Tag Archives: water history

January 14, 1973: First Recorded Typhoid Case in South Florida Outbreak; 1829: First Slow Sand Filter in England

5/13/1976, Roy Bartley/Miami Herald: Everglades farm labor camp 19400 SW 376th St.

January 14, 1973:  First Recorded Typhoid Case in South Florida Outbreak.The last major recorded epidemic of typhoid fever in the United States occurred in Manteno State Hospital, Illinois, in 1939. There were 453 cases, with 60 deaths. Sanitation procedures generally have been improved markedly since that time, but despite such improvement the South Dade Labor Camp near Homestead, Florida, developed a sizable outbreak early in 1973 (172 hospitalized, 38 not hospitalized,no deaths).

Intensive investigation of the water supply and of the sewage system was begun immediately. A number of suspicious findings  were observed. These systems had originally been installed about 1940, and were replaced in 1969. The water  was supplied from  two wells. The first suspicious finding  was that these wells were reported at first to be 50 feet deep with 38 feet of casing. The well driller’s job log confirmed these depths. By sounding, however,  an approximate depth of 20 feet was discovered. Later in our studies,  we noted that the certificate provided by the state’s Sanitary Engineering office had approved the 20 foot depth.

Second, in the center of the well house was a floor drain connected to an outside dry well surrounded by a vitreous clay pipe. When fluorescent dye was introduced into this well, it appeared in the water supply in 3 1/2 min.

Third, dye was also painted on the ground about 10 feet from the water wells. In less than 15 min, the dye appeared in the water.

Fourth, several holes were dug in the area of the well house. The old sewer system, abandoned in 1969, but close to the origin of the water supply, was found to contain human feces, as evidenced by the recovery of Salmonella saint-paul.

Fifth, inspection of the character of the ground revealed many solution channels in the area surrounding the wells.

Sixth, about 100 yards from the wells was a common toilet facility. Immediately outside this facility was a grease trap, connected only to the sinks. Upon emptying the trap, human feces were found in it.

Seventh, about 1000 feet away from the wells was a 50,000-gallon storage tank. This tank was cleaned and found to contain beer cans, bottles, other rubbish, and feces.

Commentary:  I guess that there is no real surprise that there was a typhoid outbreak in this labor camp given all of the sanitary defects in the water and wastewater systems. Remember, this typhoid outbreak occurred in 1973. 1973!

January 14, 1829:  The first slow sand filter in England was put into operation by James Simpson. “Best known of all the filtration pioneers is James Simpson. He was born July 25, 1799, at the official residence of his father, who was Inspector General (engineer) of the Chelsea Water Works Co. The house was on the north bank of the Thames, near the pumping station and near what was to become the site of the filter that was copied the world over. At the early age of 24, James Simpson was appointed Inspector (engineer) of the water company at a salary of £300 a year, after having acted in that capacity for a year and a half during the illness of his father. At 26, he was elected to the recently created Institution of Civil Engineers. At 28, he made his 2,000-mile inspection trip to Manchester, Glasgow and other towns in the North, after designing the model for a working-scale filter to be executed in his absence. On January 14, 1829, when Simpson was in his thirtieth year, the one-acre filter at Chelsea commonly known as the first English slow sand filter, was put into operation….

Skepticism as to the wholesomeness of filtered water in 1828 and Simpson’s reassurances on the subject are amusing today. At the hearing before the Royal Commission a member asked whether any persons had been in the habit of drinking the water filtered on a small scale. ‘Yes,’ answered Simpson. Had they complained of the water ‘being insalubrious, giving them cholic or any other complaints?’ To this, the engineer replied that none of the more than 100 men working on the ground (presumably on the permanent filter) had complained of the filtered water…Fish, the commission was assured, did not die in the filtered water.Simpson willingly admitted that ‘water may contain so many ingredients chemically dissolved, that filtration will not purify it.’ Asked whether the discharge from King’s Scholars Sewer could be ‘so filtered as to be fit to drink,’ Simpson cannily said he had never tried it. Asked whether filtration would remove bad taste from water, Simpson replied that ‘Thames water has a taste according to season, of animal and vegetable matter’; filtration ‘seems to deprive it of the whole of that, and we cannot discover it after it has passed the bed.’”

Commentary:  It is a good thing that fish did not die in the filtered water. That would have been the end of the sanitary engineering profession.

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, Co.: American Water Works Association, 99, 109.

Advertisements

January 12, 1933: Drought Cartoon; 1987: Cryptosporidiosis Outbreak in Georgia; 1870: Birth of Edward Bartow

January 12, 1933:  Drought Cartoon. The Los Angeles Times has published cartoons over more than 100 years that depict the many droughts that California has suffered and the reactions to them. Here is one that I think you will enjoy.

Cryptosporidium oocysts on an intestinal cell surface, S.E.M.
Image courtesy of Dr. Udo Hertzel,Verterinary Pathology, University of Liverpool

January 12, 1987:  A large outbreak of cryptosporidiosis began on this day.“Between January 12 and February 7, 1987, an outbreak of gastroenteritis affected an estimated 13,000 (out of 64,900) people in Carroll County in western Georgia (including Carrollton, GA). Cryptosporidiumoocysts were identified in the stools of 58 of 147 patients with gastroenteritis (39 percent) tested during the outbreak. Studies for bacterial, viral, and other parasitic pathogens failed to implicate any other agent. In a random telephone survey, 299 of 489 household members exposed to the public water supply (61 percent) reported gastrointestinal illness, as compared with 64 of 322 (20 percent) who were not exposed (relative risk, 3.1; 95 percent confidence interval, 2.4 to 3.9). The prevalence of IgG [Immunoglobulin G—an antibody isotype] to Cryptosporidiumwas significantly higher among exposed respondents to the survey who had become ill than among nonresident controls. Cryptosporidiumoocysts were identified in samples of treated public water with use of a monoclonal-antibody test. Although the sand-filtered and chlorinated water system met all regulatory-agency quality standards, sub-optimal flocculation and filtration probably allowed the parasite to pass into the drinking-water supply. Low-level Cryptosporidiuminfection in cattle in the watershed and a sewage overflow were considered as possible contributors to the contamination of the surface-water supply. We conclude that current standards for the treatment of public water supplies may not prevent the contamination of drinking water by Cryptosporidium, with consequent outbreaks of cryptosporidiosis.”

A single Cryptosporidium oocyst

Commentary: This outbreak caused a lot of concern in the drinking water community, but it was the epidemic of cryptosporidiosis in Milwaukee in April six years later that drove the second phase of the enhanced surface water treatment rule.

Reference:  Hayes, E.B. et al. 1989. “Large community outbreak of cryptosporidiosis due to contamination of a filtered public water supply.” N. Engl J Med. 320:21(May 25): 1372-6.

January 12, 1870:  Edward Bartow was born.“Edward Bartow (1870–1958) was an American chemist and an expert in the field of sanitary chemistry. His career extended from 1897 to 1958 and he is best known for his work in drinking water purification and wastewater treatment. He was well known as an educator, and his many students went on to leadership positions in the fields of sanitary chemistry and engineering….

He began his career as an instructor of chemistry at Williams College about 1896. His first academic appointment was as an assistant professor of chemistry at the University of Kansas. He taught there from 1897 to 1905. While in Kansas, he worked with the U.S. Geological Survey analyzing the waters of southeastern part of the state.

His next position was as Director of the Illinois State Water Survey. He also held the title of professor of sanitary chemistry at the University of Illinois from 1905 to 1920. He led efforts to eliminate typhoid fever by developing treatment methodologies for water purification. In 1914, he began the first large-scale investigations of the new sewage treatment process called activated sludge. A bronze plaque was placed on the grounds of the Champaign-Urbana Sanitary District to commemorate the work on this process done by Bartow and his colleagues. The Illinois State Water Survey became well known for producing high quality work and the fourteen volumes of bulletins and reports published during his tenure are classics in the field of sanitary chemistry and engineering.

From 1920 until his retirement in 1940, he was professor of chemistry at the University of Iowa. He significantly enhanced the department and when he left, the number of PhD degrees awarded totaled 240 in chemistry and chemical engineering….

Bartow received many honors including an honorary D.Sc. from Williams College in 1923. Several societies honored him with life memberships. In 1971, he was inducted into the American Water Works Association Water Industry Hall of Fame.”

January 11, 1922: Chlorination of New England water supplies and Demands for Lower Color Content of Drinking Water

January 11, 1922:  Two fascinating articles in Engineering and Contractingabout the progress of water treatment, regulations and disinfection in U.S. water supplies in 1922.

“The Chlorination of New England Water Supplies.” By William J. Orchard. “One thousand nine hundred and ninety-six: communities In the United States chlorinate water or sewage or both with liquid chlorine. Only 128 or 6 per cent of these are in New England. Twelve are treating sewage, leaving but 116 New England communities chlorinating drinking water. Nearly half, 43 per cent, of these are in Connecticut where 51 communities use liquid chlorine to safeguard their water supplies, 24 are in Maine, 16 are in New Hampshire, 11 in Rhode Island, Massachusetts has nine while Vermont has three communities using liquid chlorine for their water supplies.

Scoring the states in this country in accordance with the number of communities using liquid chlorine and starting with New York in first place with 254, ending with Nevada in 48th place with but one lone chlorinating community we find Connecticut stands 11th, Maine 25th, New Hampshire 30th, Rhode Island 36th, Massachusetts 41st, and Vermont 47th.

A manufacturer of chlorinating equipment naturally asks why this relatively small number of communities using liquid chlorine in certain sections of New England? Now, in trying to answer that question, the speaker appreciates that he is skating on thin ice-dangerously near a deep hole labeled ‘The Johnsonian Controversy,’ and caution dictates that he skate the other way.

But it is a fact that there is more resistance to the chlorination of drinking water in New England than in any other section of the country. Some of this is due to a firm, honest conviction in the purity and safety of unsterilized water supplies-some of this is due to complete deep rooted faith in the absolute efficacy of storage and water shed patrol—but, in the writer’s opinion, the principle cause for this resistance to chlorination in New England Is the marked aversion found In some quarters to the application of chemicals in any form to drinking water. It matters not if, as in the case of sterilization, a barrel full of chlorine will suffice for a Woolworth building filled with water. The objection is to the application of chemicals in any form-no matter what the chemicals may be. This attitude was clearly expressed by one of New England’s most prominent engineers who said to the speaker, ‘Up here we don’t want medicated waters.’”

Commentary: I am not sure what “The Johnsonian Controversy” was but Orchard correctly points out the resistance to chlorination in New England. Antagonism against the use of chemicals in drinking water treatment was, in large part, due to the influence of the Lawrence Experiment Station on the actions of water plants.

Engineering and Contractingarticle. “Some Features of Present Water Supply Practice.” Nicholas S. Hill, Chairman. “Water Quality Standards—Standards of quality are steadily rising and bid fair to continue doing so. Communities no longer consider safety sufficient, but demand a drinking water of good appearance. This demand has good scientific foundation for the best appearing waters are frequently the safer.

In certain sections, the northeast particularly, waters having colors of 25 or more are still used without complaint.  These colors would not be tolerated in western cities supplied with lake or filtered river water, or even in New England. Public opinion is fast getting in a position to demand water of an average color of 10 parts per million or less with a maximum of 15. Particular objection is made to colored surface waters containing odoriferous organisms and turbidity, whether due to heavy microscopic growths, to clay, or to iron rust, is also objectionable.

While the bacteriological standard of the U. S. Public Health Service [1914] met with considerable criticism because of its alleged severity and because it excluded certain water supplying communities in which good public health conditions prevailed. It can not be denied that those who are aiming to supply waters of high quality are trying to equal or better this standard which, as is well known, commands that all waters used in inter-state commerce shall contain no gas-forming organisms (presumably B. coli) in at least three out of five portions of 10 c.c. from the sample tested. One reason for this appreciation is the improvement in public health diagnosis; this, in turn, to better vital statistics, better organization of the health authorities and refinements in clinical methods.”

Commentary: Only 14 years after chlorination began to eradicate waterborne disease, an enlightened public began to demand higher quality water—as they should.

Reference:  Engineering and Contracting. 1922. 57:2(January 11, 1922): 22-3.

January 10, 1983: Wards Island Dumps Sewage

January 10, 1983:  New York Times headline—Repair of Plant Ends Dumping of Raw Sewage. “The Wards Island sewage treatment plant, disabled when a huge valve burst six days ago, was back in operation yesterday, ending the daily discharge of 300 million gallons of raw sewage into the Harlem, Hudson and East Rivers.

The city had been forced to divert the sewage from the plant after a ”cone check valve” cracked at 8:30 P.M. on Tuesday, sent a 12-foot jet of water into the air and caused the flooding of the plant’s six main motors….

The total cost of fixing the plant will be about $330,000, according to John Cunningham, a spokesman for the city’s Department of Environmental Protection….

‘All the charts, the records, the work schedules went by the wayside,’ said Fred DiSisto, an operating engineer with the plant for 20 years. ‘We operated out of the kitchen. It kind of turned into a holiday atmosphere. Everybody was all pumped up. It broke the routine around here.’

Some of the men at the plant estimate that 50 pounds of coffee were consumed in the kitchen in the last four days. Men slept there, too, as 12-hour shifts were the norm.

Officials have not yet determined what caused the cone check valve to burst. The valve is made of cast iron and is 48 inches in diameter. It was installed six years ago, when the 45-year-old plant was upgraded.

‘We are still doing some tests to find out why the valve broke,’ said Mr. Cunningham. ‘The valve should have lasted 40 years.’ The valve is one of six that keeps the waste water in the plant’s treatment tanks from flowing back into the plant’s main pumping gallery. When it burst, the water came back into the gallery and then overflowed onto the plant’s motors. Released Into Rivers

The sewage had to be released into the Hudson, Harlem and East Rivers from 52 regulators in Manhattan and 36 regulators in the Bronx to avoid a backup at the plant and the eventual flooding of homes, officials said.”

TDIWH—January 9, 2014: MCHM Chemical Spill in West Virginia; 1985: Plane Crashes into Kansas Water Treatment Plant; 2012: First Haitian Cholera Victim; 1997: Water is Still Deadly Drink in Parts of the World

Middle Tank (#396) was the source of most of MCHM spill

January 9, 2014:  MCHM Chemical Spill in West Virginia. “Charleston, WV; January 9, 2014. 7:46AM. You’re trying to get your children up, fix breakfast and get them ready for school. You stick your head out the door to see how cold it is, and a wave of something smelling like black licorice hits you. The Elk River below you seems fine, but that odor is rolling off the surface. None of the radio news stations are saying anything. Wait. You know where your water comes from-the Elk River. Is the drinking water safe? You call the water department to find out what’s going on.

Sounding the Alarm: Do Not Use!

So began the day for 300,000 people in Charleston, West Virginia and in the surrounding nine counties. A tweet from Gov. Earl Ray Tomblin at 2:36 PM on January 9 previewed the 5:45 pm press conference where a Do Not Use order was issued by West Virginia American Water (WVAW) for all of the water in their service area. (A Do Not Use order is the most serious warning that can be given for drinking water. It means that tap water can only be used for flushing toilets and fighting fires.) At the press conference, the governor declared a state of emergency for the affected area.

It later became clear that a spill of about 10,000 gallons of something called Crude MCHM took place at a Freedom Industries facility 1.5 miles above the intake of the Kanawha Valley Water Treatment Plant (KVWTP), which is run by WVAW. When the spill actually occurred and when the material entered the water treatment plant has not been determined at this writing. The maximum MCHM concentration measured in the influent to the plant was about 3.4 mg/1. No one has adequately explained why the plant intake was not shut down early on January 9.

By 7 PM on January 9 a full-blown water-buying panic had gripped the area. Cases of bottled water were stripped from shelves within a 20-mile radius of Charleston. The morning of January 10, President Obama declared the nine counties a federal disaster area.”

Reference:  McGuire, M.J., 2014. “The West Virginia Chemical Spill: A Massive Loss in Public Confidence.” Source. CA NV Section AWWA,28:3:31 Summer.

January 9, 1985:  Plane crashes into Kansas water treatment plant. “Last January the Board of Public Works (BPU) of Kansas City, Kansas was the victim of an airplane crash at their Quindaro water treatment plant complex. Although all members of the airplane’s crew were killed, the members of the BPU operations staff on duty that morning were unharmed, although shook up. The airplane managed to miss two nearby power plant structures, the east side of the treatment plant, and the chemical treatment plant building where the four employees were working, but landed in a primary basin less than 50 feet away from the building. An intensive manpower effort was launched to get the debris cleaned up and the plant back in operation as soon as possible. Three weeks to the day after the crash, the basin without a walkway bridge was returned to service. Kermit

Mangum, the water plant superintendent, is scheduled to talk about this story at the KSAWWA conference in Wichita.”

Commentary:  Thanks to Paul Crocker of the Kansas City BPU for providing this information.

Map: Distribution of cholera cases in Haiti

January 9, 2012:  New York Times headline—Haiti: Cholera Epidemic’s First Victim Identified as River Bather Who Forsook Clean Water. “The first Haitian to get cholera at the onset of the 2010 epidemic was almost undoubtedly a 28-year-old mentally disturbed man from the town of Mirebalais, researchers reported Monday.

The man, whose name was not revealed in the report, in The American Journal of Tropical Medicine and Hygiene, was known as the village “moun fou” — Creole for “crazy person” — said the authors, who work for Partners in Health, a Boston group associated with Dr. Paul E. Farmer that has provided free health care in Haiti since 1987.

Although his family had clean drinking water, the man often walked naked through town to bathe and drink from the Latem River just downstream from the Meye River, into which raw sewage drained from an encampment of United Nations peacekeepers from Nepal.

Haiti’s outbreak was of a Nepali strain, and that encampment is considered the source.

The man developed severe diarrhea on Oct. 12, 2010, and died in less than 24 hours. Two people who washed his body for a wake fell ill 48 hours later. Haiti’s first hospitalized cholera case was in Mirebalais on Oct. 17.

The epidemic has since sickened nearly 500,000 people across Haiti and killed nearly 7,000.”

Commentary:  The death toll is now about 10,000 with no end in sight. The UN finally took some responsibility for starting the epidemic. It was caused by poor sanitation habits of Nepalese soldiers who were stationed in Haiti to aid in recovery from the devastating earthquake.

The most effective treatment for cholera is intravenous hydration.

January 9, 1997:  New York Times headline— For Third World, Water Is Still a Deadly Drink. By Nicholas Kristof “THANE, India— Children like the Bhagwani boys scamper about barefoot on the narrow muddy paths that wind through the labyrinth of a slum here, squatting and relieving themselves as the need arises, as casual about the filth as the bedraggled rats that nose about in the raw sewage trickling beside the paths.

Parents, like Usha Bhagwani, a rail-thin 28-year-old housemaid, point out their children and fret about how to spend their rupees. Should they buy good food so that the children will get stronger? Or should they buy shoes so that the children will not get hookworms? Or should they send their sons and daughters to school? Or should they buy kerosene to boil the water?

There is not enough money for all of those needs, so parents must choose. It was to save money, as well as to save time, that Mrs. Bhagwani was serving unboiled water the other day to her 5- and 7-year-old boys in her one-room hovel. Her bony face and sharp eyes softened as she watched them take the white plastic cup and gulp the deadly drink.

The water has already killed two of her children, a 15-month-old, Santosh, a boy who died two years ago, and Sheetal, a frail 7-month-old girl who died just a few months ago. But everyone in the slum drinks the water, usually without boiling, and water seems so natural and nurturing that Mrs. Bhagwani does not understand the menace it contains.”

January 8, 1817: Tsunami on the Delaware Estuary; 1957: Death of C.E.A. Winslow

A model predicted the tsunami wave height from a Jan. 8, 1817, earthquake offshore South Carolina. The earthquake’s magnitude was estimated at 7.4 from newspaper accounts.

January 8, 1817:  Tsunami on the Delaware Estuary.  New geological modeling has suggested that a magnitude 7.4 earthquake occurred off of South Carolina in 1817. The resulting tsunami tossed boats around on the Delaware Estuary south of Philadelphia according to newspaper reports at the time.

“The size and location, or epicenter, of the 1817 earthquake has never been pinned down so closely before. U.S. Geological Survey research geophysicist Susan Hough and her colleagues zeroed in on the source from newly uncovered archival records, looking at where the shaking was strongest. But they weren’t sure about the tsunami link: The 11 a.m. arrival time seemed too late for a 4:30 a.m. earthquake. So they created a computer model of the tsunami, testing different locations and magnitudes. The best fit to force a foot-high (30 centimeters) wave up the mouth of Delaware Bay by about 11 a.m. was a magnitude-7.4 earthquake offshore of South Carolina.

‘That was the eureka moment,’ Hough told Live Science’s Our Amazing Planet. ‘Darned if that wave doesn’t hit the Delaware River and slow way down.’

The foot-high tsunami wave started about 800 miles (1,300 kilometers) south of Delaware Bay and 400 to 500 miles (650 to 800 km) offshore of South Carolina, according to the study, published in the September/October issue of the journal Seismological Research Letters….

No obvious culprit jumps out of the seafloor topography, such as a linear feature that could be an earthquake-causing fault, Hough said. But according to ship records, the sea above the temblor’s likely epicenter trembled for several years. Earthquakes can be felt at sea, and ship captains reported shaking before and after Jan. 8, 1817, that could have been foreshocks and aftershocks, the researchers said. Ships in the area also rocked or shook from earthquakes in 1858, 1877 and 1879.”

January 8, 1957:  Death of Charles-Edward A. Winslow.“Charles-Edward Amory Winslow (4 February 1877 – 8 January 1957) was an American bacteriologist and public health expert who was, according to the Encyclopedia of Public Health, “a seminal figure in public health, not only in his own country, the United States, but in the wider Western world.”

Winslow was born in Boston, Massachusetts and attended Massachusetts Institute of Technology (M.I.T.), obtaining a B.S. in 1898 and an M.S. in 1910.

He began his career as a bacteriologist. He met Anne Fuller Rogers when they were students in William T. Sedgwick’s laboratory at M.I.T., and married her in 1907. He taught at the Massachusetts Institute of Technology while heading the sewage experiment station from 1908 to 1910, then taught at the College of the City of New York from 1910 to 1914.

He was the youngest charter member of the Society of American Bacteriologists when that organization was founded in 1899. With Samuel Cate Prescott he published the first American textbook on the elements of water bacteriology.

In 1915 he founded the Yale Department of Public Health within the Yale Medical School, and he was professor and chairman of the Department until he retired in 1945. (The Department became the Yale School of Public Health after accreditation was introduced in 1947.) During a time dominated by discoveries in bacteriology, he emphasized a broader perspective on causation, adopting a more holistic perspective. The department under his direction was a catalyst for health reform in Connecticut. He was the first director of Yale’s J.B. Pierce Laboratory, serving from 1932 to 1957. Winslow was also instrumental in founding the Yale School of Nursing.

He was the first Editor-in-Chief of the Journal of Bacteriology, serving in that position from 1916 to 1944. He was also editor of the American Journal of Public Healthfrom 1944 to 1954. He was curator of public health at the American Museum of Natural History from 1910 to 1922. In 1926 he became president of the American Public Health Association, and in the 1950s was a consultant to the World Health Organization.”

January 6, 1875: Birth of Harriette Chick

January 6, 1875:  Birth of Harriette Chick.“Dr. Dame Harriette Chick, DBE (6 January 1875 – 9 July 1977) was a notable British protein scientist and nutritionist. She developed the first relationship showing bacterial kill as a function of disinfectant concentration and contact time. Educated at Notting Hill & Ealing High School, She served as secretary of the League of Nations health section committee on the physiological bases of nutrition from 1934 to 1937. In 1941 she was a founding member of the Nutrition Society, of which she served as president from 1956 to 1959.

Chick and Charles James Martin discovered that the process of protein denaturation was distinct from protein coagulation (or flocculation), beginning the modern understanding of protein folding. She is known for having formulated Chick’s Law in 1908, giving the relationship between the kill efficiency of organisms and contact time with a disinfectant. Chick’s Law was later modified by Dr. H.E. Watson in 1908 to include the coefficient of specific lethality. The Chick-Watson Equation is still used today.

In 1915, she went to the Lister Institute in Elstree to test and bottle tetanus antitoxin for the army. Together with Dr. Elsie Dalyell, she led a team from the Lister Institute and the Medical Research Institute in 1922 to study the relation of nutrition to bone disease. They discovered the nutritional factor causing rickets, and proved that fat-soluble vitamins present in cod liver oil, or exposure to ultra violet light, could cure and prevent rickets in children. She worked at the Lister Institute for over fifty years, and isolated vitamin C in various other fruits and vegetables.”

Chick’s Law-Basis of Disinfectant validation and D value. “In 1908 a British scientist, Dr. Harriet Chick, described a method for estimating the destruction of microorganisms by chemical disinfectants (Chick 1908). She postulated that the microbial mortality would follow what in physical chemistry would be called ‘first-order kinetics’—that is, mortality vs time data plots as a straight line on a semi-logarithmic graph. In practice, her postulate was correct and the law works for all liquid disinfectants and for many sterilization processes (for example, Chick’s Law has evolved into what is now referred to as D-value in autoclave sterilization).

This simple ‘Law’ (actually an equation) was modified quickly to account for varying disinfectant concentrations, and the pH of the disinfectant solution and the modified equation is now commonly called the ‘Chick-Watson Law.’”

Reference:  Chick, Harriette. (1908). “An Investigation of the Laws of Disinfection.” The Journal of Hygiene. 8:1 92-158.