[Report of the Medical Officer of Health for Enfield] page 159

Enfield 1969

[Report of the Medical Officer of Health for Enfield]

This page requires JavaScript

Download table as:

TABLE 30 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	Wallham Abbey Well Derived
	Number of Samples	8,196	1,502	249	239	249
	Agar Plate Count per ml. 20-24 hrs. at 37 °C.	66.5	77.6	0.2	0.2	0.1
	3 days at 22°C.	—	—	16	34	9
Coliform Count
Percentage of samples neg. in 100 ml.	39.79	45.27	99.20	89.12	99.60
Count per 100 ml.	19.0	10.0	—	0.5	—
Escherichia coli Count
Percentage of samples neg. in 100 ml.	53.97	61.78	99.60	90.38	100.0
Count per 100 ml.	70	2.7	—	0.3	—
	Results after Treatment
Number of Samples	3,698	514	229	248	253
Agar Plate Count per ml. 20-24 hrs. at 37 °C.	12 .9	13.1	0.5	0.2	0.2
3 days at 22°C.	—	—	6	16	6
Coliform Count
Percentage of samples neg. in 100 ml.	99.89	100.0	100.0	100.0	99.60
Escherichia coli Count
Percentage of samples neg. in 100 ml.	100.0	100.0	100.0	100.0	100.0

Download table as:

TABLE 31 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		4.7
Turbidity	0		Nitrite Nitrogen		0.00
Conductivity	590		Oxygen Absorbed		0.00
Total Solids	425		Fluoride		less than 0.2
pH	7.1		Silica		12
Free CO2	27		Iron		less than 0.02
Alkalinity (CaCO3)	230		Other Metals:
			Copper / Zinc / Lead		Absent
Carbonate Hardness	230		Phosphate		0.08
Non-Carbonate Hardness	100		Residual Chlorine		Nil
Total Hardness	330		Temperature (°C.)		13
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.		0 per ml.		3 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.