London's Pulse: Medical Officer of Health reports 1848-1972
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Hints from the Health Department. Leaflet from the archive of the Society of Medical Officers of Health. Credit: Wellcome Collection, London
Harrow 1965
[Report of the Medical Officer of Health for Harrow]
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85
ENVIRONMENTAL HEALTH SERVICE
WATER SUPPLY
Apart from a small area in the extreme south-west part of the district
which is supplied by the Rickmansworth and Uxbridge Valley Water
Company, the Borough is supplied by the Colne Valley Water Company.
Nearly all the water supplied by them is obtained from a series of wells
fed from gathering grounds in the Chilterns.
The supply has been satisfactory in quantity and quality and no adverse
reports were received.
During the year 1,085 samples of raw water were submitted by the
Colne Valley Water Company for examination and of 2,623 samples of
supply water examined by the Company, 100 were from points within the
Borough. The results were satisfactory.
In addition to these samples, twenty-four were taken by the Department
from dwellings in various parts of the district and the following is a
copy of the chemical analysis of a sample submitted for examination during
December:—
Chemical Results in parts per million
| Suspended matter | absent |
| Appearance | clear |
| Colour | less than 5 hazen units |
| Taste | normal |
| Odour | absent |
| Total Solid Residue dried at 99°C. | 396 parts per million |
| Chlorides as Chlorine | 55 ,, ,, ,, |
| Nitrate Nitrogen | 3 ,, ,, ,, |
| Nitrite Nitrogen | absent |
| Ammoniacal Nitrogen | 0.22 „ „ „ |
| Albuminoid Nitrogen | 0.08 „ „ „ |
| Oxygen absorbed, 4 hrs. at 27°C. | 0.30 „ „ „ |
| Total Hardness as CaC03 | 210 „ „ „ |
| Non-carbonate Hardness as CaCO3 | 85 |
| Alkalinity as CaCO3 | 125 |
| Poisonous Metals | absent |
| Reaction (pH) | 7.4 |
"This is a moderately hard water with a low total solids and is chemically
suitable for use as a domestic supply."
The Colne Valley Water Company advise that the fluoride content of
water supplied by them to the area served by the London Borough of
Harrow is consistently less than 0.1 p.p.m. (F).