many full containers is also a bit problematic (but probably not impossible). If we travelled where we were a week or less between provisioning and garbage stops, then the bottled water idea would make perfect sense.

    JamesG161 likes this.
  12. Gunni


    Joined Mar 16, 2010
    5,173 posts, 1,004 likes
    Beneteau 411 Oceanis
    US Annapolis
    Thin water, nice work on that study. Dichloroisocyanurate does look the best bet for for folks with aluminum water tanks. However I find all of these treatments tend to get overdosed and would always want to see a Point of Use to pull the treatment byproduct out of the water before consumption.

    Firehoser - granular charcoal filtration is capable of removing all residual chlorine from water. It is very effective until you reach saturation at which point your nose or a simple pool test kit can confirm time to replace your filte media. You can place two filters with a bypass and have a bulletproof solution. Prefiltration of your water is a fine thing but all you need is a leaky deck fill or some backwash through your tank vent and your tank is compromised. The SeaGull filter is a pretty effective filter but I wouldn’t want to hang my gut health on it alone.

  13. JamesG161


    Joined Feb 14, 2014
    2,904 posts, 844 likes
    Hunter 430
    US Waveland, MS
    I found this discussion with MaineSail, Gunni, Thinwater and many others about using a Carbon Filter to be fairly complete.

    I will never use Dichloroisocyanurate.:snooty:

    If I need to drink, I have so many alternatives.

    I did find the "hand notes" of the previous owner on his "bleach formula". I just chuckled a bit.
    I do use Bleach as a "anti venom" for stings of Jelly fish and more, and sometimes as a "head" cleaner.

    On my many "non-surviving" cruises, I like this summer time alternative.

    I brew tea, pour the boiled tea into sterilized plastic containers, freeze the tea, and put them in my Freezer on board.

    During a summer cruise, take out one of the 3 frozen tea bottles, and sip on "iced tea". The container can cool your body too.

    PS: In that link, I did list all of the "drinking water" treatment alternatives I could find.:pimp:

  14. FastOlson


    Joined Apr 8, 2010
    971 posts, 95 likes
    Ericson Yachts Olson 34
    US Portland OR
    Regarding reply #9, and the mention of "tank taste"... this is a real but thankfully rare problem.
    Several decades ago I added a second water tank to our prior boat. Bought from a trusted vendor, and molded out by Krakor (IIRC), it should have been fine. It was not. There was a persistent and noticeable taste and smell of "plastic", and no amount of washing it out with soaps or bleach or anything else, including whatever the seller suggested, would make that taste go away.
    I called them a last time about a year later and they said they would replace it. So I swapped it for another new one, and no more taste problem at all.
    They told me that sometimes, when the tank is being rotomolded, the temperature is too hot by a degree or three and the material gets 'over cooked'. Once this happens, nothing can change it back.

    My guess is that new tanks that flunk QC get ground up and recycled somehow, but no chemist am I.
    So, the takeaway is that if you ever find yourself with such a tank, just call Ronco for a replacement. Plan 'B' is to find a shop that builds tanks to your exact specs by welding the plastic panels together with 'hot air welding'. Our present boat needed a custom water tank, and there was (astoundingly...) nothing quite right in the Ronco catalogue. :)
    So I tracked down a guy locally that did this type of construction and got a perfect tank. No odd taste, either.

    Multi faceted problem, sometimes. But fixable.

    Having clean drinking water when we out cruising, right out of the tap, is worth some work and planning, IMHO.

    Further, the advice (reply 10) to use a hose specified for potable water is important, too. Our last replacement hose was on sale @ Camping World. (They have quite a few things suitable for our 'floating RV'...)

Gray Enterprises port gasket
Stop winter leaks. Compare our price!
Low prices, custom fit, no-wait estimates
Leaky Lewmar ports?
Start by replacing lens gaskets in stock now
Sunbrella lifesling covers
Any color, fits over existing bag to match your existing canvas.