drinking water from holding tanks

[thinwater]

That makes perfect sense. Our tanks have only been "used" for ten years at the most, so they should be good for some time yet.

We filter all water on the way in with a carbon filter so there should be little or no chlorine. We also find that the filter removes the smell and taste from the plastic water lines used at most marinas.

So far, so good. We do use your process every spring plus ensure the tank contents are turned over at least biweekly.

Chris

If you check the actual specifications of the carbon filter you will find that it probably reduces the chlorine about 50-25%, if flowed at the rated capacity. However, during filling, you are probably filling at twice that rate. In testing, hose-end filter reduce the chlorine 8-22%. You can check this by getting pet store aquarium strips and measuring before/after.

So yeah, it's kind of false advertising.

 

[thinwater]

Is the bleach method safe for aluminum tanks?
Our tanks have a few "pock narks", one of which was an actual leak. The leak was repaired (plate welded over it) and we use the tanks daily.
While bleach is corrosive, would exposure to a relatively weak solution once a year for a few hours be an issue? Or should people with aluminum tanks be using a different chemical?

Chris

Sodium dichlorisocyanurinate (Aqua Mega tabs, and perhaps others) has been studied by WHO and EPA for disinfecting drinking water. It is non-corrosive to aluminum tanks. It's sanitizing properties are basically identical to bleach (the active species in solution are the same--the organic acid is there to increase stability and inhibit aluminum corrosion), except the residual lasts for weeks instead of hours (through it can be eliminated quickly with a carbon filter). Perfect for sanitizing aluminum tanks. And easy, off-the-shelf solution that has tested safe. Why guess?

Don't believe me--Google it. You can do your own corrosion testing, or you can read Practical Sailor.