Tag Archives: mechanical filtration

November 16, 1918: Sanitary Survey of Unnamed City

Privy in terrible condition

November 16, 1918Municipal Journal. A Sanitary Survey of an Unnamed City. The conditions about which you will read were by no means unusual in 1918 in the U.S. “A State Board of Health a few months ago, made a sanitary survey of a certain city (the name of which is unessential) which was of more than usual interest, because of its thoroughness and the sensible recommendations based upon it….

The city in question has a population of about 30,000, of which negroes form a small percentage for a southern city. Although the city is not large, topographical conditions are such as to confine its growth in area, with the result that it presents many of the characteristics of a large, crowded city…. In 1916 fifteen cases of death from typhoid fever were reported, and it is believed that the number was even somewhat greater than this….A comparison of the distribution of the typhoid cases with the wells and privies indicates that the latter have played an important role in the spread of the disease, the typhoid areas largely coinciding with the unsewered districts, without city water. It should be noted further that these “typhoid areas” are located on steep hillsides where the drainage from privy to well is rapid and direct….

The water supply of the city is derived from the river that flows through it, the intake being located at a point near the upper boundary of the city. This river has a water-shed of 1,550 square miles of mountainous and rather thinly populated territory….Examinations of the river for miles upstream have shown its waters to be heavily polluted before they enter the city. While none of the municipal sewers empty into the river above the waterworks intake [thank goodness], there are two small runs draining an extensive unsewered area which is thickly populated….Thus it is seen that the source of supply isalways polluted to a greater or less degree, becoming at times a source of most extreme danger.Only the most thorough filtration and after-treatment can render a water of this character uniformly safe for drinking purposes. Unfortunately the skilled attention that is absolutely essential for the successful operation of a filter plant has not been had until recently.

Purification is secured by coagulation and sedimentation, followed by filtration through so-called mechanical or rapid gravity filters and final treatment with chlorine gas….Just before entering the sedimentation basins, the water receives its dose of coagulant consisting of lime and sulphate of alumina in amounts depending upon the character of the river water as shown by its alkalinity and turbidity….

The man who installed the original hypochlorite plant for final treatment of the water painted its virtues so very bright that he assured the water company that when the river was clear they need not use any chemicals except hypochlorite of lime.It is felt that this ill-advised suggestion may have been in part responsible for the epidemic of typhoid fever the city has just experienced.

The sedimentation basins are two in number, each having a capacity of about 238,000 gallons. At the normal rate of filtration this provides for but one and three-fourths hours storage, a period that is considered far too short to be comparable with adequate coagulation and sedimentation. The control of the chemicals constitutes another objection. The solutions are prepared in large tanks from which they are fed through hand-operated orifices and the rate of dosing is recorded as inches in depth of the tank per hour. Constant-feed, calibrated orifice boxes should be supplied, that the dosing may be more accurately controlled. [see design of such a feed system by George Warren Fuller at the Little Falls treatment plant, Fuller 1903]

From the sedimentation basins the water flows by gravity to the filters, of which there are ten units, each having a superficial area of 230 square feet. At a normal rate of two gallons per square foot a minute, or 125 million gallons per acre per twenty-four hours, the ten units have a combined capacity of about 6.5 million gallons a day. As originally constructed, each unit was provided with a loss-of-head gage, rate controller, and individual sampling pump, all of which equipment has now been dismantled. A loss-of-head gage is essential if accurate knowledge of what each unit is doing and of the proper time to wash is to be had. As it now is, the filter man guessesat the proper time to wash the dirt out of the filter by the position of the inlet float; the dirtier the sand, the higher the level of water on the bed and the more quiet the float—a rather round-about method.

After washing, the filters are allowed to waste for a short time and then turned into the clear well. The lack of any rate controllers on the filters makes it certain that the most recently washed units will be filtering far in excess of the rate for which they were designed. Rate controllers would prevent the units from delivering more than a definite maximum at any time. With as small a clear-well as the one here provided (approximately 37,000 gallons), the lack of this important device becomes even more dangerous in that the pull of the high-service pumps is thrown almost directly upon the filters….

Washing of the filters is effected by forcing water and air through them from below. The water for washing is taken directly from the clear well by an electrically driven centrifugal pump. As has been previously noted, washing cannot be conducted on anything like a scientific basis owing to the lack of loss-of-head gages. The filters are, however, washed at least once a day, and more often if deemed necessary.

From the clear-water well, which is located beneath the filters, the water flows to the high-service pumps, receiving on the way a final treatment with chlorine. Chlorine gas is an excellent sterilizing agent in water, and small doses can effect a remarkable reduction in the number of bacteria present. The chlorine gas is introduced by a direct-feed manual-control chlorinator. In this plant the fact that the dose is not automatically controlled is extremely unfortunate, and if the plant were not in the hands of a skilled filter operator would be a very serious objection….

With a safe and potable water available [forsooth!], there is no excuse for the continuation in use of the 189 private wells in the city. While no analyses have been made to learn the extent to which the wells are polluted, there can be little doubt from their location and construction that many of them are dangerously contaminated.” (emphasis added)

Commentary:  The hard, cold, and alarming facts related in this 1918 sanitary survey of an anonymous southern U.S. city make it quite evident why its identity was not revealed. The typhoid death rate of 50 per 100,000 people in 1916 is shockingly high for a city that is served by a water supply that was both filtered and chlorinated. Obviously, something is terribly wrong with the operation of the treatment plant and the condition of private wells. The person conducting the sanitary survey expressed some optimism about current personnel and operations, but a sanitary survey conducted a year after would be needed to see if that optimism was justified.

The problems related in this sanitary survey should make us all glad that we live in the 21stcentury where we are blessed (at least in developed countries) with safe drinking water supplies.

Reference: “A Sanitary Survey of a City.” 1918. Municipal Journal. 45:19 November 9, 1918, 359-61, 383-6.

November 28, 1837: Birth of John Wesley Hyatt.

November 28, 1837: Birth of John Wesley Hyatt. Hyatt was an inventor who developed new materials and machines that resulted in hundreds of patents. He is mostly known for his invention of a commercially viable way of producing solid, stable nitrocellulose, which he patented in the United States in 1869 as “Celluloid.” However, he was one of the early developers of commercial filtration systems in the U.S. He invented improvements to mechanical filtration systems, which are called rapid sand filters or granular media filters today. During the 1880s, mechanical filters were installed to remove particles and “organic matter.” Filtration to control microbial pathogens would come later with better bacteriological methods and the maturation of the germ theory of disease.

“John Hyatt, an inventor and manufacturer of Newark, N.J., applied for a patent February 11, 1881, on what was virtually a stack of Clark’s filters, placed in a closed tank and operated each independently of the others by means of common supply, delivery and wash pipes. His application, like Clark’s, was granted on June 21, 1881, and assigned to the Newark Filtering Co. On the same day, Hyatt obtained a patent in England.

Col. L. H. Gardner, Superintendent of the New Orleans Water Co., after making small-scale experiments on coagulation at New Orleans, was convinced that it was more efficacious than filtration for the clarification of muddy water.

Isaiah Smith Hyatt, older brother of John, while acting as sales agent for the Newark Filtering Co., was baffled in attempts to clarify Mississippi River water for a New Orleans industrial plant. Colonel Gardner suggested using a coagulant. This was a success. Isaiah Hyatt obtained on February 19, 1884, a patent on simultaneous coagulation-filtration. Although unsound in principle, it largely dominated mechanical filtration for many years….

Thus in 1880-85 did four men join in the evolution of mechanical or rapid filtration. Clark soon faded out of the picture. Gardner entered it only by suggesting to Isaiah Hyatt the use of a coagulant, and Isaiah Hyatt, still a young man, died in March 1885. John Hyatt was then alone. Already he had taken out 20 filter patents while only two were granted to his older brother. By the close of 1889, John had obtained about 50 patents. Scattered grants in the 1890’s brought his record above 60. Most notable of all these were three on washing systems, including sectional wash; several on strainers for underdrain systems; and two on aeration, primarily in connection with filtration. The Hyatt aeration patents, like those granted to Professor Albert R. Leeds a little earlier, were of little practical importance, but they marked an era in water purification during which stress was laid on the removal of organic matter.”

Reference: Baker, Moses N. (1981). The Quest for Pure Water: the History of Water Purification from the Earliest Records to the Twentieth Century. 2nd Edition. Vol. 1. Denver: American Water Works Association, 183-5.

November 16, 1918: Sanitary Survey of Unnamed City

Privy in terrible condition

November 16, 1918Municipal Journal. A Sanitary Survey of an Unnamed City. The conditions about which you will read were by no means unusual in 1918 in the U.S. “A State Board of Health a few months ago, made a sanitary survey of a certain city (the name of which is unessential) which was of more than usual interest, because of its thoroughness and the sensible recommendations based upon it….

The city in question has a population of about 30,000, of which negroes form a small percentage for a southern city. Although the city is not large, topographical conditions are such as to confine its growth in area, with the result that it presents many of the characteristics of a large, crowded city…. In 1916 fifteen cases of death from typhoid fever were reported, and it is believed that the number was even somewhat greater than this….A comparison of the distribution of the typhoid cases with the wells and privies indicates that the latter have played an important role in the spread of the disease, the typhoid areas largely coinciding with the unsewered districts, without city water. It should be noted further that these “typhoid areas” are located on steep hillsides where the drainage from privy to well is rapid and direct….

The water supply of the city is derived from the river that flows through it, the intake being located at a point near the upper boundary of the city. This river has a water-shed of 1,550 square miles of mountainous and rather thinly populated territory….Examinations of the river for miles upstream have shown its waters to be heavily polluted before they enter the city. While none of the municipal sewers empty into the river above the waterworks intake [thank goodness], there are two small runs draining an extensive unsewered area which is thickly populated….Thus it is seen that the source of supply isalways polluted to a greater or less degree, becoming at times a source of most extreme danger.Only the most thorough filtration and after-treatment can render a water of this character uniformly safe for drinking purposes. Unfortunately the skilled attention that is absolutely essential for the successful operation of a filter plant has not been had until recently.

Purification is secured by coagulation and sedimentation, followed by filtration through so-called mechanical or rapid gravity filters and final treatment with chlorine gas….Just before entering the sedimentation basins, the water receives its dose of coagulant consisting of lime and sulphate of alumina in amounts depending upon the character of the river water as shown by its alkalinity and turbidity….

The man who installed the original hypochlorite plant for final treatment of the water painted its virtues so very bright that he assured the water company that when the river was clear they need not use any chemicals except hypochlorite of lime.It is felt that this ill-advised suggestion may have been in part responsible for the epidemic of typhoid fever the city has just experienced.

The sedimentation basins are two in number, each having a capacity of about 238,000 gallons. At the normal rate of filtration this provides for but one and three-fourths hours storage, a period that is considered far too short to be comparable with adequate coagulation and sedimentation. The control of the chemicals constitutes another objection. The solutions are prepared in large tanks from which they are fed through hand-operated orifices and the rate of dosing is recorded as inches in depth of the tank per hour. Constant-feed, calibrated orifice boxes should be supplied, that the dosing may be more accurately controlled. [see design of such a feed system by George Warren Fuller at the Little Falls treatment plant, Fuller 1903]

From the sedimentation basins the water flows by gravity to the filters, of which there are ten units, each having a superficial area of 230 square feet. At a normal rate of two gallons per square foot a minute, or 125 million gallons per acre per twenty-four hours, the ten units have a combined capacity of about 6.5 million gallons a day. As originally constructed, each unit was provided with a loss-of-head gage, rate controller, and individual sampling pump, all of which equipment has now been dismantled. A loss-of-head gage is essential if accurate knowledge of what each unit is doing and of the proper time to wash is to be had. As it now is, the filter man guessesat the proper time to wash the dirt out of the filter by the position of the inlet float; the dirtier the sand, the higher the level of water on the bed and the more quiet the float—a rather round-about method.

After washing, the filters are allowed to waste for a short time and then turned into the clear well. The lack of any rate controllers on the filters makes it certain that the most recently washed units will be filtering far in excess of the rate for which they were designed. Rate controllers would prevent the units from delivering more than a definite maximum at any time. With as small a clear-well as the one here provided (approximately 37,000 gallons), the lack of this important device becomes even more dangerous in that the pull of the high-service pumps is thrown almost directly upon the filters….

Washing of the filters is effected by forcing water and air through them from below. The water for washing is taken directly from the clear well by an electrically driven centrifugal pump. As has been previously noted, washing cannot be conducted on anything like a scientific basis owing to the lack of loss-of-head gages. The filters are, however, washed at least once a day, and more often if deemed necessary.

From the clear-water well, which is located beneath the filters, the water flows to the high-service pumps, receiving on the way a final treatment with chlorine. Chlorine gas is an excellent sterilizing agent in water, and small doses can effect a remarkable reduction in the number of bacteria present. The chlorine gas is introduced by a direct-feed manual-control chlorinator. In this plant the fact that the dose is not automatically controlled is extremely unfortunate, and if the plant were not in the hands of a skilled filter operator would be a very serious objection….

With a safe and potable water available [forsooth!], there is no excuse for the continuation in use of the 189 private wells in the city. While no analyses have been made to learn the extent to which the wells are polluted, there can be little doubt from their location and construction that many of them are dangerously contaminated.” (emphasis added)

Commentary:  The hard, cold, and alarming facts related in this 1918 sanitary survey of an anonymous southern U.S. city make it quite evident why its identity was not revealed. The typhoid death rate of 50 per 100,000 people in 1916 is shockingly high for a city that is served by a water supply that was both filtered and chlorinated. Obviously, something is terribly wrong with the operation of the treatment plant and the condition of private wells. The person conducting the sanitary survey expressed some optimism about current personnel and operations, but a sanitary survey conducted a year after would be needed to see if that optimism was justified.

The problems related in this sanitary survey should make us all glad that we live in the 21stcentury where we are blessed (at least in developed countries) with safe drinking water supplies.

Reference: “A Sanitary Survey of a City.” 1918. Municipal Journal. 45:19 November 9, 1918, 359-61, 383-6.

November 28, 1837: Birth of John Wesley Hyatt.

November 28, 1837: Birth of John Wesley Hyatt. Hyatt was an inventor who developed new materials and machines that resulted in hundreds of patents. He is mostly known for his invention of a commercially viable way of producing solid, stable nitrocellulose, which he patented in the United States in 1869 as “Celluloid.” However, he was one of the early developers of commercial filtration systems in the U.S. He invented improvements to mechanical filtration systems, which are called rapid sand filters or granular media filters today. During the 1880s, mechanical filters were installed to remove particles and “organic matter.” Filtration to control microbial pathogens would come later with better bacteriological methods and the maturation of the germ theory of disease.

“John Hyatt, an inventor and manufacturer of Newark, N.J., applied for a patent February 11, 1881, on what was virtually a stack of Clark’s filters, placed in a closed tank and operated each independently of the others by means of common supply, delivery and wash pipes. His application, like Clark’s, was granted on June 21, 1881, and assigned to the Newark Filtering Co. On the same day, Hyatt obtained a patent in England.

Col. L. H. Gardner, Superintendent of the New Orleans Water Co., after making small-scale experiments on coagulation at New Orleans, was convinced that it was more efficacious than filtration for the clarification of muddy water.

Isaiah Smith Hyatt, older brother of John, while acting as sales agent for the Newark Filtering Co., was baffled in attempts to clarify Mississippi River water for a New Orleans industrial plant. Colonel Gardner suggested using a coagulant. This was a success. Isaiah Hyatt obtained on February 19, 1884, a patent on simultaneous coagulation-filtration. Although unsound in principle, it largely dominated mechanical filtration for many years….

Thus in 1880-85 did four men join in the evolution of mechanical or rapid filtration. Clark soon faded out of the picture. Gardner entered it only by suggesting to Isaiah Hyatt the use of a coagulant, and Isaiah Hyatt, still a young man, died in March 1885. John Hyatt was then alone. Already he had taken out 20 filter patents while only two were granted to his older brother. By the close of 1889, John had obtained about 50 patents. Scattered grants in the 1890’s brought his record above 60. Most notable of all these were three on washing systems, including sectional wash; several on strainers for underdrain systems; and two on aeration, primarily in connection with filtration. The Hyatt aeration patents, like those granted to Professor Albert R. Leeds a little earlier, were of little practical importance, but they marked an era in water purification during which stress was laid on the removal of organic matter.”

Reference: Baker, Moses N. (1981). The Quest for Pure Water: the History of Water Purification from the Earliest Records to the Twentieth Century. 2nd Edition. Vol. 1. Denver: American Water Works Association, 183-5.

November 16, 1918: Sanitary Survey of Unnamed City

Privy in terrible condition

November 16, 1918Municipal Journal. A Sanitary Survey of an Unnamed City. The conditions about which you will read were by no means unusual in 1918 in the U.S. “A State Board of Health a few months ago, made a sanitary survey of a certain city (the name of which is unessential) which was of more than usual interest, because of its thoroughness and the sensible recommendations based upon it….

The city in question has a population of about 30,000, of which negroes form a small percentage for a southern city. Although the city is not large, topographical conditions are such as to confine its growth in area, with the result that it presents many of the characteristics of a large, crowded city…. In 1916 fifteen cases of death from typhoid fever were reported, and it is believed that the number was even somewhat greater than this…. A comparison of the distribution of the typhoid cases with the wells and privies indicates that the latter have played an important role in the spread of the disease, the typhoid areas largely coinciding with the unsewered districts, without city water. It should be noted further that these “typhoid areas” are located on steep hillsides where the drainage from privy to well is rapid and direct….

The water supply of the city is derived from the river that flows through it, the intake being located at a point near the upper boundary of the city. This river has a water-shed of 1,550 square miles of mountainous and rather thinly populated territory….Examinations of the river for miles upstream have shown its waters to be heavily polluted before they enter the city. While none of the municipal sewers empty into the river above the waterworks intake [thank goodness], there are two small runs draining an extensive unsewered area which is thickly populated….Thus it is seen that the source of supply is always polluted to a greater or less degree, becoming at times a source of most extreme danger. Only the most thorough filtration and after-treatment can render a water of this character uniformly safe for drinking purposes. Unfortunately the skilled attention that is absolutely essential for the successful operation of a filter plant has not been had until recently.

Purification is secured by coagulation and sedimentation, followed by filtration through so-called mechanical or rapid gravity filters and final treatment with chlorine gas….Just before entering the sedimentation basins, the water receives its dose of coagulant consisting of lime and sulphate of alumina in amounts depending upon the character of the river water as shown by its alkalinity and turbidity….

The man who installed the original hypochlorite plant for final treatment of the water painted its virtues so very bright that he assured the water company that when the river was clear they need not use any chemicals except hypochlorite of lime. It is felt that this ill-advised suggestion may have been in part responsible for the epidemic of typhoid fever the city has just experienced.

The sedimentation basins are two in number, each having a capacity of about 238,000 gallons. At the normal rate of filtration this provides for but one and three-fourths hours storage, a period that is considered far too short to be comparable with adequate coagulation and sedimentation. The control of the chemicals constitutes another objection. The solutions are prepared in large tanks from which they are fed through hand-operated orifices and the rate of dosing is recorded as inches in depth of the tank per hour. Constant-feed, calibrated orifice boxes should be supplied, that the dosing may be more accurately controlled. [see design of such a feed system by George Warren Fuller at the Little Falls treatment plant, Fuller 1903]

From the sedimentation basins the water flows by gravity to the filters, of which there are ten units, each having a superficial area of 230 square feet. At a normal rate of two gallons per square foot a minute, or 125 million gallons per acre per twenty-four hours, the ten units have a combined capacity of about 6.5 million gallons a day. As originally constructed, each unit was provided with a loss-of-head gage, rate controller, and individual sampling pump, all of which equipment has now been dismantled. A loss-of-head gage is essential if accurate knowledge of what each unit is doing and of the proper time to wash is to be had. As it now is, the filter man guesses at the proper time to wash the dirt out of the filter by the position of the inlet float; the dirtier the sand, the higher the level of water on the bed and the more quiet the float—a rather round-about method.

After washing, the filters are allowed to waste for a short time and then turned into the clear well. The lack of any rate controllers on the filters makes it certain that the most recently washed units will be filtering far in excess of the rate for which they were designed. Rate controllers would prevent the units from delivering more than a definite maximum at any time. With as small a clear-well as the one here provided (approximately 37,000 gallons), the lack of this important device becomes even more dangerous in that the pull of the high-service pumps is thrown almost directly upon the filters….

Washing of the filters is effected by forcing water and air through them from below. The water for washing is taken directly from the clear well by an electrically driven centrifugal pump. As has been previously noted, washing cannot be conducted on anything like a scientific basis owing to the lack of loss-of-head gages. The filters are, however, washed at least once a day, and more often if deemed necessary.

From the clear-water well, which is located beneath the filters, the water flows to the high-service pumps, receiving on the way a final treatment with chlorine. Chlorine gas is an excellent sterilizing agent in water, and small doses can effect a remarkable reduction in the number of bacteria present. The chlorine gas is introduced by a direct-feed manual-control chlorinator. In this plant the fact that the dose is not automatically controlled is extremely unfortunate, and if the plant were not in the hands of a skilled filter operator would be a very serious objection….

With a safe and potable water available [forsooth!], there is no excuse for the continuation in use of the 189 private wells in the city. While no analyses have been made to learn the extent to which the wells are polluted, there can be little doubt from their location and construction that many of them are dangerously contaminated.” (emphasis added)

Commentary:  The hard, cold, and alarming facts related in this 1918 sanitary survey of an anonymous southern U.S. city make it quite evident why its identity was not revealed. The typhoid death rate of 50 per 100,000 people in 1916 is shockingly high for a city that is served by a water supply that was both filtered and chlorinated. Obviously, something is terribly wrong with the operation of the treatment plant and the condition of private wells. The person conducting the sanitary survey expressed some optimism about current personnel and operations, but a sanitary survey conducted a year after would be needed to see if that optimism was justified.

The problems related in this sanitary survey should make us all glad that we live in the 21st century where we are blessed (at least in developed countries) with safe drinking water supplies.

Reference:  “A Sanitary Survey of a City.” 1918. Municipal Journal. 45:19 November 9, 1918, 359-61, 383-6.

November 28, 1837: Birth of John Wesley Hyatt.

1128 John W HyattNovember 28, 1837: Birth of John Wesley Hyatt. Hyatt was an inventor who developed new materials and machines that resulted in hundreds of patents. He is mostly known for his invention of a commercially viable way of producing solid, stable nitrocellulose, which he patented in the United States in 1869 as “Celluloid.” However, he was one of the early developers of commercial filtration systems in the U.S. He invented improvements to mechanical filtration systems, which are called rapid sand filters or granular media filters today. During the 1880s, mechanical filters were installed to remove particles and “organic matter.” Filtration to control microbial pathogens would come later with better bacteriological methods and the maturation of the germ theory of disease.

“John Hyatt, an inventor and manufacturer of Newark, N.J., applied for a patent February 11, 1881, on what was virtually a stack of Clark’s filters, placed in a closed tank and operated each independently of the others by means of common supply, delivery and wash pipes. His application, like Clark’s, was granted on June 21, 1881, and assigned to the Newark Filtering Co. On the same day, Hyatt obtained a patent in England.

Col. L. H. Gardner, Superintendent of the New Orleans Water Co., after making small-scale experiments on coagulation at New Orleans, was convinced that it was more efficacious than filtration for the clarification of muddy water.

Isaiah Smith Hyatt, older brother of John, while acting as sales agent for the Newark Filtering Co., was baffled in attempts to clarify Mississippi River water for a New Orleans industrial plant. Colonel Gardner suggested using a coagulant. This was a success. Isaiah Hyatt obtained on February 19, 1884, a patent on simultaneous coagulation-filtration. Although unsound in principle, it largely dominated mechanical filtration for many years….

Thus in 1880-85 did four men join in the evolution of mechanical or rapid filtration. Clark soon faded out of the picture. Gardner entered it only by suggesting to Isaiah Hyatt the use of a coagulant, and Isaiah Hyatt, still a young man, died in March 1885. John Hyatt was then alone. Already he had taken out 20 filter patents while only two were granted to his older brother. By the close of 1889, John had obtained about 50 patents. Scattered grants in the 1890’s brought his record above 60. Most notable of all these were three on washing systems, including sectional wash; several on strainers for underdrain systems; and two on aeration, primarily in connection with filtration. The Hyatt aeration patents, like those granted to Professor Albert R. Leeds a little earlier, were of little practical importance, but they marked an era in water purification during which stress was laid on the removal of organic matter.”

Reference: Baker, Moses N. (1981). The Quest for Pure Water: the History of Water Purification from the Earliest Records to the Twentieth Century. 2nd Edition. Vol. 1. Denver: American Water Works Association, 183-5.

1128 Hyatt Pure Water  Filter

November 16, 1918: Sanitary Survey of Unnamed City

Privy in terrible condition

Privy in terrible condition

November 16, 1918: Municipal Journal. A Sanitary Survey of an Unnamed City. The conditions about which you will read were by no means unusual in 1918 in the U.S. “A State Board of Health a few months ago, made a sanitary survey of a certain city (the name of which is unessential) which was of more than usual interest, because of its thoroughness and the sensible recommendations based upon it….

The city in question has a population of about 30,000, of which negroes form a small percentage for a southern city. Although the city is not large, topographical conditions are such as to confine its growth in area, with the result that it presents many of the characteristics of a large, crowded city…. In 1916 fifteen cases of death from typhoid fever were reported, and it is believed that the number was even somewhat greater than this…. A comparison of the distribution of the typhoid cases with the wells and privies indicates that the latter have played an important role in the spread of the disease, the typhoid areas largely coinciding with the unsewered districts, without city water. It should be noted further that these “typhoid areas” are located on steep hillsides where the drainage from privy to well is rapid and direct….

The water supply of the city is derived from the river that flows through it, the intake being located at a point near the upper boundary of the city. This river has a water-shed of 1,550 square miles of mountainous and rather thinly populated territory….Examinations of the river for miles upstream have shown its waters to be heavily polluted before they enter the city. While none of the municipal sewers empty into the river above the waterworks intake [thank goodness], there are two small runs draining an extensive unsewered area which is thickly populated….Thus it is seen that the source of supply is always polluted to a greater or less degree, becoming at times a source of most extreme danger. Only the most thorough filtration and after-treatment can render a water of this character uniformly safe for drinking purposes. Unfortunately the skilled attention that is absolutely essential for the successful operation of a filter plant has not been had until recently.

Purification is secured by coagulation and sedimentation, followed by filtration through so-called mechanical or rapid gravity filters and final treatment with chlorine gas….Just before entering the sedimentation basins, the water receives its dose of coagulant consisting of lime and sulphate of alumina in amounts depending upon the character of the river water as shown by its alkalinity and turbidity….

The man who installed the original hypochlorite plant for final treatment of the water painted its virtues so very bright that he assured the water company that when the river was clear they need not use any chemicals except hypochlorite of lime. It is felt that this ill-advised suggestion may have been in part responsible for the epidemic of typhoid fever the city has just experienced.

The sedimentation basins are two in number, each having a capacity of about 238,000 gallons. At the normal rate of filtration this provides for but one and three-fourths hours storage, a period that is considered far too short to be comparable with adequate coagulation and sedimentation. The control of the chemicals constitutes another objection. The solutions are prepared in large tanks from which they are fed through hand-operated orifices and the rate of dosing is recorded as inches in depth of the tank per hour. Constant-feed, calibrated orifice boxes should be supplied, that the dosing may be more accurately controlled. [see design of such a feed system by George Warren Fuller at the Little Falls treatment plant, Fuller 1903]

From the sedimentation basins the water flows by gravity to the filters, of which there are ten units, each having a superficial area of 230 square feet. At a normal rate of two gallons per square foot a minute, or 125 million gallons per acre per twenty-four hours, the ten units have a combined capacity of about 6.5 million gallons a day. As originally constructed, each unit was provided with a loss-of-head gage, rate controller, and individual sampling pump, all of which equipment has now been dismantled. A loss-of-head gage is essential if accurate knowledge of what each unit is doing and of the proper time to wash is to be had. As it now is, the filter man guesses at the proper time to wash the dirt out of the filter by the position of the inlet float; the dirtier the sand, the higher the level of water on the bed and the more quiet the float—a rather round-about method.

After washing, the filters are allowed to waste for a short time and then turned into the clear well. The lack of any rate controllers on the filters makes it certain that the most recently washed units will be filtering far in excess of the rate for which they were designed. Rate controllers would prevent the units from delivering more than a definite maximum at any time. With as small a clear-well as the one here provided (approximately 37,000 gallons), the lack of this important device becomes even more dangerous in that the pull of the high-service pumps is thrown almost directly upon the filters….

Washing of the filters is effected by forcing water and air through them from below. The water for washing is taken directly from the clear well by an electrically driven centrifugal pump. As has been previously noted, washing cannot be conducted on anything like a scientific basis owing to the lack of loss-of-head gages. The filters are, however, washed at least once a day, and more often if deemed necessary.

From the clear-water well, which is located beneath the filters, the water flows to the high-service pumps, receiving on the way a final treatment with chlorine. Chlorine gas is an excellent sterilizing agent in water, and small doses can effect a remarkable reduction in the number of bacteria present. The chlorine gas is introduced by a direct-feed manual-control chlorinator. In this plant the fact that the dose is not automatically controlled is extremely unfortunate, and if the plant were not in the hands of a skilled filter operator would be a very serious objection….

With a safe and potable water available [forsooth!], there is no excuse for the continuation in use of the 189 private wells in the city. While no analyses have been made to learn the extent to which the wells are polluted, there can be little doubt from their location and construction that many of them are dangerously contaminated.” (emphasis added)

Commentary: The hard, cold, and alarming facts related in this 1918 sanitary survey of an anonymous southern U.S. city make it quite evident why its identity was not revealed. The typhoid death rate of 50 per 100,000 people in 1916 is shockingly high for a city that is served by a water supply that was both filtered and chlorinated. Obviously, something is terribly wrong with the operation of the treatment plant and the condition of private wells. The person conducting the sanitary survey expressed some optimism about current personnel and operations, but a sanitary survey conducted a year after would be needed to see if that optimism was justified.

The problems related in this sanitary survey should make us all glad that we live in the 21st century where we are blessed (at least in developed countries) with safe drinking water supplies.

Reference: “A Sanitary Survey of a City.” 1918. Municipal Journal. 45:19 November 9, 1918, 359-61, 383-6.