[compost_tea] Re: Effects of chlorinated water

From: compostanne <Anne.C.Donahue_at_ci.eugene.or.us>
Date: Thu, 24 Jul 2003 18:10:57 -0000

Incredibly wonderful ICTC conference this month. Thank you everyone
for a wonderful time.

It seems to me we could pay for a couple SFI tests, one that showed
microbe counts in the tea, and the other showing microbe counts in
tea pulled through a hose bib via a Siphonject which will dilute the
tea with 16 parts water. Drawing the diluted tea for testing from
the end of the drip tubing will tell how the organisms have changed
through their brief encounter with chlorinated water.

We are fortunate in Eugene Oregon to have incredibly clean water from
the McKenzie River as our source, which needs only minimal treatment
with chlorine gas.

A similar test with chloramine treated water will provide essential
information to those who have chloramine in their water.

I questioned the supervisor of our local water treatment facility
regarding the use of chlorine in our water and the effect of that
chlorine on compost tea. We posted this information for our local
Master Gardeners. It may be helpful to this discussion.

It's long, so pull up a chair and a cup of tea....
And remember this is for a water source treated with chlorine gas,
not chloramine...


 The following is a series of questions asked by Anne Donahue,
Compost
 Specialist for the City of Eugene to Doug Wise, Supervisor of Water
 Treatment and Filtration for the Eugene Water and Electric Board in
 Eugene, Oregon.

 Anne:
 Not many Master Gardeners realize what a hidden jewel of expertise
we
 have in our midst. Can you share with us what you do for EWEB and
how
 you have come to be our local "water expert"?

 Doug:
 I did my apprenticeship in a filter plant going to college, studied
 and assisted the microbiologist in Denver, worked as a treatment
plant
 operator in Aurora, Colorado after teaching high school and then
moved
 to Eugene where I've been an operator, water quality lead and Water
 Supply and Treatment Supervisor for EWEB for the last 23 years.
Also,
 I've passed five four-hour examinations and attended different water
 treatment conferences and classes over the years. I have a Masters
 Degree in Public Policy, Planning and Management from the University
 of Oregon.

                * * * * *
 Anne:
 Can you tell us where our water comes from, and in general, how it
 makes it way to our tap? How does the water source/system of Eugene
 differ from Springfield?

 Doug:
 The McKenzie River is one of the clearest and cleanest sources of
 surface water imaginable. There is very little commerce or industry
 upstream from our community and it is one of three rivers in Oregon
 which will not have any future discharge permits (sewerage outfalls)
 issued by the DEQ, so it will stay clean. We take the water and
 disinfect it with chlorine and then add aluminum sulfate (high
quality
 pickling alum) which "catches" the negatively charged dirt particles
 with the positively charged aluminum ions. We settle out the floc
that
 is formed from this reaction before we filter out any remaining
 particles. Our water is very soft and we add lime (just over half a
 dry ounce of calcium oxide per thousand gallons) to raise the pH to
 7.7 so the water won't corrode plumbing fixtures, reducing the risk
of
 lead or copper leaching. We also take some chlorine OUT leaving
only
 one-half part per million as it leaves the plant. The average
 chlorine in the distribution system (customer taps) is 0.32 mg/l
 (parts per million). Most people's noses can detect chlorine in the
 water at about 0.4 mg/l...just above our delivered dosage.

           * * * * *
 Anne:
 Why is chlorine added to the water? How much chlorine is added to
the
 water? What is the difference between chlorine and chloramine, and
 why do we use chlorine and not chloramine as Portland does.

 Doug:
 This is an easy one. Few people in this country have feared
 typhoid,cholera, amoebic dysentary, bacilliary dysentary or other
 water borne illness since the advent of chlorine disinfection. It
is
 even effective (eventually) against Giardiasis (beaver fever).

 To assure disinfection, we average about 1.6 mg/l of chlorine added
to
 the raw water, or about a third of what you might expect in a
swimming
 pool. After the demand is met (killing bacteria and oxidizing
organic
 carbon) and the treatment process is complete, we still have between
 0.8 and 1.0 mg/l of chlorine in the water. We reduce this to 0.5-
0.1
 leaving the plant.

 Free chlorine -- the kind EWEB uses -- is a dissolved gas, just like
 the carbon dioxide in soda pop. Soda usually has a pressure of 14
 psi. The water is under 80 psi on average so the chlorine will
 "escape" the solution as quickly as it can when the pressure is
 relieved. This happens when customers open their tap.

 Interestingly, the effect of chlorine leaving solution causes two
 types of common complaints. The first is that "my water smells like
 chlorine, especially in the morning." The gas leaves the solution
 during the night in the warm house and the first spurt of water
pushes
 the gas out, often with a noticeable odor in the shower or the
sink.
 The second common complaint is that "when I leave my water on the
 nightstand, it tastes different." This too is because the water
can't
 hold the naturally dissolved oxygen, carbon dioxide and chlorine.
When
 these products off-gas, the water tastes different.

 Chloramines are used when a water system is too large or lacking
 steady pressure to keep a free chlorine residual and, therefore, may
 be at risk of bacteria and other pathogens. The upside of
chloramines
 is that they hang around a LOOONG time. The problem is that they
are
 much less effective as a disinfectant, by the order of ten times or
 even 100 times depending on the source water. Chloramines are also
 hard to get rid of in water. Pet stores sell de-chlor which is
NEEDED
 in chloraminated water. Free chlorine can be removed simply by
letting
 the water set in an open container for "a half hour" or so.

           * * * * *
 Anne:
 Does the chlorine dissipate by the very act of overhead watering?

 Doug:
 Most of it will. This is a good way to reduce chlorine, but without
 measuring the collected water, the exact amount of chlorine
remaining
 might vary.

           * * * * *
 Anne:
 Will the chlorine damage the beneficial organisms on leaf surfaces
if
 I overhead water?

 Doug:
 This is a tough one. Define and quantify "beneficial organisms" and
 describe the chlorine dose. Soaking a leaf in Chlorox (50,000 parts
 per
 million) will clean most anything in a half hour. Last week each
drop of
 McKenzie river water contained about 1,200 total (aerobic) bacteria.
 Contact with 1.6 mg/l of chlorine for four or five hours reduced that
 number to the 2 - 3 range (without filtration). So yes, high
 concentration for a lengthy time might diminish advantageous
populations.
 It would also impact plant pathogens.

           * * * * *
 Anne:
 Will it damage beneficial organisms in my soil if I water my garden
 through drip irrigation?
 Doug:
 Almost assuredly not. There are LOTS of soil bacteria, many of
which
 are used as indicators of soil health, but some of which are also
 indicators of contaminated water. Citrobacter, Klebsiella and
several
 aeromonas species as well as E.coli bacteria are common in soils and
 may be opportunistic pathogens. The chlorine concentration in the
 water is used up VERY quickly by "dirt". We call this chlorine
 demand. My guess is that too much water would do more damage from
 limiting oxygen uptake than by the chlorine in the water. Dumping a
 swimming pool or hot tub might be an exception since these commonly
 have buffers to keep the disinfectant "active".

           * * * * *
 Anne:
 If I use a hose end sprayer to spray compost tea, will I lose
 organisms in the tea as I spray?

 Doug:
 Relative to billions, yes, relative to safe drinking water, no.

           * * * * *
 Anne:
 If I dilute compost tea with city water will I kill the beneficial
 organisms in the tea?

 Doug:
 Not if it's disinfected with reasonable amounts of "free chlorine".

           * * * * *
 Anne:
 If I wanted to remove the chlorine altogether, how would I do that?

 Doug:
 There are several common commercial products out. Sodium bisulfite
 used for wine-making works. Sodium thiosulfate, the active
ingredient
 in most aquarium dechlorination products works. My common joke is
 that a spoonful of dirt will create enough chlorine demand to kill
any
 residual. Or a finger stuck into a glass of water. Another product
 that works well is vitamin C or ascorbic acid, though it lowers the
pH
 and may corrode metal products over time.

           * * * * *
 Anne:
 How long will water have to sit in a bucket for the chlorine to
 dissipate? How does that time change if I have an air stone bubbling
 in the bucket?

 Doug:
 My rule of thumb for customers who are really concerned about
chlorine
 in the water is to let a container set in a refrigerator
 overnight...or keep "standing" water replenished since "old water"
 will have enough demand to use up the chlorine.

 Any aeration or agitation will speed the loss of chlorine gas from
 solution. Probably, the airstone from an aquarium or tea-bucket will
 have enough chlorine demand to do the trick all by itself.

           * * * * *

 Anne:
 What if I add vitamin C? How much per gallon of water, or five
gallon
 bucket?

 Doug:
 Dust on a finger will handle a gallon or more. Two pounds of
ascorbic
 acid will handle 120,000 gallons of water with a chlorine residual
of
 1.0 mg/l.

 Anne:
 What if I toss in a tablespoon of soil or compost, will the chlorine
 bind to that soil/compost? (And why/how does it bind to the soil? Is
 it binding to the organic material, or the soil components: sand,
 silt, and clay? i.e., does the percent of organic matter in the soil
 determine how chlorine is bound in the soil? Once bound, what
happens
 to it?)



 Doug:
 Chlorine (and bromine and iodine and fluorine) all act to oxidize
 natural organic matter (NOM) by forming complexes with them.
Chlorine
 vigorously attacks many chemical bonds and replaces a variety of
atoms
 or molecules making new compounds. In bacteria, it may attack the
 cell wall or membrane, preventing nutrition and reproduction even
when
 it doesn't kill the organism. Sunlight typically breaks these new
 bonds when it gets a chance. Or any reducing (anaerobic) environment
 will work on chlorinated compounds pretty aggressively.

           * * * * *
 Anne:
 In essence, if using city water, are you "sacrificing" the organisms
 in say, a teaspoon of tea, for every gallon of tea you use? (I'm
just
 trying to get an idea of the amount of damage that is done by the
 chlorine in the
 water)

 Doug:
 Maybe the organisms in a small drop of tea.

           * * * * *
 Anne:
 Do you have any further thoughts to share about the quality of our
 local water?

 Doug:
 Eugene uses a multiple barrier approach to improve an outstanding
 water source. We have detected no organic pesticides in the river
 water over the last 95 years and we now screen for more than
 five-dozen different organic chemicals regularly. That doesn't mean
 there is "zero". It just means that we can't find any looking in
the
 range of 50 - 500 parts per trillion. At these levels, if there was
a
 chemical detected, I'd have to drink eight glasses of water a day
for
 720 years to be sure of drinking a single drop of the chemical.

 We have remarkable few minerals or other inorganic chemicals. The
 treatment process reduces all metals by 30 - 70 percent and we are
 mostly ND (not detected at measured levels) for heavy metals.

 In short, we know what is in the water, and more importantly, what
 isn't. And we're able to share this information with the confidence
of
 decades of consistent test results.

 Thanks for the questions. The answers are a little general, but may
 be useful for gardeners with concerns.



 Anne Donahue
 Compost Specialist
 City of Eugene Planning and Development Department
 99 West 10th Ave
 Eugene, Oregon 97401
 Phone: (541) 682-5542
 Fax: (541) 682-6806





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Received on Thu Jul 24 2003 - 23:41:15 EDT

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