258 
TYPHOID FEVER IN DISTRICT OF COLUMBIA. 
In January, 1902, a third reservoir and sediment basin, known as 
the Washington City reservoir, having a capacity of about 300,- 
000,000 gallons, was put into service. From 1902 to October, 1905, 
the city was supplied with water partly from the Washington City 
reservoir and partly from the Georgetown reservoir, in about the fol- 
lowing proportions : 
Date. 
Average quantity, in mil- 
lion gallons, daily flow- 
ing to city from — 
Percentage of total supply 
flowing to city from— 
Georgetown. 
Washington 
City. 
Georgetown. 
W ashington 
City. 
1902 
40 
19 
68 
32 
1903 
39 
22 
64 
36 
1904 
34 
32 
52 
48 
1905, first half 
29 
37 
44 
56 
Since October, 1905 
0 
69 
0 
100 
Note. — T hese figures were furnished by Mr. F. F. Longley, chief chemist of the Washington filtra- 
tion plant, and were computed from Aqueduct records of elevations in the two reservoirs, and probably 
are a good indication of relative quantities flowing from the two reservoirs. 
The filtration plant was put into complete operation in October, 
1905, since which time all the water delivered to the city has been 
filtered after sedimentation in the three storage basins, viz, Dalecarlia, 
Georgetown, and Washington City reservoirs. 
To recapitulate: From 1859 to 1863 Washington received its water 
supply from Little Falls Branch, collected in Dalecarlia reservoir and 
stored and distributed from the Georgetown reservoir. 
From 1863 to 1888 the supply was derived partly from Little Falls 
Branch and Dalecarlia reservoir and partly from the Potomac River 
taken at Great Falls. From these two sources the water was collected 
in and distributed from the Georgetown reservoir. 
From 1888 to 1895 the Little Falls Branch and Dalecarlia reservoir 
were not used, and the city received only Potomac River water 
tlnrough the conduit direct to Georgetown distributing reservoir. 
From 1896 to January, 1902, the Dalecarlia reservoir, from which 
Little Falls Branch was now excluded, was again used and the city 
was given Potomac River water, received in Dalecarlia reservoir and 
then passed into Georgetown reservoir from which it was distributed. 
From January, 1902, to October, 1905, an additional sediment and 
distributing basin, viz, the Washington City reservoir, was added to 
this service. 
Since October, 1905, the Potomac River water passes through the 
three subsiding basins, viz, Dalecarlia, Georgetown, and Washington 
reservoirs, and then through the sand filters. It should be remem- 
bered, however, that the Dalecarlia reservoir is sometimes by-passed. 
