[D31] Fresh water tank maintenance

[D C (Mac) Macdonald]

There has been considerable discussion on the "Great Loop"
list recently regarding fresh water supply and how to keep
it "sweet and clean."  The following message contains some
REALLY good info that I believe is applicable to all.

I have already posted it on the PSML mail list.

* D C "Mac" Macdonald, AP *
*  m/v Another Adventure  *
* Grand Lake (OK) S & P S *
*  Oklahoma City S & P S  *
*    USCGAux and AGLCA    *


----Original Message Follows----

To: "T&T Great Loop List" <great-loop@lists.samurai.com>
Subject: GL: Fresh water tank maintenance
Date: Wed, 27 Jul 2005 19:52:10 -0500

OK, here are some links to start with:
http://www.collierem.org/h2o_pure.htm
http://home.earthlink.net/~alanwdove/Water.html
(A LONG and exhaustive research paper on water
and it's purification)

______________

Here's Peggie Hall's description of how to sanitize and maintain
tanks:

Fresh Water System Problems [Fresh water system problems--foul
odor or taste--are typically caused by allowing water to stagnate
in the tank and especially the lines, creating the ideal
environment for molds, fungi and bacteria that thrive in damp
dark places. Here's the recommended method for re-commissioning
fresh water systems; this should be done at least annually:

Fill the water tank with a solution of 1-cup (8 oz) of household
bleach per 10 gallon tank capacity.  Turn on every faucet on the
boat (including a deck wash if you have one), and allow the water
to run until what's coming out smells strongly of bleach.  Turn
off the faucets, but leave the system pressurized so the solution
remains in the lines.

Let stand overnight-- at least 8 hours--but NO LONGER THAN 24
hours.  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, 'cuz 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, repeating till the
water runs clean and smells and tastes clean.

Cleaning out the tank addresses only the least of the problem...
most of the problem occurs in the lines, so it's very important
to leave the system pressurized while the bleach solution is in
the tank to keep the solution in the lines too.

People have expressed concern about using this method to re-
commission aluminum tanks.  While bleach (chlorine) IS corrosive,
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.

To keep the water system cleaner longer, use your fresh water...
keep water flowing through system.  The molds, fungi, and
bacteria only start to grow in hoses that aren't being used.
Before filling the tank each time, always let the dock water run
for at least 15 minutes first...the same critters that like the
lines on your boat LOVE the dock supply line and your hose that
sit in the warm sun, and you don't want to transfer water that's
been sitting in the dock supply line to your boat's system.  So
let the water run long enough to flush out all the water that's
been standing in them so that what goes into your boat is coming
straight from the water main.

Finally, while the molds, fungi and bacteria in onboard water
systems here in the US may not be pleasant, we're dealing only
with aesthetics...water purity isn't an issue here--or in most
developed nations...the water supply has already been purified
(unless you're using well-water).  However, when cruising out of
the country, it's a good idea to know what you're putting in your
tanks...and if you're in any doubt, boil all water that's to be
drunk or used to wash dishes, and/or treat each tankfull to
purify.  It's even more important in these areas to let the water
run before putting it in the tank--wash the boat, whatever it
takes...'cuz any harmful bacteria will  REALLY  proliferate in
water hoses left sitting on the dock.

_____________________________________


Personally, I don't think it's useful to use a charcoal filter on
the water going INTO your tank, because it'll remove beneficial
things like chlorine/bromine, etc. that will help keep your water
good.  A sediment filter is a whole other story.  I think you can
skip the entire battery of laboratory tests... if your water
stinks you already know you have a problem!  Pump it all out,
open up the tank and scrub it if you can, then sanitize it per
Peggy's instructions and be careful what you fill it with.

Use it up often; don't just let it sit in there.  I stay on shore
water most of the month, but on the first I switch to tank water
and use it all up, refill with fresh, then back to shore water
(I like the pressure).

Somebody wrote: "If you get a sulfur smell from your hot water
only... this could be the zinc rod in your hot water tank.
Remove the plug and rod, ususally on top of your tank.  Cut the
rod off and only reinstall the plug back in."  That is  REALLY
bad advice!  The whole reason that "zinc" (which is actually
magnesium in fresh water) is there is to keep your hot water
tank from corroding; it's a sacrificial anode.  Sulfur smell
from the water heater means that you have internal tank
corrosion already, and the magnesium anode is either gone or
ineffective.  A lot of folks don't even know they have an anode
in their water heater.  Check it.  If you're already getting that
sulfur smell from the hot water heater only, it's probably time
to replace it anyway.

For anyone concerned about using chlorine bleach, you can also
use iodine.  Household iodine from the medicine chest of first
aid kit will purify water.  The iodine should be 2% United States
Pharmacopoeia (U.S.P.) strength.  Add 20 drops per gallon of
clear water.  Seal the container and let stand for 30 minutes.
The water supply will be safe for an indefinite period.

Now, how many drops to add to 160 gallons of FW? It appears that
20 drops = 1 cc.  So you need 1 cc/gallon, or about 0.68 cups.
Conversion is 1 cup = 237 cc.  

If you're paranoid about healthy water, just take bottled water
along!  There are some expensive filtration/sterilization units
available if you're cruising to countries with suspect water
supplies, but they're probably overkill for US water supplies.
I have a little PUR filter on my galley sink tap, and it works
great to "final filter" any water I drink or make coffee/food
with.

...and that's all I have to say about that.

Keith
__
He who laughs last, thinks slowest.
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