Water Tanks

[mbaker]

Both tanks corroding from inside,
aluminum flacks in filters. Replacing tanks almost impossible unless we tear apart the boat. thinking to cut access ports in tanks, cleaning and sealing. Thoughts and ideas???

 

[ggrizzard]

If you can cut an access hole in the top of the tank(s), you could install a flexible bladder tank(s). Save yourself a lot of grief.

 

[RoyS]

You may be able to cut the access holes and then paint the inside with some kind of sealer suitable for drinking water. The original aluminum will be strong enough to support the water, only porous. The sealer will seal the pin holes. Sorry I have not researched enough to identify a sealer but I am sure there are such products available.

 

[MikeHoncho]

I had a leak in my 40 gallon aluminum tank at a weld. To replace or remove would mean cutting up the fiberglass cabinet. I cut a 4x4 inch hole in in over the leak. I found the expected.....calcification deposits all over the inside of the tank with pitting. I considered coating the inside with some sort of product but the deposits would have made it very difficult being they would have to be ground off. I ground down the area leaking, cleaned it with solvent and sealed the area with 5200. I make a cover out of plate aluminum and sealant, securing it with self tappers. I do not ever plan on using the tank water for consumption while the tank and current plumbing is in there. We use the system for dish washing, showers and washing hands. It has held for 1/5 years. I just replaced my fuel tank. The new tank came with a gauge sending unit that I had to replace due to not having a return for the diesel engines. I'm going to mount it in the tank also for a level gauge. Again, the water in the system is not for consumption its for convenience.

 

[jviss]

While it's only slightly more active than aluminum, would a magnesium anode protect a drinking water tank?

 

[MikeHoncho]

The research I came up with seemed to point to bleach being a main contributor to the deposits. Water heaters have anodes in them. I would expect those would be just as effective in a water tank.

 

[Jim_H42]

I'm aware that the port mid-ship tank on a P42 is replaceable relatively easily. That is what I'll do to once mine starts leaking. The v-berth tank is another story from I've heard/seen.

Eianm, on this site has documented his fix for the forward tank here:
Hunter 42 Owner Modifications and Upgrades

And there is someone in the Facebook Hunter Passage Sailboats group currently doing the midship tank. You might check out those pictures.

 

[mbaker]

Thanks for all the thoughts. I've started the project by removing the cabin sole above the mid-ship tank. The fiberglass upright support for the settee had to be removed and the base of the stairs where the compressors are for frig and freezer. Loosen the backboard for the water tank valves and cut electric wire for under seat lighting. To remove the tank , the locker next to the chart table would have to be disassembled and the
frig & freezer compressors disconnected and moved..... not going to happen. The tank would need to be cut into pieces to be removed and a smaller tank put in its place. The fill and vent hoses are in the base of this locker.
Going with option B. Cut inspection hole on top of tank in forward, starboard quadrant. This is the low point in tank and where the pick-up tube is located. As expected, at least an inch of metal flakes, dirt and debris. The tank itself seems to be in relatively decent shape. I will cut three more access ports in the other quads. and begin the cleanup and sealing process.
More to come.....

 

[JamesG161]

Aluminum tanks are attacked by Chlorine in city drinking water.
The white flakes are [non toxic] Aluminum Chloride [AlCl3].

The weld areas are the classic spots for the attack.
You can remove AlCl3 from your tank with Alcohol.[ cheap vodka]

Bleach contains concentrated Chlorine.

I use Hydrogen Peroxide to sanitize my Aluminum tank.
_____
Sealing with 5200 should work.

Jim...

PS: This is not Galvanic corrosion so anodes don't work.

 

[jviss]

I fill my tanks (usually) at my marina, which supplies well water. I don't think it's chlorinated. But, I have found aluminum flakes; maybe from the previous owner's use? Tank is 23 years old. What should I do?

 

[MikeHoncho]

Anyone had experience with installing bladders in a existing tank? Seams pretty involved considering you have to deal with the fill inlet, draw outlet and a vent.

 

[JamesG161]

I fill my tanks (usually) at my marina, which supplies well water. I don't think it's chlorinated.

It is very rare that any USA public drinking water is without some form of Sanitation [ commonly Chlorination]. Private ownership does not exempt this. A swimming pool test kit can confirm Chlorination or perhaps ask the well owner.

Normally AlCl3 white flakes[non toxic] are found on the tank bottom welds and with most on the corners.

You can remove most dissolved Chlorine, from water, with Carbon fiber filters before going in your water tanks.

Also some public waters contain Sulfates which can form Al2(SO4)3 Aluminum Sulfate.

Note: If these reaction products are left alone, they will form a "Scab" and significantly reduce further reactions.

I would suggest leave the AlCl3 alone and put a fine mesh strainer in your water supply pump suction.
Jim...

PS: Dissolved Chlorine gas will disappear after a day, if opened to atmospheric pressure. My water tanks are open through their vents.

 

[jssailem]

I fill my tanks (usually) at my marina, which supplies well water. I don't think it's chlorinated.

So you really have no idea what is in the water.

​

The Massachusetts Department of Environmental Protection (MassDEP) recommends:​

If you have a private well, then water quality testing should be important to you and your family.​

Some contaminants in drinking water have been linked to cancer and toxicity, posing a risk to human health. Many contaminants often have no taste, odor, or color. Only laboratory testing can detect them.​

While there is no state requirement to have your well water tested (although there may be from local Board of Health), the Massachusetts Department of Environmental Protection (MassDEP) recommends that all homeowners with private wells do so, and use a state certified laboratory.​

Protect Your Family: A Guide to Water Quality Testing for Private Wells

If you have a private well, then water quality testing should be important to you and your family.

www.mass.gov

 

[jviss]

So you really have no idea what is in the water.

​

The Massachusetts Department of Environmental Protection (MassDEP) recommends:​

If you have a private well, then water quality testing should be important to you and your family.​

Some contaminants in drinking water have been linked to cancer and toxicity, posing a risk to human health. Many contaminants often have no taste, odor, or color. Only laboratory testing can detect them.​

While there is no state requirement to have your well water tested (although there may be from local Board of Health), the Massachusetts Department of Environmental Protection (MassDEP) recommends that all homeowners with private wells do so, and use a state certified laboratory.​

Protect Your Family: A Guide to Water Quality Testing for Private Wells

If you have a private well, then water quality testing should be important to you and your family.

www.mass.gov

Why do you assume they don't have it tested???

 

[RoyS]

Regarding aluminum corrosion leading to tank perforation. My 39 year old tank is still without leaks, however, the aluminum pickup tube became perforated a few years ago and had to be addressed. Close examination after a 6" clean-out port was installed in the tank top revealed that the pickup tube suffered more corrosion damage near the bottom than at the top. This undoubtedly is because the tank water level is often below the very top. I cut the tube off about two inches from the top and sleeved it with a vinyl hose that reached the tank bottom. The aluminum tube was corroded from both the inside and the outside so it is no surprise that it failed before the tank which has water contact only on the inside. In addition, the tank aluminum is thicker than the pickup tube. I suspect that your first sign of trouble will be your pickup tube drawing air as well as water. It can be fixed simply and that repair may be all that you need. It is also beneficial to use the clean-out to completely dry the tank bottom for winter storage.

 

[jviss]

Regarding aluminum corrosion leading to tank perforation. My 39 year old tank is still without leaks, however, the aluminum pickup tube became perforated a few years ago and had to be addressed. Close examination after a 6" clean-out port was installed in the tank top revealed that the pickup tube suffered more corrosion damage near the bottom than at the top. This undoubtedly is because the tank water level is often below the very top. I cut the tube off about two inches from the top and sleeved it with a vinyl hose that reached the tank bottom. The aluminum tube was corroded from both the inside and the outside so it is no surprise that it failed before the tank which has water contact only on the inside. In addition, the tank aluminum is thicker than the pickup tube. I suspect that your first sign of trouble will be your pickup tube drawing air as well as water. It can be fixed simply and that repair may be all that you need. It is also beneficial to use the clean-out to completely dry the tank bottom for winter storage.

That's very , very interesting, for this reason: could it be that the aluminum pickup tube is of an alloy that is less noble, i.e., more anodic, than the aluminum of the tank, ad therefore by corroding first is protecting the tank?

 

[RoyS]

Jviss, I have no idea about the alloys in either the tank or the pick-up tube. The tube was thinner than the tank walls and the tube had water on both the inside and the outside. Regardless, if the tank shows signs of leaking in the future I plan to use the access port plus a second access port to coat the inside with some non-toxic sealant. The second access port would be required due to a center baffle. Based on my experience here, the corrosion would be mostly near the bottom which would be easy to seal from the access ports, perhaps with a paint roller. Far easier to do that than to replace the fiberglass enclosed tank itself.

 

[JamesG161]

Corrosion is enhanced on entrance and exits of tanks from turbulence.

Fill you tank through this filter or similar.
DuPont WFPF13003B Universal Whole House 15, 000-Gallon Water Filtration System - Faucet Mount Water Filters - Amazon.com
Using these cartridges.
DuPont WFPFC8002 Universal Whole House Carbon Wrap 2-Phase Cartridge, 2-Pack - Replacement Water Filters - Amazon.com

Rigging them for a hose is easy.
____
You did note that both sides of the tube is exposed.

Note: The surface area of Aluminum exposed to Chlorine is large for tank wall, thus slow loss overall.

Jim...

 

[Justin_NSA]

If I had an AL freshwater tank I think I'd have a filter under the sink. My tank is plastic. I just have to worry about BPAs

Tips to reduce BPA exposure

Find out more about BPA, a chemical used in some plastics and resins, and explore options for reducing your exposure.

www.mayoclinic.org

 

[JamesG161]

My tank is plastic

To remove BPA, you can use the filter or smaller in my post #18 above.
or any carbon active filter.
Jim...