158
REPORT.
The sample of the canal water shows a very large amount of pollution, fœcal bacilli being present in • 01 cc. The,
organisms present however show that a certain amount of settlement and purification has taken place.
2. The samples taken from the two settling tanks show fœcal bacilli in 5 cc. This improvement, which '
much, is due to the action of sun-light and storage.
3. The filtered water shows absolutely no improvement whatever on that of the settling tanks. Fœcal bacilli a
present in 5 cc.
4. Two samples from the distributary system show that the action of the pipes has further improved the quality
the water, final bacilli being present in 20 and 50 cc.
5. The sample taken from one of the four taps in front of the Collector's office shows as on former occasion,
that the water from this point is very much worse than all other samples. In this instance fœcal bacilli are present
in cc. The total colonies are reported as countless. The explanation for this state of affairs is probably that somewhere
on this pipe line there is a leak in the pipes . The whole of this line should be very carefully inspected by the water
works overseer and any leak remedied.
Chemically the filtered water is very nearly up to the standard of a good water.
The water in the town is better than previous quarters owing to the more intelligent use of the settling tanks
Recommendation.—The
greatest possible care should be taken in working the settling tanks as directed in the
inspection report, in order to get the maximum period of storage in the tanks, before the water is sent into the town.
Inspection Report.
I inspected the water-works on 5th February 1909. On the whole they are satisfactory with the exception
the filter beds. There is however one other point on which I wish to make a few remarks, viz., the method of workit
the storage or settling tank. It has been proved in recent years that storage of water is one of the most satisfact
methods of purifying it Furtber the work carried out at the King Institute shows that the removal of objectional
bacilli is extremely rapid with proper exposure to the action of sun-light. Consequently the storage tanks should be
used as to give the maximum numbers of days' exposure to sun, without the addition of fresh canal waters. Both tan
should be kept always as full as possible, waters being taken from one only, when this reservoir has run as low as it
advisable, which will probably take from 7 to 9 days, the other reservoir should be taken into use, and pumping shou
go on as rapidly as possible to fill up the empty tank. By this means it should be possible to ensure at least 5 or 6 date
exposure to sun-light without the admission of unstored water. An example of the difference betw en a stored a
unstored water, is to be found in the two samples already taken—the one in August shows fœcal bacilli in 1 cc. a
those present being harmless ; in the sample taken in December fœcal bacilli were present in 1 cc. and the organis,
were distinctly more objectionable. Consequently every endeavour should be made to give the maximum amount
undisturbed storage that the capacity of the tanks will allow.
The great fault that is to be found with the filters, is, that the sand used is much too coarse for the prof
purification of waters. This results in very great variation in the quality of the filtered water. The probable conditi
of affairs is something as follows :--On the opening pening of the canals, after the two months' closure, a very bad quality
flood water is admitted to the storage tank. These both being very low, on account of the excessive demand at this
of the year, adequate storage is impossible. The consequence is that the whole of the sand of the filter beds become
thoroughly impregnated with fœcal bacilli, on account of the had quality of the water used at this time. As time g
on the water in the canal becomes purer, adequate storage is carried out, so that the water sent on to the filter bed:
fairly good, but for some months after the opening of the canals the sand in the filter beds continues to add organis
to the water, so that the filtered water is inferior to the unfiltered. This is. exactly what was taking place when
first sample (August 31st) was analysed. As time goes on the bacilli in the sand become fewer, so that the filters thou
not improving the water very markedly, do not add additional organisms to it. This is the state of affairs that
reached in December last I recommend that as no fine sand is to be obtained locally, experiments be conducted to ascert
what proportion of fine sand it is possible to sieve out of the Hindri sand, and what will be the cost per 100 cubic feet
this seived sand ; when this figure has been obtained it will be possible to estimate the cost of replacing the useless c
s a n d b y f i n e r m a t e r i a l .