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The treatment process consists of a series of steps. First, raw
water is drawn from the Allegheny River where potassium permanganate
is immediately added to help remove iron and manganese. Then it
is pumped to a rapid mixing tank where powdered carbon, polyaluminumchloride
and soda ash are added. The addition of these chemicals cause small
particles to adhere to one another (called "floc"), making
them heavy enough to settle into a basin from which sediment is
removed by mechanical scrapers. After the rapid mix, the water flows
to the slow mixing chamber. Fluoride is added to prevent tooth decay
and chlorine for disinfection. After the slow mix the water travels
to the sedimentation basin and the heavier particles settle out.
The water travels to the top of the filters where it passes through
layers of fine coal, silicate sand and gravel. As the smaller, suspended
particles are removed, clear water flows into underground storage
chambers. Chlorine is added again for disinfection along with phosphate
for corrosion control. Sodium Hydroxide is added to raise the PH
to the desired level. Before water leaves the treatment plant, ultraviolet
disinfection is used to destroy microbiological contaminants, such
as cryptosporidium parvum. 
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