Civil Engineering Reference
In-Depth Information
patent in 1791 when he described a water filter using carefully placed graded layers
of sand and gravel. Baker reports that the first town to have filtered water was Paisley,
Scotland, in 1804—although the filtered water was transported to individual houses
by carts. Three years later in Glasgow, filtered water was being piped to customers.
By the early 1800s, centralized water treatment using sand filtration had been adopted
by towns across Europe.
In 1799, Philadelphia, Pennsylvania, was the first U.S. city to build a public water
system that distributed water through a system of pipes. Richmond, Virginia, on the
James River, was the first town in the United States to build a centralized water
treatment facility using sand and gravel filters in 1832, but it would take until the late
1800s for sand filtration to be widely adopted.
Filtration and Waterborne Disease
As advancements were being made in water filtration to improve primarily the aes-
thetics of drinking water, scientists were also beginning to understand the health sig-
nificance of water. Dr. John Snow's landmark epidemiological studies linked, for the
first time, contaminated water supplies as the causal agent in cholera outbreaks in
London. In 1854, he concluded that a leaking sewer pipe had contaminated the water
well located at No. 40 Broad Street, and when he removed the pump handle from the
well, the outbreak subsided.
Dr. Snow also conducted detailed epidemiological studies on the water supplied by
the Southwark and Vauxhall Company and the Lambeth Company. The former com-
pany obtained water from the Thames River in the middle of London, in an area
polluted with sewage, whereas the latter obtained Thames River water upstream of
London. Studies in an area served by both companies showed that the people receiving
water from the Lambeth Company had a low incidence of cholera, whereas those
served by the Southwark and Vauxhall Company had a high incidence. Because all
other environmental factors were the same for both groups, Snow concluded that chol-
era was being spread by the water supply.
In the United States, typhoid was the disease of greatest public health concern. By
the 1850s, typhoid outbreaks were common, causing thousands of deaths per year (see
Fig. 1-1
3
). Although known to be highly contagious, the routes of exposure and in-
fection were largely unknown. It wasn't until the late 1880s, when Louis Pasteur
proposed his ''germ theory'' of disease, that scientists began to understand how mi-
croscopic organisms were responsible for sickness and disease.
Dr. Robert Koch provided the correlation between water filtration and protection
against disease when, following an outbreak in 1892, he examined the incidence of
cholera cases in the two German towns of Hamburg and Altona. Both of the contiguous
cities drew water from the Elbe River. However, Altona filtered its water, since the
water they withdrew was downstream of Hamburg and heavily contaminated. The
results of Koch's study were conclusive. Despite Altona's having the more contami-
nated water source, the rate of cholera deaths in that downstream city was dramatically
lower than in Hamburg. Water filtration, he concluded, was removing the bacteria that
was causing the cholera outbreaks. The early works of Drs. Snow, Pasteur, and Koch
are the foundation of modern water treatment and the protection of public health.
4
With the link to waterborne disease (particularly cholera and typhoid) firmly estab-
lished, improvements to public water supplies were soon to follow. To further study
water filtration in the United States, the Massachusetts State Board of Health estab-
