Hello all, I have been told to add a small amount of bleach when filling the water tanks to help keep the bugs at bay. Anyone know the right amount per gallon which is safe. We don't drink our tank water, but want to keep it at a safe level just in case someone does. Thanks Gary
Adding Bleach to Water Tanks
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If you're using known good city water you don't need to add anything to it. It's already been chlorinated.
I don't know the "right amount" but when I was filling my tanks from a residential well (my home and I drank it), I would use a teaspoon or so for twenty gallons.
Unless your tanks are empty it's difficult to know how much water you are adding so it's difficult to say how much bleach to add. I'll just add a teaspoon or so if I'm somewhere where the water is questionable. Or, I'll wait and fill the tanks somewhere else.
I don't understand why people are reluctant to drink the water from their boat. Using good water to start with and a dedicated drinking water safe hose to fill the tanks, this should be just fine to drink. My wife and I have been drinking the boat's water for years.
psneeld
Guru
Drinking boat water can make one grouchy and opinionated.
Maybe if that's ALL you drink aboard...
Pretty sure someone posted awhile back about the life expectancy of chlorine in water. If true and I have no doubt about who posted it, then a small maintenance amount may be necessary if you don't use your water fast enough.
Peggie Hall, best known for her advice on marine sanitation systems (she ran such a company for many years) offers this advice about potable water systems:
"Although most people think only in terms of the tank, the plumbing is
actually the source of most foul water, because the molds, mildew, fungi
and bacteria which cause it thrive in damp dark places, not under water.
Many people—and even some boat manufacturers—believe that keeping the
tanks empty reduce the problem, but an empty water tank only provides
another damp dark home for those “critters.”
"There are all kinds of products sold that claim to keep onboard water
fresh, but all that’s really necessary is an annua--or in especially
warm climates, semi-annual recommissioning of the entire system-—tank
and plumbing. The following recommendations conform to section 10.8 in
the A-1 192 code covering electrical, plumbing, and heating of
recreational vehicles (including boats). The solution is approved and
recommended by competent health officials. It may be used in a new
system a used one that has not been used for a period of time, or one
that may have been contaminated.
"Before beginning, turn off hot water heater at the breaker; do not turn
it on again until the entire recommissioning is complete.
1. Prepare a chlorine solution using one gallon of water and 1/2 cup (4
oz) Clorox or Purex household bleach (5-7% sodium Hypochlorine
solution). With tank empty, pour chlorine solution into tank. Use one
gallon of solution for each 5 gallons of tank capacity.
2. Complete filling of tank with fresh water. Open each faucet and drain
cock until air has been released and the entire system is filled. Do
not turn off the pump; it must remain on to keep the system pressurized
and the solution in the lines.
3. Allow to stand for at least three hours, but no longer than 24 hours.
4 Drain through every faucet on the boat (and if you haven't done this
in a while, it's a good idea to remove any diffusion screens from the
faucets, because what's likely to come out will clog them). Fill the
tank again with fresh water only, drain again through every faucet on
the boat.
5. To remove excess chlorine taste or odor which might remain, prepare a
solution of one quart white vinegar to five gallons water and allow this
solution to agitate in tank for several days by vehicle motion.
6. Drain tank again through every faucet, and flush the lines again by
fill the tank 1/4-1/2 full and again flushing with potable water.
"People have expressed concern about using this method to recommission
aluminum tanks. While bleach (chlorine) IS corrosive, it’s effects are
are cumulative. So the effect of an annual or semi-annual "shock
treatment" is negligible compared to the cumulative effect of holding
chlorinated city water in the tank for years. Nevertheless, it's a good
idea to mix the total amount of bleach in a few gallons of water before
putting it into either a stainless or aluminum tank."
Before you ask...For regular annual recommissioning, it prob'ly wouldn't
be necessary to completely fill a 125 gallon tank if you use your water
and replace it often...since 90% of foul water problems originate in
the plumbing, 40-50 gallons should be enough in most cases. But since
yours has been unused for several years, I think you'd better fill it
completely...'cuz the same "critters" that grow in damp dark lines are
also likely to have taken up housekeeping in a tank.
That chapter includes some additional things you can do keep your fresh
water fresher longer, btw.
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/html/get_rid_of_boat_odors.html
"Although most people think only in terms of the tank, the plumbing is
actually the source of most foul water, because the molds, mildew, fungi
and bacteria which cause it thrive in damp dark places, not under water.
Many people—and even some boat manufacturers—believe that keeping the
tanks empty reduce the problem, but an empty water tank only provides
another damp dark home for those “critters.”
"There are all kinds of products sold that claim to keep onboard water
fresh, but all that’s really necessary is an annua--or in especially
warm climates, semi-annual recommissioning of the entire system-—tank
and plumbing. The following recommendations conform to section 10.8 in
the A-1 192 code covering electrical, plumbing, and heating of
recreational vehicles (including boats). The solution is approved and
recommended by competent health officials. It may be used in a new
system a used one that has not been used for a period of time, or one
that may have been contaminated.
"Before beginning, turn off hot water heater at the breaker; do not turn
it on again until the entire recommissioning is complete.
1. Prepare a chlorine solution using one gallon of water and 1/2 cup (4
oz) Clorox or Purex household bleach (5-7% sodium Hypochlorine
solution). With tank empty, pour chlorine solution into tank. Use one
gallon of solution for each 5 gallons of tank capacity.
2. Complete filling of tank with fresh water. Open each faucet and drain
cock until air has been released and the entire system is filled. Do
not turn off the pump; it must remain on to keep the system pressurized
and the solution in the lines.
3. Allow to stand for at least three hours, but no longer than 24 hours.
4 Drain through every faucet on the boat (and if you haven't done this
in a while, it's a good idea to remove any diffusion screens from the
faucets, because what's likely to come out will clog them). Fill the
tank again with fresh water only, drain again through every faucet on
the boat.
5. To remove excess chlorine taste or odor which might remain, prepare a
solution of one quart white vinegar to five gallons water and allow this
solution to agitate in tank for several days by vehicle motion.
6. Drain tank again through every faucet, and flush the lines again by
fill the tank 1/4-1/2 full and again flushing with potable water.
"People have expressed concern about using this method to recommission
aluminum tanks. While bleach (chlorine) IS corrosive, it’s effects are
are cumulative. So the effect of an annual or semi-annual "shock
treatment" is negligible compared to the cumulative effect of holding
chlorinated city water in the tank for years. Nevertheless, it's a good
idea to mix the total amount of bleach in a few gallons of water before
putting it into either a stainless or aluminum tank."
Before you ask...For regular annual recommissioning, it prob'ly wouldn't
be necessary to completely fill a 125 gallon tank if you use your water
and replace it often...since 90% of foul water problems originate in
the plumbing, 40-50 gallons should be enough in most cases. But since
yours has been unused for several years, I think you'd better fill it
completely...'cuz the same "critters" that grow in damp dark lines are
also likely to have taken up housekeeping in a tank.
That chapter includes some additional things you can do keep your fresh
water fresher longer, btw.
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/html/get_rid_of_boat_odors.html
knotheadcharters
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Two in-line filters and using city water, I drink the water on my boat. As far as the water tank underway, same thing. I do drain and refresh the water in my tank occasionally. I read somewhere that adding bleach can corrode your tank especially if it's aluminum.
re the Peggie Hall post, when I had a residential well and the pump had to be pulled for service or replacement, that was pretty much what we did to "purify" the well and water system afterwards. Pour a gallon of unscented bleach into the well, then run water through every outlet until we smelled bleach, let it sit overnight or a few hours, then run water until the smell was gone.
On EDIT: I read this wrong. I focused on one gallon of solution ignoring the key word solution. The word makes a difference.
[STRIKE]That seems like a HUGE amount of bleach for five gallons of water. To treat clear water only takes a few drops, or 1/8 of a teaspoon of bleach, per gallon of water. Maybe she had a typeo? [/STRIKE]
To clean containers, the CDC recommends four teaspoons per gallon.
http://www.cdc.gov/healthywater/pdf/emergency/09_202278-B_Make_Water_Safe_Flyer_508.pdf
A gallon has 768 teaspoons so a gallon of bleach which could treat 192 gallons of tanks and lines.
The CDC link also has the ratios for using bleach to make water safe to drink.
Later,
Dan
Last edited:
RT Firefly
Enigma
Greetings,
Our water tank has a history of laying fallow. We just haven't used the boat enough thus far. The one and only time I opened the tank I noticed what appeared to be algae on the sides. We do not use the water for drinking as of yet BUT in anticipation of an extended period aboard and potentially using the on board water for consumption, what I plan to do in the next month is:
Open the inspection port on the tank (aprox. 24" diameter)
Drain the tank with a sump pump (for speed and volume)
Wash down the walls and baffles with a pressure washer
Vacuum up any resultant "material"
Repeat if necessary
Spray down the walls and baffles with bleach (full strength)
Vacuum up residuals
Replace inspection port (temporarily)
Charge tank with Peggy's magic "elixer" (to the amount of 50 gallons or so)
Flood water lines and let stand
Re-drain tank from inspection port (sump pump)
Replace and seal inspection port
Fill tank (550 gallons)
Add bleach (amount to be calculated)
Final flush of water lines with "treated" (from the 550 gallons+bleach) water
I anticipate (hahahaha....There's that word again) it will take the better part of a day to complete.
Our water tank has a history of laying fallow. We just haven't used the boat enough thus far. The one and only time I opened the tank I noticed what appeared to be algae on the sides. We do not use the water for drinking as of yet BUT in anticipation of an extended period aboard and potentially using the on board water for consumption, what I plan to do in the next month is:
Open the inspection port on the tank (aprox. 24" diameter)
Drain the tank with a sump pump (for speed and volume)
Wash down the walls and baffles with a pressure washer
Vacuum up any resultant "material"
Repeat if necessary
Spray down the walls and baffles with bleach (full strength)
Vacuum up residuals
Replace inspection port (temporarily)
Charge tank with Peggy's magic "elixer" (to the amount of 50 gallons or so)
Flood water lines and let stand
Re-drain tank from inspection port (sump pump)
Replace and seal inspection port
Fill tank (550 gallons)
Add bleach (amount to be calculated)
Final flush of water lines with "treated" (from the 550 gallons+bleach) water
I anticipate (hahahaha....There's that word again) it will take the better part of a day to complete.
Last edited:
Capt.Bill11
Guru
Drinking boat water can make one grouchy and opinionated.
You just saved me years of therapy. Thanks!
Delta_JimS
Senior Member
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- 278
My 2 cents,
I just went through a similar bleach treatment.
I believe what Peggy was describing was what is known as a chlorine "shock" treatment, similar to what is commonly done to a backyard pool after your kids weekend pool party.
A much larger amount of bleach is added to "shock" the system.(critters) Somewhat like when the doctor tells you to take ALL of that antibiotic even if you feel better.
For the last several years I have just been adding a tablespoon of bleach to my tanks when I would fill them. The result was a chlorine smell that would last a couple of weeks and then a couple of weeks later that "stale" smell would come back.
I recently "shocked" my system with 2/3 cup of bleach, but forgot about leaving it for 3 hours and only did about an hour. I then flushed it with fresh water twice. The results are that I am almost up to 2 months now with fresh smelling water in the tanks after 2 partial refills. I am convined that Peggy's process is valid, though I may not use as much bleach and do the shock treatment more often than once a year if the stale smell comes back.
I just went through a similar bleach treatment.
I believe what Peggy was describing was what is known as a chlorine "shock" treatment, similar to what is commonly done to a backyard pool after your kids weekend pool party.
A much larger amount of bleach is added to "shock" the system.(critters) Somewhat like when the doctor tells you to take ALL of that antibiotic even if you feel better.
For the last several years I have just been adding a tablespoon of bleach to my tanks when I would fill them. The result was a chlorine smell that would last a couple of weeks and then a couple of weeks later that "stale" smell would come back.
I recently "shocked" my system with 2/3 cup of bleach, but forgot about leaving it for 3 hours and only did about an hour. I then flushed it with fresh water twice. The results are that I am almost up to 2 months now with fresh smelling water in the tanks after 2 partial refills. I am convined that Peggy's process is valid, though I may not use as much bleach and do the shock treatment more often than once a year if the stale smell comes back.
Ski in NC
Technical Guru
When my tank is low, I add a splash of bleach then run enough through each spigot to know the plumbing is filled. Let sit for a few hours to a day or so, then drain til pump ventilates. Then fill tank and clear lines. This works well. If I go for six months without doing this, I can detect stink in the water. Do "the treatment", all good again.
As I understand bleach, it is both concentration and contact time that disinfects. High concentration, kills fast. Low concentration kills slow, but still kills.
As I understand bleach, it is both concentration and contact time that disinfects. High concentration, kills fast. Low concentration kills slow, but still kills.
Been doing what she recommends for decades and always drink boat water. On this boat Ido have a carbon filter in the galley faucet .
Her point about being sure to treat all lines is critical. They are the first togo bad.
I have never figured out how to treat ice maker line though.
Her point about being sure to treat all lines is critical. They are the first togo bad.
I have never figured out how to treat ice maker line though.
hollywood8118
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Drinking boat water can make one grouchy and opinionated.
So you have been drinking boat water again?
HOLLYWOOD :lol:
hollywood8118
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hollywood8118
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Since we started cruising to suspect places we always added bleach to our water tanks.. I would rather have a little bleach in the system than all the growing stuff . We usually only drink from the galley which has a carbon filter that removes the bleach taste.. but I can taste a touch of it in the head while brushing teeth.. no biggie.
One big no no is to add bleach to the tanks if you have a water maker that uses tank (output) water to do its timed back flush cleaning cycles.. bleach KILLS water maker membranes
HOLLYWOOD
One big no no is to add bleach to the tanks if you have a water maker that uses tank (output) water to do its timed back flush cleaning cycles.. bleach KILLS water maker membranes
HOLLYWOOD
psneeld
Guru
plus I see in your avatar the bleach whitens your teeth....
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hollywood8118
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Over the 17 odd years I have had my two boats we have never traeted the tanks in any way, and happily drink the water.
I think we have SS tanks and we go through about 100 lites(approx 23 gallons) of water a day, so we fill the tanks every 10-14 days.
We have pretty good water on the whole in Sydney, so don't feel the necessity of treating the tanks.
I think we have SS tanks and we go through about 100 lites(approx 23 gallons) of water a day, so we fill the tanks every 10-14 days.
We have pretty good water on the whole in Sydney, so don't feel the necessity of treating the tanks.
CPseudonym
Moderator Emeritus
Andy, if your marina water is city water it is treating your system for you. Most municipal water systems are chlorinated and if you keep filling that frequently from a treated water source bacteria should never be an issue.
A more remote marina will likely be supplied with untreated well water. Not all well water is created equally due to a host of circumstances beyond your control. Couple that with reduced fill frequency and some boat tanks can become real science projects.
A more remote marina will likely be supplied with untreated well water. Not all well water is created equally due to a host of circumstances beyond your control. Couple that with reduced fill frequency and some boat tanks can become real science projects.
1950's/60's while growing up on boats I learned a strong shot of bleach in water tank at every other fill up is good to keep things in order. To this day I add bleach every other fill up. In 77 gallon tank-age I pour in about a cup o' bleach. Water looks sparkling clean with slight bleach smell; never have I "flushed-out" boat water tanks/system. Being that we do not live aboard... we bring ample drinking water aboard but do rinse food and brush teeth using tank water. Simple is as simple does!
PS: From taste while brushing teeth and clarity in a glass I feel drinking tank water would be OK. Good carbon filter on one tap should surely make even the slightest contamination a non-plus.
PS: From taste while brushing teeth and clarity in a glass I feel drinking tank water would be OK. Good carbon filter on one tap should surely make even the slightest contamination a non-plus.
Last edited:
ulysses
Guru
Chlorine within the system if maintained at 2 to 10 parts per million (which would be .2 -1 mg/l) will effectively eliminate most pathogens. Chlorine when exposed to air will gas out fairly quickly, thus using a hose to fill the tanks will deplete some of the Chlorine supplied with the municipal water. Rolling around in the tank will deplete some more. A swimming pool test strip will not even register such low amounts. Hach Company has a small test kit available. Remember that the household bleach is only about 6-7% chlorine if you do the math on the 2-10 ppm.
Waste of good bleach. There is a point at which a higher concentration of bleach adds NO additional ability to kill mold/bugs/whatever. That point comes at about a 5:1 solution of regular clorox. That is, 5 parts water to 1 part clorox. Mix it stronger than that and you are just wasting clorox.
RT Firefly
Enigma
Greetings,
Mr. d. 5:1-got it, thanks.
Mr. d. 5:1-got it, thanks.
Be careful if aluminum tanks - can cause aluminum hydroxide and aluminum chloride:
http://boards.straightdope.com/sdmb/showthread.php?t=410459
http://boards.straightdope.com/sdmb/showthread.php?t=410459
ulysses
Guru
To "shock treat" a new tank 50 parts of bleach to 1,000,000 parts of water. Then completely flush. For maintaining a Chlorine residual 2 parts bleach to 1,000,000 gals of water. Remember that what you think is a gallon of bleach is really only 5-7 % Hypo-chlorite solution. You can purchase a simple test kit from Hach that will allow you to maintain that 2ppm. That is lower than most swimming pool kits will go. Note, I am not associated with Hach but do use a lot of their test equipment in the water industry.
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"To "shock treat" a new tank 50 parts of bleach to 1,000,000 parts of water."
Did you mean 50 parts of chlorine to a 1,000,000 parts of water?
Fifty gallons of 7% Clorox in a million gallons of water really doesn't sound like much.
Puriclean is another option for cleaning tanks and it won't hurt aluminum tanks.
Link: http://www.cleantabs.co.uk/puriclean.htm
Puriclean
Cleans and purifies all stored water systems in Boats – Caravans – Motor Homes – Coaches
Puriclean is easy to use, it is simply added to the water system and left to soak for 1 to 12 hours then rinsed. Periodic use will ensure a clean healthy system for water storage
When filling the tank, treat the water with Aqua Clean Tabs or Aqua Mega Tabs
Sizes
Did you mean 50 parts of chlorine to a 1,000,000 parts of water?
Fifty gallons of 7% Clorox in a million gallons of water really doesn't sound like much.
Puriclean is another option for cleaning tanks and it won't hurt aluminum tanks.
Link: http://www.cleantabs.co.uk/puriclean.htm
Puriclean
Cleans and purifies all stored water systems in Boats – Caravans – Motor Homes – Coaches
- Unique dual purpose formula which both cleans and sterilises in one easy action
- Cleans the complete water system: tank, pipes, pumps, taps
- Eradicates bacteria, viruses, biofilm, algae and fungi
- For maximum results, simply soak and flush
- Powerful action without harming the components in the water system
- Proven in use world-wide for 3 decades
When filling the tank, treat the water with Aqua Clean Tabs or Aqua Mega Tabs
Sizes
- 100g Cleans tanks up to 90 litres
- 400g Cleans tanks up to 270 litres
- 4 kg Cleans tanks up to 2500 litres
ulysses
Guru
No, what was stated was 50 parts of chlorine to one million parts of water. Not 50 parts of Clorox. Clorox's active ingredient is sodium hypochlorite usually between 5-8% . In other words what we call bleach is not entirely chlorine. Chlorine is a fairly dangerous substance therefore you will not find it in a liquid state in any solution over 12% in the U.S. and that is an industrial strength commercial N.S.F. approved grade bleach. Most large water systems inject a chlorine gas into the drinking water with the very deadly gas located in a side building away from the plant operations and with alarms and remote shut downs associated within the chlorine building. Even then they will place a open bottle of ammonia near the door. As those substance come in contact a white cloud of smoke will provide a visible indicator of a leaking chlorine cylinder.
So, doing the math to get one gallon of active chlorine out of what is marketed as clorox it will take about 14 gallons at 7% solution. So if you had a million gallon water tank it would take 14 X 50 = 700 gallons to make a 50ppm chlorine / water treatment.
Both the 50 ppm shock type treatment and the 2 ppm maintenance are provided in the Rules for Safe Drinking Water.
As with most things in life there are good and bad aspects of anything we do. I would not suggest the shock type treatment very often, it is usually not necessary except with a new tank. Chlorine is corrosive and may lead to an increase in lead or copper in the drinking water especially if you have an older boat that may have bronze, brass, or lead in the fixtures or plumbing.
Given a 3 hour contact time between the small amount of chlorine added to a tank for maintenance and the water coming out if there is a residual (after contact) chlorine present even just a trace amount then there are no bad bacteria in the water.
I will research the "Puriclean" product. I have not heard of it used in commercial water treatment facilities.
So, doing the math to get one gallon of active chlorine out of what is marketed as clorox it will take about 14 gallons at 7% solution. So if you had a million gallon water tank it would take 14 X 50 = 700 gallons to make a 50ppm chlorine / water treatment.
Both the 50 ppm shock type treatment and the 2 ppm maintenance are provided in the Rules for Safe Drinking Water.
As with most things in life there are good and bad aspects of anything we do. I would not suggest the shock type treatment very often, it is usually not necessary except with a new tank. Chlorine is corrosive and may lead to an increase in lead or copper in the drinking water especially if you have an older boat that may have bronze, brass, or lead in the fixtures or plumbing.
Given a 3 hour contact time between the small amount of chlorine added to a tank for maintenance and the water coming out if there is a residual (after contact) chlorine present even just a trace amount then there are no bad bacteria in the water.
I will research the "Puriclean" product. I have not heard of it used in commercial water treatment facilities.
