Resolution
Well-known member
Depends on which single malt you are offering.
Cleaning Fresh Water Tank
- Thread starter matthewriches
- Start date
thinwater
Well-known member
I did a bunch of testing on effectivness and corrosion for Practical Sailor. Included was Puriclean (sodium dichloroisocyanurate).
Further investigation would have revealed that isocyanurate is used as a chlorine stabilizer for swimming pools, resulting in 2 interesting differences from bleach:
* Much longer chlorine life span in the water. This is the primary reason for greater effectiveness.
* Much lower corrosion rates on aluminum (I did not investigate stainless). The isocyanurate has an inhibiting effect, slowing corrosion ~ 10-100 times.
Sodium dichloroisocyanurate has many water treatment approvals.
Good product. They also make tablets for regular use. More expensive than bleach, but very handy and effective.
----
Do remember that with bleach, more is not better. More increases the pH, making the bleach actually less effective and of course, increasing rinse times.
As for sanitizing, the US has the following standard:
The RV code (ANSI A119.2 section 10.8) has a standard procedure that is oft quoted and works very well. We’ve added a few details, but the bones of it come straight from the code and have been reviewed and accepted by the US Public Health Service.
1. Turn off the hot water heater until finished.
2. Remove any carbon canisters or micron rated filters. Remove any faucet aerator screens. Wire mesh pump protection strainers should stay in place. The plumbing will very likely slough off a layer of bacteria during later flushing steps.
3. Clean and remove the vent screen and flush the vent hose.
4. Use the following methods to determine the amount of common household bleach needed to sanitize the tank.
1. A) Multiply “gallons of tank capacity” by 0.13; the result is the ounces of bleach needed to sanitize
the tank. This is 1/8 cup of plain bleach (no fragrance) per 10 gallons.
1. B) Multiply “Liters of tank capacity” by 1.0; the result is the milliliters of bleach needed to sanitize the
tank.
5. Mix the proper amount of bleach within a 1-gallon container of water. This will provide better mixing and reduce spot corrosion of aluminum tanks.
6. Pour the solution (water/bleach) into the tank and fill the tank with potable water.
7. Allow some solution to escape though the vent, if safe and applicable (some boats use the vent as an over flow, while in some cases the vent is in the interior). This will sanitize the vent line.
8. Open ALL faucets (hot and cold) allowing the water to run until all air is purged and the distinct odor of chlorine is detected. Leave the pressure pump on.
9. The standard solution must have four (4) hours of contact time to disinfect completely. Doubling the solution concentration allows for contact time of one (1) hour.
10. When the contact time is completed, drain the tank. Refill with potable water and purge the plumbing of all sanitizing solution. Repeat until bleach is no longer detectable.
11. If the smell of bleach persists after two refill and drain cycles, add a teaspoon of hydrogen peroxide per 20 gallons and mix. The peroxide will oxidize the hypochlorite to chloride (salt) and oxygen, neutralizing the bleach. Any excess peroxide will be harmless to drink and will have no taste. Peroxides are common ingredients in commercially available water freshening preparations. Others suggest vinegar, but vinegar at long dilutions can ferment, undoing all of your hard work.
12. Replace all filters and the vent screen.
Further investigation would have revealed that isocyanurate is used as a chlorine stabilizer for swimming pools, resulting in 2 interesting differences from bleach:
* Much longer chlorine life span in the water. This is the primary reason for greater effectiveness.
* Much lower corrosion rates on aluminum (I did not investigate stainless). The isocyanurate has an inhibiting effect, slowing corrosion ~ 10-100 times.
Sodium dichloroisocyanurate has many water treatment approvals.
Good product. They also make tablets for regular use. More expensive than bleach, but very handy and effective.
----
Do remember that with bleach, more is not better. More increases the pH, making the bleach actually less effective and of course, increasing rinse times.
As for sanitizing, the US has the following standard:
The RV code (ANSI A119.2 section 10.8) has a standard procedure that is oft quoted and works very well. We’ve added a few details, but the bones of it come straight from the code and have been reviewed and accepted by the US Public Health Service.
1. Turn off the hot water heater until finished.
2. Remove any carbon canisters or micron rated filters. Remove any faucet aerator screens. Wire mesh pump protection strainers should stay in place. The plumbing will very likely slough off a layer of bacteria during later flushing steps.
3. Clean and remove the vent screen and flush the vent hose.
4. Use the following methods to determine the amount of common household bleach needed to sanitize the tank.
1. A) Multiply “gallons of tank capacity” by 0.13; the result is the ounces of bleach needed to sanitize
the tank. This is 1/8 cup of plain bleach (no fragrance) per 10 gallons.
1. B) Multiply “Liters of tank capacity” by 1.0; the result is the milliliters of bleach needed to sanitize the
tank.
5. Mix the proper amount of bleach within a 1-gallon container of water. This will provide better mixing and reduce spot corrosion of aluminum tanks.
6. Pour the solution (water/bleach) into the tank and fill the tank with potable water.
7. Allow some solution to escape though the vent, if safe and applicable (some boats use the vent as an over flow, while in some cases the vent is in the interior). This will sanitize the vent line.
8. Open ALL faucets (hot and cold) allowing the water to run until all air is purged and the distinct odor of chlorine is detected. Leave the pressure pump on.
9. The standard solution must have four (4) hours of contact time to disinfect completely. Doubling the solution concentration allows for contact time of one (1) hour.
10. When the contact time is completed, drain the tank. Refill with potable water and purge the plumbing of all sanitizing solution. Repeat until bleach is no longer detectable.
11. If the smell of bleach persists after two refill and drain cycles, add a teaspoon of hydrogen peroxide per 20 gallons and mix. The peroxide will oxidize the hypochlorite to chloride (salt) and oxygen, neutralizing the bleach. Any excess peroxide will be harmless to drink and will have no taste. Peroxides are common ingredients in commercially available water freshening preparations. Others suggest vinegar, but vinegar at long dilutions can ferment, undoing all of your hard work.
12. Replace all filters and the vent screen.
Last edited:
nigelmercier
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I get through about 5kg of this per year in my pool, in this market it is known as Stabilised Chlorine.
You do pay the "Pool Tax" but probably less than the "Marine Tax"
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vyv_cox
Well-known member
I was (and remain) rather puzzled in the context of drinking water disinfection by your reference to strong chloride solution attack on stainless steel but wonder - especially after your response - if I was (or am) missing something?
Most stainless steels, but 300 series in particular, have problems with chlorides. Pitting/crevice corrosion is the first problem, partly alleviated in 316 by molybdenum additions. But stress corrosion cracking is maybe the greater problem. The stress may be internal, due to cold work during manufacture, or external due to the duty. I have several shackles and connectors that failed due to SCC despite having low hardness (and therefore internal stress) Much stainless steel sheet, such as might be used for tank manufacture, is cold rolled.
Hydrozoan
Well-known member
Thanks Vyv, but my post at #29 was dealing with chlorine as I emphasizied - not with chloride ion, which is essentially irrelevant to disinfection.
NormanE at #19 referred specifically to damage to SS from chlorine disinfection, to which the Nickel Institute text I quoted at #29 applies. The ppm levels of free chlorine to which it refers are I believe relevant to disinfection and shock cleaning by Milton, bleach etc. and not in a ‘different league’ of chlorine dosing as you suggested at #35.
Thanks also to thinwater for Post #42 - interesting.
vyv_cox
Well-known member
My post #29 was a comment on the difference between the use of chlorine gas and a hypochlorite solution sold by every pharmacist.
VicS
Well-known member
chrishscorp
Well-known member
Previous owner had ripped down forecabin headlining, dust, filth, glue, fibreglass and mould everywhere, drinking water tank open to all of that. I think i may have overdosed it slightly
I wanted to know i could fill it up and drink from it safely, it only has a slight taint when left to stand for several weeks, in regular use weekend/ week long use its not noticed. Bottled water available for the sensitive types ........
vyv_cox
Well-known member
If I remember correctly (it's a long time since babies' bottles were part of my life) the Milton packaging says that it is safe not to rinse the product out before filling with milk for the baby. For beer making, a later activity in my life, I think the same applies.
chrishscorp
Well-known member
Fantasie 19
Well-known member
brewing beer in the water tank on board..... now there is an idea
...especially in the Med or other warmer climes....
Hydrozoan
Well-known member
The Nickel Institute text which I quoted and linked (at #29 - that was my post, I think) refers to 'chlorine dosing', but the paper linked to immediately below the text (see the direct link below) discusses the various sources of disinfection 'chlorine': chlorine gas, sodium hypochlorite and calcium hypochlorite (chemically there is little difference). It goes on to discuss the effects of disinfection levels of chlorine on various stainless steels (and on other alloys). There is quite a lot of information in it about the resistance of various grades of SS to disinfection levels of free chlorine, which is germane to this discussion.
https://www.nickelinstitute.org/~/m...rineonCommonMaterialsinFreshWater_14049_.ashx
Last edited:
MikeBz
Well-known member
Thread resurrection... the general advice when using the cheap supermarket bleach option is to leave it for 12-24 hours and then flush/rinse. Out of curiosity why should you not bung the bleach in when you lay up and flush it out (perhaps with another bleach cycle) in the spring?
VicS
Well-known member
You might prefer to drain the fresh water system when laying up as a precaution against the effects of freezing
I drain my tank when laying up and dose the water with the recommended quantity of Milton when refilling the following year, although I usually do pump a little of a more concentrated solution through the pipework first.
RichardS
N/A
In effect, that's what I do whenever I leave the boat for more than a few weeks, by chucking a water sterilisating tablet into both water tanks before I leave. Even if I've drained the tanks by leaving a tap running there is always a cm or so depth of water in the bottom so the fizzing bleach pill kills any bugs in there.
Richard
MikeBz
Well-known member
That's a fair point. Perhaps I'll dose/leave/drain and then dose& flush again just before launch.
ghostlymoron
Well-known member
When I inspected Anemone's water tanks, which are grp formed partly by the hull, it was surprisingly clean. Only a few white nodules on the underside of the top which removed quite easily with a stuff brush.
Its very unlikely there would be any algal growth in the absence of light. In the water industry we use mainly chlorine as disinfectant, either gaseous or hypochlorite. For disinfecting repairs etc domestic bleach is commonly used, I once flushed a whole bottle of Brobat into the supply to Stoke on Trent during a night shutdown. There were no complaints, surprisingly.
On Anemone, I disinfected with Domestos although own brand would be cheaper, about half a bottle, left overnight then flushed with fresh water three times. The smell of chlorine is very persistent but soon evaporates from an open container. I never felt it necessary to use bottled water as I have confidence in the public water supply (in the UK) to which standards apply (unlike commercial bottled water).
Its very unlikely there would be any algal growth in the absence of light. In the water industry we use mainly chlorine as disinfectant, either gaseous or hypochlorite. For disinfecting repairs etc domestic bleach is commonly used, I once flushed a whole bottle of Brobat into the supply to Stoke on Trent during a night shutdown. There were no complaints, surprisingly.
On Anemone, I disinfected with Domestos although own brand would be cheaper, about half a bottle, left overnight then flushed with fresh water three times. The smell of chlorine is very persistent but soon evaporates from an open container. I never felt it necessary to use bottled water as I have confidence in the public water supply (in the UK) to which standards apply (unlike commercial bottled water).
ghostlymoron
Well-known member
If you didn't have see through polycarbonate, you probably wouldn't get any 'green stuff'.
ghostlymoron
Well-known member
I'd be a bit wary of leaving strong chlorine in the state for a prolonged period. It might 'impregnate' any rubber or plastic components and be impossible to flush out.
Hydrozoan
Well-known member
+1