Gallionella ferruginea - A genus of stalked, ribbon-like bacteria which utilize iron in their metabolism, and cause staining, plugging and odor problems in water systems. (See iron bacteria.)
gallon - A unit of liquid volume; the U.S. gallon has a volume of 231 cubic inches or 3.78533 liters; the British (Imperial) gallon has a volume of 277.418 cubic inches or 4.54596 liters.
gate valve - A valve with the closing element that
is a disc which is moved across the stream, often in a groove or slot, for
support against pressure.
gel zeolite - A synthetic sodium aluminoscilicate
ion exchanger.
Giardia Lamblia - An intestinal parasite commonly found in water supplies originating in mountainous or wooded watersheds. It exists as a
free-swimming protozoan-like organism in warm-blooded animals' intestines,
causing chronic diarrhea, cramps, bloating and weight loss. Outside of the
intestines, it forms a tough cyst that protects it until it finds a new host.
Resistant to chlorine and most oxidizing agents, Giardia can be removed
effectively through filtration below 1 micrometer.
globe valve - A valve in which the closing element
is a sphere, or a flat or rounded gasket, which is moved into or onto a round
port.
gpg - Abbreviation for "grain(s) per gallon".
grain(gr.) - A unit of weight equal to 1/7000th of a pound, or 0.0648 gram.
grain(s) per gallon (gpg) - A common basis for reporting water analyses in the United States and Canada; one grain per U.S. gallon equals 17.12 milligrams per liter (mg/l) or parts per million (ppm). One grain per British (Imperial) gallon equals 14.3 milligrams per liter or parts per million.
gram (g) - The basic unit of weight (mass) of the metric system, originally intended to be the weight of 1 cubic centimeter of water at 4oC. (One pound is 454 grams.)
greensand - A natural mineral, primarily composed of complex silicates, which possess ion exchange properties. (See manganese greensand,
zeolite.)
