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22 responses total.

We were buying jugs of spring water but six months ago switched
to using a PUR/Brita pitcher system.  Works great in terms of
eliminating the dry, chlorine taste, yet it spares the flouride.

Bear in mind that Ann Arbor has much cleaner, better tasting water than a sot
of cities, so your perception of "needing a filter" may be a bit off.  I've
been in small towns where the tap water tasted like swimming pool water!

Yeah, our water is pretty good, but nonetheless, cleaner 8is* better, to quote
an ad for Pur.  ;)

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CU rated them a few months ago (the issue's around here somewhere).  They
found a pretty wide range of talent in the filtering abilities.  There are
some basic measures you can take if you're worried about lead pipes (or
lead solder) - never drink or cook with (tap) hot water, run the water a
bit before using to discard what's been sitting in your pipes, etc.

Perhas one should run the water long enough to be sure that you arn't getting
the stuff that has been sitting in the city mains either ;-)  I wonder if
any of the mains are made of lead?  I wouldn't be surprised if some of those
pipes down there are close to 100 years old.  I wonder how many of the iron
pipes are packed with lead?  I also suspect that most of the old ones are
coated with a nice, protective, coating of calcium, lime, etc. like our hot
water heaters.

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We have friends who had a water filter.  After a while (~1 year?) she
developed a rash around her mouth at about the same time that their
filter started giving off "musty tasting water".  After trying to treat
the rash with the usual battery of cures, she stopped drinking the filtered
water.  The rash went away and the filter became fill for some land fill.

Valerie doesn't say what she wants to "filter" from her water. Filters,
technically, just remove particulate matter, which can also include
bacteria. Removal or hardness or other chemicals requires absorption
and/or ion-exchange. CU uses the term "filter" for these treatments too.
The better overall term is "water purification systems". 

Most "taste" improving filters use activated charcoal. This also removes
some chlorine and lead, but does nothing for hardness or bacteria. Ion
exchange resins remove hardness and heavy metals (lead, copper). Some
filter cartridges have both charcoal and ion-exchange resins. Finally, to
remove pathogens, requires extremely (sub-micron) filters. Pathogen filters
are not needed in public water supplies that are chlorinated (or ozonated),
but are now necessary when camping and drinking from rivers and lakes
(thanks to human habits, which have introduced giardia and other noxious
stuff into wilderness water).

CU (7/97) has it right - determine first what you want to remove from
your water supply.

Incidentally, that case of a filter eventually producing "musty" water -
bacteria and molds will grow in filters, especially if the water is not
adequately chlorinated, or if chlorinated water is not flushed through
regularly. Having such filters sitting around with little use is asking
for molds to grow. Even laboratory installations have problems with this,
and are back-washed and treated with Chlorox (!) regularly. 

That would explain it.  These friends were on a well.

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We filter mainly to remove the chlorine and ammonia, which combine to form
a stinky compound that I can smell in my hair.  THe ammonia is put in to keep
the chlorine from evaporating - they combine to form chloramines.  Otherwise
city water is pretty clean, having already been filtered through sand and
charcoal.  They add chlorine just for insurance, in case something leaks in.
There are two kinds of carbon filter - granulated and carbon block, which
remove respectively 97 and 99% of the chlorine, when new.  After they get
filled up with chlorine they absorb less.  When you can smell or taste the
water coming through they should be changed!!!  Sears used to sell block
filters for $20.  We bought a case of them for $7 each, and can sell them to
someone for $10 (to account for inflation) or let you know the place to buy
a case of 20.  Old filters look brown, having accumulated enough particulate
matter in them that bacteria can grow in the filter, but supposedly they do
not get through the carbon block because the pores are too small.  But their
waste products get through and taste and smell bad.  You can buy a chlorine
test kit from a swimming pool place for about $8.  The water turns yellow when
you add a reagent if there is chlorine getting through, and then you can
change it before the pointt where it smells.  Or you can change it every year
just to be sure, if you don't want to test the water.  (Keep the test kit in
the fridge and it is good for many years).  We have put in a larger filter
(20" long, in a 'big blue' housing) to filter all the water in the house. 
These run about $35, I think, and one has lasted us several years, but for
typical usage you would change them at least once a year.  I can smell the
chlorine when I do laundry - like a swimming pool.  Our drinking water has
3 ppm (parts per million) chlorine in it, and home swimming pools only have
1 (municipal onnes have 3).  Chlorine forms carcinogenic compounds with
organic molecules, and destroys vitamins when you cook in chlorinated water.
And it tastes bad.  Write in for addresses for filters and test kits, I can
hunt for them.  You can also buy a bacterial filter, but ours has not
collected any bacteria for over two years.  City water is already pretty
clean, except for the chlorine and ammonia.

Sand and charcoal do not remove bacteria and viruses. The chlorine is
added solely to disinfect the water. Otherwise not only harmful organisms
could get through, but all sorts of molds and common bacteria would
grow in the mains, adding (dis)taste to the water. The addition of ammonia
also makes the chlorine less active so that it forms fewer harmful
chlorinated compounds (like chloroform, etc). I think Ann Arbor now ozonates
its water, doesn't it?

 
Yes it does.  We went on their annual tour this last spring and the
building where they ozonate the water is quite impressive with all
its stainless plumbing and ozone generators.  Since ozone is very
unstable, it can not keep the mains clean, as Rane said.  Amonia is
no longer added, from what I understood.  When I tested for it, over
a year ago, I found none.  (Water test kit for tropical fish.)

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I don't know about the tours, but a few years ago I called up the water
plant and asked for their most recent test results.  They were happy to
send me the summary and a lot of details.  It made for interesting
reading.  Others concerned about the city water supply might want to
do the same, in addition to the testing they do at home.

On the tour, they said they ozonate, and then add both chlorine and ammonia,
in the form of chloramine, I think (the combination).

They use to use chloramine but built the ozone facility to meet new
water quality requirements.  Now they just add a little chlorine to
keep the water disinfected while it travels around in the water mains.
Ozone is very unstable and can't do that job.

I went after they started ozonating, and I think they said they still add
chloramine, because chlorine comes out of the water too easily.  One of us
should call and check on it.  Chloramine is much harder to filter out, we had
to put in a large whole-house filter.

The ammonia reacts with the chlorine to form the rather unstable compound
chloramine. In effect, this reduces the immediate concentration of 
chlorine, thereby reducing the tendency to chlorinate other substances to
from things like chloroform, while providing a reservoir of chlorine 
that lasts longer in the water mains. This also reduces the amount of
chlorine that has to be added to ensure that a suitable level gets to
the far reaches of the system.

But are they still adding chloramine, or just chlorine?

They add chlorine *and* ammonia. Chloramine itself is a highly explosive
liquid. The chloramine is formed in solution (no, its not explosive in
solution).

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