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There were four reports of contaminated hydrant supply during the year. Two contaminated
hydrants were discovered during the course of routine sampling and fortunately they were not used
to supply ships with drinking water. Of the others, one hydrant involved a ship which had been
supplied with "suspicious" water and had sailed prior to the result of the analysis. The vessel was
contacted at sea by W/T and advised to chlorinate all fresh water on board. In the case of the
fourth hydrant supplying unsatisfactory water the cause was attributed to the extraordinary tidal
flooding of the docks on the afternoon of the 10th December.
In the dock areas, eight "suspicious" and one "unsatisfactory" samples from the ends of
delivery hoses and one "suspicious" sample from a stand pipe, were reported by the laboratories.
The reasons for these reports were fully investigated and standard sterilising measures were
adopted in each case. No specific causes for these incidents were discovered and negligent
handling of equipment must, therefore, be assumed.
During the very high tides in December some flooding of the sunken hydrant pits occured
with consequent contamination of the fittings. This problem had been anticipated and supplies
to ships from the affected hydrants were stopped. When the floods subsided all hydrants affected
were subjected to super-chlorination under the supervision of the Port Health Inspector concerned
and a quantity of fresh water run to clear hydrants before supplies were resumed. The pit linings
were treated with a strong solution with chloride of lime as an extra precaution. Samples of water
were taken and sent for bacteriological examination and all results indicated the absence of
coliform organisms and a very low plate count.
There was some flooding of spaces in which food stuffs were stored and any foodstuffs contaminated
were detained for appropriate action.
During the year there were three instances of "suspicious" or "unfit" fresh water supplies
to galley and messroom sinks from fore and after peak bulk storage tanks. In one instance, the
after peak tank, which had been normally used for salt water ballast, was brought into service
while in a foreign port without prior cleaning to act as a supplementary fresh water tank during
an extended voyage.
The accidental or improper use of the engine room service pump was the cause of contamination
of the fresh water distribution on three ships. After detailed investigations of all other incidents,
no positive clues to cause of contamination were discovered.
The cleansing, cement washing and chlorination of the contaminated tanks, the flushing of
the distribution systems and re-sampling was carried out in all cases before shipboard supplies
were resumed.
Fresh water supplied to sinks and wash basins is frequently consumed by crews as palatable
water. It is essential, therefore, that all fresh water on board ship should be free from contamination
and should be as clean as possible and attain the standard applicable to drinking water.
During investigations into obscure causes of contamination and when no definite conclusions
are forthcoming, some consideration should be given to the cleanliness of the tank sounding rods
and the overall security of the sounding pipes. It is preferable that a particular sounding rod be
reserved for sounding drinking water tanks. It is therefore most essential that, not only the
routine sampling of Port fresh water supplies should be continued, but that ship storage and distribution
should also be sampled as a standard routine measure in the Port.
In view of the various incidental sources of contamination of water on board ships systematic
and regular sampling both at the supply hoses and ship distribution installations are essential.
3. Precautions taken against contamination of hydrants and hosepipes:—
There has been no major development to report during the year. The replacement of the old
pattern type of water meter boxes by single units incorporating stand pipe and meter has slowly
continued as required.
The following code of Practice has been faithfully applied by water operators and the figure
of 92.15 per cent of "satisfactory" "good" and "excellent" samples, although not as high as in
preceding years; gives rise to general Satisfaction:—
CODE OF PRACTICE
Equipment
All components should be kept clean and maintained exclusively for this purpose.
Equipment should be kept in a properly appointed store and transported to and from the watering
point in a suitable and covered truck.
No other equipment than that of the Port of London Authority should be used for supplying
fresh water.
All hoses should be lined with rubber internally.
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