[Report of the Medical Officer of Health for Enfield] page 167

Enfield 1967

[Report of the Medical Officer of Health for Enfield]

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TABLE 32 WATER SUPPLYMetropolitan Water Board Average Bacteriological Results

	Results before Treatment
	*Thames Derived North of River	New River Derived	Copper-mills Works	Hoe Lane Well Derived	Hadley Road Well Derived	Waltham Abbev Well Derived
	Number of Samples	—	—	—	170	246	250
	Agar Plate Count per ml. 20-24 hrs. at 37°C	-	-	-	0.2	10.5	0.1
	3 days at 22°C	—	—	—	5	46	8
Coliform Count Percentage of samples in neg. 100 ml	-	-	-	98.82	80.89	100
Count per 100 ml.	—	—	—	-	10	—
Escherichia coli Count Percentage of samples in neg. 100 ml	-	-	-	98.82	84.55	100
Count per 100 ml	-	—	—	—	9.5	—
	Results after Treatment
Number of Samples	1,691	510	48	172	251	255
Agar Plate Count per ml. 20-24 hrs. at 37° C	16.0	6.7	92.4	0.0	4.5	0.0
3 days at 22°C	—	—	—	1	88	13
Coliform Count Percentage of samples in neg. 100 ml	100	99.61	100	100	100	99.61
Escherichia coli Count Percentage of samples in neg. 100 ml	100	99.8	100	100	100	100

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* Ashford Common, Kempton Park, Hanworth Road and Barn Elms

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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		0.00
Colour (Burgess)	Less than 5		Albuminoid Nitrogen		0.00
Odour/Taste	Nil/Nil		Nitrate Nitrogen		6.0
Turbidity	0		Nitrite Nitrogen		0.00
Conductivity	570		Oxygen Absorbed		0.00
Total Solids	385		Fluoride		less than 0.2
pH	7.0		Silica		19
Free CO₂	22		Iron		less than 0.02
Alkalinity (CaCO₃)	245		Other Metals :
Carbonate Hardness	245		Copper/Zinc/Lead		Absent
Non-Carbonate Hardness	60		Phosphate		0.12
Total Hardness	305		Residual Chlorine		Nil
			Temperature (°C)		16
Bacteriological Examination
		1 day at 37° C		2 days at 37° C	3 days at 20° C
No. of Colonies developing on Agar		0 per ml.		2 per ml.	0 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.
C1. Welchii		— ml.		— ml.