[Report of the Medical Officer of Health for Chigwell] page 22

Chigwell 1966

[Report of the Medical Officer of Health for Chigwell]

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	Chingford Mill	Ferrv Lane	Lee Bridge	Waltham Abbey
Sodium as Na	-	-	35.0	-
Potassium as K	-	-	7.1	-
Chloride as Cl	31	38	43	25
Phosphate as Po₄	-	-	2.9	-
Silicate as Sio₂	14	16	6	19
Sulphate as So₄	110	182	109	85
Natural Fluoride as F	-	-	0.20	-
Surface-active material as Manoxol OT	-	—	0.04	—
Turbidity units	0.2	0.3	0.4	0.8
Colour (Burgess units)	9	4	18	7
pH value	7.7	7.5	8.1	7.4
Electrical Conductivity (micromhos)	590	750	690	570
(b) Results of Bacteriological Examination:
BEFORE TREATMENT -
No. of samples	121	-	-	249
Agar plate count per ml.:-
20-24 hours at 37°C	0.5	-	-	0.1
3 days at 22°C	14	-	-	4
Coliform count:-
Per cent samples negative in 100 ml.	99.17	—	—	100.0
Escherichia coli count:-
Per cent samples negative in 100 ml	100.0	-	-	100.0
AFTER TREATMENT -
No. of samples	123	185	513	253
Agar plate count per ml.:-
20-24 hours at 37°C	0.4	11.8	32.3	0.7
3 days at 22°C	35	-	-	5
Coliform count:-
Per cent samples negative in 100 ml.	100.0	99.46	98.25	100.0
E.coli count:-
Per cent samples negative in 100 ml	100.0	100.0	100.0	100.0

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