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SANITARY CIRCUMSTANCES OF THE AREA
Water
The Metropolitan Water Board is the supplying authority.
The supply to the Crayford district is a mixture of water from Crayford,
Dartford, Darenth, Wansunt and Wilmington wells. All the water is chlorinated
on the works, but any excess remaining after a period of contact is removed
completely before the water is passed into supply.
Bacteriological analyses are carried out at least five times per week for
all supplies both before and after chlorination.
All new and repaired mains are chlorinated before being restored to use
and samples of water from them are tested to see that the quality conforms
with that normally supplied before the main is passed for service.
None of the supplies is plumbo¬solvent.
The water from Crayford well station of the Metropolitan Water Board is
normally very pure, even before treatment, but for the second time in recent
years, this source suffered more or less serious contamination in the course
of the year. This happened previously in 1950 when Number 3 well was seriously
polluted by the overflow from a blocked sewer. On this second occasion inspection
of the routine bacteriological culture tubes in the Water Examination
Department of the Metropolitan Water Board for the sample taken on 2nd October,
showed that Number 2 well had an Escherichia coli count of 16 and Number 3 had
a coliform count of 2 per 100 ml. These waters are normally completely free of
both organisms and their presence indicated that something was amiss. The tests
showed that the water passing into supply after treatment was of the normal
high standard but it was obviously necessary to watch the situation closely.
Samples on the two successive days showed a further deterioration in the condition
of the raw water and, although the water passing into supply was still
unaffected, it was decided to close the station down as a precautionary measure.
Inspection of the drains on the station did not reveal the source of the
contamination and it was arranged that the Board's Drainage Inspector should
co-operate with the Council's Public Health Inspector in investigating the
sewers in the vicinity of the pumping station. It was ascertained that a sewer
behind some shops on the other side of the road from the pumping station had
been blocked and had overflowed into a nearby soakaway. The blockage was
cleared on Monday 5th October.
Number 2 well, which was the one most seriously affected, was pumped to
waste in an endeavour to get rid of the pollution. Number 3 well gave no
further evidence of contamination and was returned to supply. The bacteriological
quality of Number 2 well slowly improved and it was returned to service
on 5th November.
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