PAPERS ON WATER SUPPLY 87 



In April, 1911, the attention of the Illinois State Water 

 Survey was called to a serious incrustation which had formed 

 in the city water mains at Mt. Vernon, Illinois.* As a conse- 

 quence, the pressure had become greatly reduced, and in some 

 places complete stoppage of service pipes had occurred. An 

 examination showed that the incrustation contained a large 

 amount of manganese dioxide. The original water contained 

 0.7 parts per million of manganese. Later, water supplies in 

 other cities were found to contain manganese. Consequently 

 it seemed advisable to examine samples of water from sources 

 which would be representative of typical supplies in order to 

 obtain further information on this subject. 



The results thus far obtained from the examination of the 

 water supplies of the state are shown in the table. The 

 amounts of manganese, iron, and residue on evaporation at 

 180°C are given, with the locality, the depth of well and the 

 geological stratum penetrated. The words, St. Peter and 

 Potsdam, refer to the series of sandstones known under these 

 names. The samples were in all cases taken at the original 

 sources, and not from the city taps. 



One hundred and twenty-three waters from one hundred 

 and three different cities were examined. The results show 

 that the supplies of fifteen of these cities contain more than 

 0.1 parts per million of manganese, the average of the fifteen 

 being about 0.4 parts per million. It is apparent therefore, 

 that manganese is not unusual in the water supplies of Illinois. 



No manganese was found in ten of the waters from the 

 thirteen wells which penetrate the Potsdam sandstone. The re- 

 maining three contained very small amounts, 0.8 parts per 

 million in a well at Elgin, .04 at Riverside, and .04 at Utica. 

 No manganese was found in twenty-three of the waters from 

 twenty-five wells which reach the St. Peter sandstone. The 

 other two contained small amounts, .10 parts per million in 

 water from a well at Elgin, and .03 parts in a well at River 

 Forest. The two wells at Elgin which show the high man- 

 ganese content are cased to a depth of less than 100 feet, and 

 may be drawing water from upper strata. Manganese, then is 

 not usually found in waters from deep wells in the sandstones. 



Ten of twelve samples examined from wells in alluvial drift 

 contained manganese. The average content of the ten was .52 

 parts per million. Manganese is, then, very frequently present 

 in wells in alluvial drift. 



•Univ. of 111. Bull., Waterway Survey Series No. 10, 52-57, 57-65. Proc. 111. Water 

 Supply Assn. 1912, 202-8, 209-12. 



