Well, it's *not* "color developer starter"; I always get it mixed up
and then remind myself that that's the _wrong_ product.  I will browse
a bit and see if I can find the right one on Kodak's web site.

It's basically just a plastic envelope full of highly soluble mineral
salts that give you the exact water Kodak formulated their photographic
chemicals for, when added to distalled water.  It's cheap, too.

I haven't used it myself in years, because I no longer live somewhere
where well water (and well water with too much dissolved iron and
sulfur to be good for photo processing, at that) is the norm.  But if
you want to be able to follow Kodak's recommendations for touchy
processes like, say, E-6, with confidence, and you're using distilled
water to mix the stock solutions, it's a really good idea (and it won't
hurt to use it for black and white processing, either).

 I have also heard this but never seen any substantiation.
Kodak _does_ make its products with the idea that less than
ideal tap water is going to be used to mix them but the
difference is in the use of buffering agents to compensate
for water pH and the addition of sequestering agents to keep
calcium and magnesium carbonates in the water from
precipitating on the emulsion. Bottled drinking water has
minerals in it for flavor. Really pure water tasts very flat
as does completely de-aereated water.
  Water can be improved for photographic purposes by
boiling it. Boil the water for about five minutes and allow
it to sit and cool. Then syphon off the clear water. Boiling
serves three purposes: it drives off dissolved gasses (like
air and chlorine); it reduces temporary hardness by
converting some of the dissolved carbonates into insoluble
form. They then are deposited on the walls of the vessel or
are precipitated and fall to the bottom of the vessel. It
coagulates any organic matter which also is precipitated
during cooling. The last is probably of no significance in
city water systems but may be important for well water.
  Since Aluminum and copper can cause fogging its best to
use a container of some other material for boiling. Boiling
will NOT remove chloramines, currently used in many city
water supplies in place of chlorine. This can be removed by
the use of an activated charcoal filter like a Brita filter.
Neither chlorine or chloramines appear to have any effect on
photographic chemistry. Chlorine is destroyed by hypo.
  Dirty water is probably a worse problem in most places
than the purity. A good water filter is helpful but even a
coffee filter will help a lot. The use of a rinse of clean
water after washing will remove dirt from dirty wash water.
I suggest a rinse as follows:

Water to 1 liter
Isopropyl alcohol, 99%  25 ml
Kodak Photo Flo         2.5 ml (half strength)

70% Isopropyl rubbing alcohol can be used, the amount is
then 35ml. Just make sure its just alcohol and water, not
the kind with Oil of Wintergreen or other flavorings in it.

Soak the film in this for about two minutes and hang up to
dry without sqeegeeing.
Prints can be rinsed in plain clean water and squeegeed off
with a soft sponge before drying.

According to Kodak, at least, chlorine and chloramine in tap water (at
least at levels permitted for drinking) don't have any effect on
developers or development.