Water is pumped into the treatment plant from the reservoir or
stream through  rotating screens .
Alum is added to cause flocculation .
After rapid mixing (20-40 minutes), the water remains in  the settling basin
while sedimentation of floc occurs (2-4 hours). The sediment (sludge) is pumped
from the bottom of the pools and stored in holding lagoons to dry.
The softening process  involves the addition of sodium carbonate and hydrated
lime to remove calcium and magnesium ions that are responsible for water
hardness. This process takes an additional 2-4 hours. For each pound of chemical
used in the treatment process, two pounds are removed.
After an additional sedimentation process , carbon dioxide is added to lower
the pH level to approximately 7.5. Water is held in a  stabilizing basin for
another 2-4 hours.
Water then flows through large dual media rapid sand filters made up of layers
of gravel, sand, and anthracite coal .
Addition  of chlorine to disinfect the water, fluoride to protect teeth and a
corrosion inhibitor take place at the end of the process before water enters
 large underground clearwells to be held until needed by the community .
Please note: when ground water is used, neither screening nor initial
sedimentation is needed.
In 1903, $46,000 was provided for an initial testing facility to analyze the drinking water and wastewater. These
experiments resulted in the construction of the Scioto Water Purification Plant
and Pumping Station on Dublin Road which was completed in 1908. This major
project became known internationally as "The Columbus Experiment" and was the
first water plant to combine filtration and water softening. This plant replaced
the first water supply system placed in operation May 1, 1871 which consisted of
a well and the Westside Pumping Station built at the confluence of the Scioto
and Olentangy Rivers.
Two brothers, Clarence Hoover, chief chemist and bacteriologist of sewage
treatment, and Charles Hoover, chemist in charge of the water plant, were
instrumental in inventing methods of water and wastewater treatment that are
still used today. They helped to shape water treatment and were committed to
continuously improving treatment methods. Charles Hoover is credited with the
co-discovery of a water softening process using lime and soda ash. Their efforts
reduced the number of deaths resulting from typhoid in the early 20th century.
In the 1940s, along with plans to construct a reservoir on Big Walnut Creek,
came the design for a new water treatment plant. This plant would produce almost
double the amount of water being supplied by the Scioto River Plant and the
recently added Nelson Road Water Plant.
In June of 1956, the Big Walnut Water Treatment Plant located on Morse Road was
completed with a capacity to treat 50 million gallons of water daily. The
population of metropolitan Columbus at the time was approximately 620,000. In
1969, expansion increased the Morse Road plant's treatment capacity to 130
million gallons a day as Columbus grew to a population of almost 900,000.
Shortly thereafter, construction began on additional treatment facilities. In
1975, a new water plant was completed on the original grounds of the Scioto
Water Purification Plant and Pumping Station. This plant is known as the Dublin
Road Water Plant. In 1979 in southern Franklin County, results of geological and
hydrological testing led to the development of the wellfield and the
construction of the Parsons Avenue Water Plant.
In 1996, the Division of Water provided an average of 134 million gallons of
drinking water daily to the more than one million residents, businesses, and
industries that make up the Greater Columbus Area. The Morse Road Water Plant
(renamed the Hap Cremean Water Plant in 1988) provided an average of 67 million
gallons daily; the Dublin Road water plant provided 47 million; and the Parsons
Avenue Water Plant provided 20 million.
These water plants are constantly upgraded to meet the demands of this growing
community and new regulations.
A new automated system for process control and additional underground clearwells
were installed at the Hap Cremean Water Plant. The clearwell expansion increased
the plant's storage capacity by 50 million gallons. At the Parsons Avenue Water
Plant, additional wells will soon be added to increase the supply source.
These three plants are the strength that supplies quality water to the Greater
Columbus Area. Water drawn from the reservoirs and wells must undergo a complex
treatment process and meet stringent Federal and State EPA standards before it
can be distributed to the public.