[Report of the Medical Officer of Health for Chislehurst] page 47

Chislehurst 1957

[Report of the Medical Officer of Health for Chislehurst]

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Description of the Sample	Bexley Well	Orpington Well	North Orping-Well	Short-lands No. 1	Short-lands No. 2	Eyns-ford Well	Eyns-ford Bore	Horton Kirby	Wilmington No. 1	Wilmington No. 2	Darenth Well	Darenth Bore Hole	Thames derived
Before Chlorination (Raw Water)
No. of Samples Plate Counts (Average per ml.]	321	251	215	161	92	231	121	241	236	225	239	209	—
Colonies counted on Agar: 37° C. (20-24 hours)	0.2	0.04	1.2	0.04	0.1	0.03	0.02	0.1	0.8	0.1	0.2	1.6	-
22° C. (3 days)	4.3	102.0	53.4	4.9	2.2	15.0	81.0	27.7	57.4	14.5	7.5	14.8	—
Coliform test. Percentage samples negative in 100 ml.: Coliform	99.10	94.82	3.26	100.0	100.0	97.40	99.17	96.27	88.98	88.80	94.98	95.69	-
E. Coliform	100.0	99.60	26.51	100.0	100.0	99.57	99.17	98.76	99.58	99.56	100.0	99.04	—
After Chlorination (Water passing into Supply)
Number of Samples	252	256	221	256	256	234	124	246	255	255	255	255	3438
Plate Counts (Average per ml.) Colonies counted on Agar: 37°C. (20-24 hrs.)	0.02	0.03	0.7	0.2	0.2	0.02	0.04	0.2	0.1	0.1	0.4	0.4	6.4
22°C. (3 days)	4.3	16.0	21.2	3.6	3.6	11.3	1.2	27.0	2.8	2.8	5.4	5.4	—
Coliform test Percentage samples negative in 100 ml.: Coliform	100.0	100.0	99.10	100.0	100.0	97.44	100.0	99.59	98.82	98.82	100.0	100.0	99.33
E. Coliform	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	99.91