Bacteriological Study oe Denver Water Supply 9 
BACTERIOLOGICAL EXAMINATION OF DENVER CITY 
WATER SUPPLIED BY THE DENVER UNION 
WATER COMPANY—COMPARATIVE RESULTS 
FROM FOUR LABORATORIES. 
At the request of Mr. D. G. Thomas, Chief Engineer of the 
Denver Union Water Company, a comparative study of the raw 
and treated waters furnished by the Company was undertaken 
November 11, 1916, by four different laboratories working sep¬ 
arately and independently. Those co-operating in this investiga¬ 
tion were Dr. Wm. C. Mitchell, Bacteriologist for the City and 
County of Denver, Denver, Colorado, Dr. John B. Ekeley, State 
Chemist, University of Colorado, Boulder, Colorado, Dr. H. I. 
de Berard, Chemist, Denver Union Water Company, Denver, 
Colorado, and Professor W. G. Sackett, Bacteriologist, Colorado 
Experiment Station, Fort Collins, Colorado. 
On November 11th, representatives from the four above labora¬ 
tories met in Denver and were taken by automobile on an inspec¬ 
tion trip over practically the entire system. Each had his own 
sterilized sample bottles and took samples according to his own 
particular practice from twelve different points over the system. 
These included the following:— 
1. Mississippi Avenue, infiltration galleries, inlet West Den¬ 
ver reservoir; treated. 
2. Platte River, intake to Marston Lake, 48-inch conduit; 
raw. 
3. Bear Creek; intake to Marston Lake, flume; raw. 
4. Marston Lake; outlet to North Side Marston Lake plant; 
raw. 
5. North Side Marston Lake plant; treated. 
6. Platte Canon infiltration galleries, 30-inch conduit, 
Wynetka; treated. 
7. vSlow sand filters, 40-inch conduit, Wynetka; treated. 
8. Willard rapid filters, 34-inch conduit, Wynetka; treated. 
9. South Side Marston Lake plant, 48-inch conduit, 
Wynetka; treated. 
10. Drinking fountain, City, First and Broadway. 
11. Cherry Creek infiltration galleries, Capitol Hill reser¬ 
voir ; not treated. 
12. Tap in City chemical laboratory. 
All samples were iced immediately upon collection and kept 
in this condition during transit and until arrival at destination. 
