HomeRoast Digest


Topic: Reverse Osmosis Systems (43 lines)
1) From: Jim Whitesell
I have 15 years of experience with these as a multiple homeowner. I  
like Watts and they have great customer support:http://www.wattspremier.com/Costco and Sams often carry these at or below $200, which is a good  
price given what you are getting. If you put a unit in the kitchen,  
get an ice maker kit from Watts directly (nothing more than a T and  
some polyethylene line and fittings, but the latter are plastic) as  
the purified ice will make nice looking ice cubes (not as clear as  
dedicated ice makers make, your RO ice cubes will have bubbles of  
trapped oxygen/nitrogen which become progressively more soluble as the  
temperature decreases until the water starts to freeze. And a  
chemistry lesson---gases are less soluble in hot water than cold, so  
as you bring water to a boil, they will escape. As you near the  
boiling point, all those bubbles are from escaping gases, not water  
vapor so that is why you need a rolling boil to really have 212 degree  
water).
Now there are two things (related) about RO water that you should  
know, both hinge on the fact that essentially ALL minerals are removed  
by the unit.
The water is extremely corrosive as essentially pure water has a great  
power to leach metals into it. Sort of counter intuitive. So all  
installations that are done right will use plastic rather than copper  
or brass fittings. Have no idea what the long term issues are with a  
boiler, but I would not want to use RO water with anything other than  
stainless. Just a very little bit of simple salt would solve this  
problem.
Minerals add taste to water so coffee made with RO water versus say  
bottled spring water will probably differ----only the taster can say  
which they prefer. Either would be better than most city tap water.
Jim Whitesell (Chemist, UCSD)


HomeRoast Digest