[Report of the Medical Officer of Health for Chislehurst] page 27

Chislehurst 1953

[Report of the Medical Officer of Health for Chislehurst]

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Table: BACTERIOLOGICAL RESULTS

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BACTERIOLOGICAL RESULTS

	Orpington Well	N. Orpington Well	Shortlands Well	Eynsford Well	Bexley Well	Wilmington Well	Darenth Well	Thames derived filtered water
Before Chlorination (Raw Water)
Number of samples	249	242	493	265	581	402	131	7930
Plate Count (Average per millilitre) Colonies counted on Agar:
22°C. (3 days)	1825.6	33.2	1.9	162.6	0.7	381	1.8	Nil
37°C. (20-24 hours)	34.4	1.7	0.1	0.7	0.2	0.8	0.6	Nil
Bact. coli test:
Percentage samples negative in 100 ml.	99.6	33.1	99.8	99.6	100.0	99.0	99.2	Nil
Average number per 100 ml	0.008	18.000	0.004	0.008	Nil	0.015	0.015	Nil
After Chlorination (Water passing into Supply)
Number of samples	255	248	253	272	309	251	253	Nil
Plate Count (Average per millilitre) Colonies counted on Agar:
22°C. (3 days)	Nil	Nil	Nil	Nil	Nil	Nil	Nil	Nil
37°C. (20-24 hours)	Nil	Nil	Nil	Nil	Nil	Nil	Nil	Nil
Bact. coli test:
Percentage samples negative in 100 ml.	100.0	100.0	100.0	99.6	100.0	100.0	100.0	99.9
Average number per 100 ml	Nil	Nil	Nil	0.009	Nil	Nil	Nil	0.001