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[compost_tea] Re: Effects of chlorinated water



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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