luring the day and a reduced speed during the night thus testing too 
everely the working of the filters. The impounding reservoirs in protracted 
Iry weather get too low and any heavy shower in any part of the catchment 
irea may result in stirring up the whole body of water in the reservoir and 
lulifying the effect of the previous sedimentation. 
)'■ 
The Acting State Engineer, Mr. W. E. Kenny, and the Executive 
engineer of the Water Works, Mr. J. E. Bach, have kindly supplied me with 
particulars of the water supply for Kwala Lumpur from which the following 
igures are taken — 
Catchment Area, 500 acres, an additional 1,000 acres has recently 
been included. 
Capacity of Impounding Reservoir, maximum 37,710,000 gallons. 
Capacity of Service Reservoir, 1,740,000 gallons. 
Supply daily to Kwala Lumpur, 540,000 to 450,000 gallons. 
Average consumption per head per diem 12^- gallons. 
The water from the reservoir taken about 2 feet from the surface is 
lelivered to each filter by a bell-mouthed inlet 2 feet in diameter about 
[ ft. 6 in. above the level of the sand. The filter bed is 60 feet below T the 
evel of the reservoir and heavy stones are placed round the inlet and above 
he sand to break the force of the water. 
The filter beds are 127 feet by 66 feet at the level of the sand and 7 feet 
ieep from floor to coping. 
The filtering material consists from below upwards of: — 
(1) A layer of bricks on edge in rows 4^ inches apart resting on 
the concrete floor. 
(2) A layer of bricks laid flat about ^ inch apart. 
(3) A layer of broken stone 12 in. deep. The stone at the bottom 
is broken to gauges of 2\ inches and at the top about i-§- inches. 
(4) A layer of coarse clean quartz sand 2 feet deep with about 
4 inches at the top of rather finer sand. 
In long continued dry weather when the flow of water into the reservoir 
was steady and moderate the effect of subsidence was marked. On two 
such occasions only 51 and 66 organisms were found per cc. and in the 
nlet to the filter bed only 24 and 51 respectively. After heavy rain, 2 in. 
bn 12 hours, the whole water in the reservoir was stirred up and muddy and 
.is many as 8,800 organisms were present per cc. These w r ere the two 
I extremes on two other occasions 120 and 150 organisms were present but 
300, 400 or 500 with intermittent dry and wet weather when the supply to 
* :he reservoir was in excess of the discharge from it were the common 
1 'esults obtained. Four days after the highest number though the rain had 
I )een moderate the number of organisms found was still 1,655 P er cc - 
It is clear therefore that under the climatic conditions present in Malaya 
small or medium sized reservoirs cannot be relied on to purify the water by 
subsidence and that the results of storage in such a reservoir will be inter¬ 
nment as in dry weather water purer than the intake will be obtained but 
m rainy weather water of worse quality will be discharged than that which 
enters it. 
