[Report of the Medical Officer of Health for Enfield] page 168

Enfield 1968

[Report of the Medical Officer of Health for Enfield]

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TABLE 32

WATER SUPPLY Metropolitan Water Board Average Bacteriological Results

	Results before Treatment
	Thames Derived North of River	New River Derived	Hoe Lane Well Derived	Hadley Road Well Derived	Waltham Abbey Well Derived
Number of Samples	_	_	194	247	245
Agar Plate Count per ml. 20-24 hrs. at 37 °C		_	6.3	0.4	0.1
3 days at 22 °C	—	—	16	44	6
Coliform Count Percentage of samples in neg. 100 ml	_-	_	99.48	85.43	99.59
Count per 100 ml Escherichia coli Count	—	—	-	0.6	-
Percentage of samples in neg. 100 ml	—	—	99.48	88.26	100.0
Count per 100 ml	—	—	—	0.3	—
Count per 100 ml	Results after Treatment
Number of Samples Agar Plate Count per ml.	1,720	514	199	252	252
20-24 hours at 37°C.	12.1	11.9	0.1	2.0	0.0
3 days at 22°C Coliform Count	—	—	24	19	16
Percentage of samples in neg. 100ml Escherichia coli Count	99.94	100.0	100.0	100.0	100.0
Percentageofsamplesinneg. 100ml	99.94	100.0	100.0	100.0	100.0

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TABLE 33

WATER SUPPLY Lee Valley Water Company Representative Sample

Chemical Results Expressed in Milligrams per Litre
Appearance	Clear and Bright		Ammoniacal Nitrogen 0.01
Colour (Burgess)	Less than 5		Albuminoid Nitrogen 0.01
Odour/Taste	Nil/Nil		Nitrate Nitrogen 7.0
Turbidity	0		Nitrite Nitrogen 0.00
Conductivity	590		Oxygen Absorbed 0.02
Total Solids	405		Fluoride less than 0.2
PH	7.2		Silica 12
Free CO2	31		Iron less than 0.02
Alkalinity (CaCO2)	220		Other Metals: Copper/Zinc/Lead Absent
Carbonate Hardness	220		Phosphate 0.16
Non-Carbonate Hardness .	90		Residual Chlorine Nil
Total Hardness	310		Temperature (°C.) 2
Bacteriological Examination
No. of Colonies developing on Agar		1 day at 37°C. 0 per ml.		2 days at 37°C. 1 per ml.	3 days at 20°C. 5 per ml.
		Present in		Absent from	Probable No.
Presumptive Coli-Aerogenes		— ml.		100 ml.	0 per 100 ml.
E. Coli		— ml.		100 ml.	0 per 100 ml.
CI. Welchii		— ml.		— ml.