has been issued to compel the town to purify its sewage.
Between Worcester and Tewkesbury very little sewage enters
the Severn. With the Worcester sewage diverted or puri-
fied, the Medical Officer and engineer consider that the
Severn water, properly collected and filtered, will afford an
abundant and perfectly wholesome supply to Cheltenham,
and more especially as the towns already deriving their
water supplies from the Severn are not unduly affected
by typhoid fever. The recent report of Dr. Barry on the
typhoid epidemic in the Tees valley has, however, caused
considerable alarm, and an agitation has been raised in the
town to protest against the works being proceeded with. A
promise, therefore, has been made that the river water shall
only be laid on for manufacturing and municipal purposes,
and not turned into the mains for general consumption
unless and until the present sources of supply absolutely fail.
This compromise will probably be accepted as satisfactory
by all parties.

Table VII. (Chapter X.) contains the analyses of several
typical samples of river water, including the filtered waters
supplied by the various London companies, during August
1892, derived from the rivers Thames and Lea.



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CHAPTER VIII

QUALITY OF DRINKING WATERS

Much has already been said about the suitability of waters
from various sources for domestic use, and fortunately it may
be taken as being generally true that the best water for drink-
ing purposes is also the best for cooking, washing, and other
domestic requirements, and also for probably all manufacturing
processes. A high degree of purity is not necessary in the
latter case ; hence a water which may be totally unfit for
drinking may still be of value for many other purposes ; but
as dual supplies introduce complications, and usually mean
additional expenditure, it is an undoubted advantage ft) have
a single supply equally well adapted for all uses. As health,
however, is of paramount importance, a pure water supply
is an absolute necessity for domestic use, and it is only where
the supply is limited, or the water is unfitted in some way
(as by being too hard), or is too expensive for manufacturing
purposes, that there will be any demand for an additional
supply. In many towns the requirements of manufacturers
are met by the laying of special mains conveying water from
a river, or some other source, yielding water too impure for
domestic use, yet perfectly well adapted for their special
requirements. Such water may also be utilised for flushing
sewer3, etc. On the sea-coast sea- water is sometimes used
for flushing sewers, etc., especially where it is cheaper to
pump it than use the domestic supply, or where the latter is
not too abundant.



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QUALITY OF DRINKING WATERS 105

The characteristics of a good potable water are freedom
from colour, odour, taste, turbidity, and excess of saline
matter and the total absence of all injurious substances,
whether of animal, vegetable, or mineral origin.

Colour. — A hygienically pure water is almost invariably
quite colourless when viewed in small bulk, as in a tumbler,
though when looked at in a reservoir, or in a tube about 2 feet
long, it will have a faint bluish tint.

Professor Tyndail showed that when a powerfully condensed



Fio. 12.— Tubea for comparing the colours of potable waters.

beam was caused to traverse a sample of water, the amount
of light scattered depended upon the quantity of impurity
present. But " an amount of impurity so infinitesimal as to
be scarcely expressible in numbers, and the individual par-
ticles of which are so small as wholly to elude the microscope,
may, when examined by the method alluded to, produce not
only sensible, but striking, effects upon the eye." Experi-
menting with sea-water, he found that a blue colour corre-
sponded with a high degree of purity. A yellow-green water
in the luminous beam appeared exceedingly thick with very
line particles, and a bright green water, though much more
pure than the yellow-green, was far more impure than the
blue. A green or yellow tint usually indicates the presence
of vegetable or animal matters ; a brown tint is almost invari-
ably due to peat ; whilst a reddish tint indicates the presence
of iron. Surface waters from hills and moorlands often con-
tain peaty matter in solution and are discoloured thereby, but
this discoloration forms only a sentimental objection to the



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106 WATER SUPPLIES

water, unless excessive, and the peat does not appear in any
way to affect the health of those who use it. Such waters
are usually very soft and well adapted for manufacturing
purposes generally, but there are some processes, as the
making of the finest qualities of paper, in which the use of
peaty water is objectionable. Some bleaching action takes
place when such water is freely exposed to sunlight and air,
as in lakes and large reservoirs. From observations made
in Massachusetts it was found that water " must be stored
several months to cause any material reduction in colour,
and from six months to a year in order to remove practically
all of it." A filter of sand and loam removed the whole of
the colour from the water of the Merrimac River for two
years. During the third year the filtered water was occasion-
ally coloured ; during the fourth and fifth year the effluent
from the filter "was very slightly but uniformly coloured."
New sand would therefore appear to be a more efficient
colour-remover than sand which has been in use as a filtering
material for a length of time.

Where the water has a reddish or reddish brown tint due
to the presence of iron, access of air causes it quickly to
acquire an opalescent appearance, from the formation of a
more highly oxygenated and insoluble compound of iron.
This deposits slowly and the water loses its colour. The
objectionable character of such water for washing purposes
is well known.

Odour. — Absolutely pure water is odourless, and, with
rare exceptions, so are all hygienically pure waters. Peaty
waters, especially when warmed and shaken in a bottle with
air, give off a peculiar and characteristic odour. Waters from
certain sources, though quite free from pollution, have an
odour of sulphuretted hydrogen (rotten eggs). Where this
is strong and persistent the water is classified amongst
mineral water as "sulphuretted." In some parts of Essex
the water derived from veins of sand beneath the boulder
clay has a faint but decided odour of this gas; the smell



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QUALITY OF DRINKING WATERS 107

entirely disappears upon leaving the water exi>osed to the
air for a short time in a bucket or tank. In these districts,
however, the inhabitants will drink any kind of ditch or
pond water rather than this, so convinced are they that such
a smell can only proceed from the vilest sources. With
these exceptions any water giving off an odour when warmed
must be considered impure, and therefore inadmissible as a
domestic supply. Odorous waters appear to be much more
commonly met with in some districts than in others. In
Massachusetts, out of 1404 samples of drinking water
examined, from reservoirs, ponds, lakes, rivers and brooks,
only 275 were entirely destitute of odour, 458 had a " vege-
table or sweetish" odour, 202 a "grassy" odour, 84 a
"mouldy" odour, 146 an " aromatic " odour, 47 a "fishy"
odour, 92 a "disagreeable" odour, and 100 an "offensive"
odour. Mr. G^. N. Calkins, who has made a special study of
this subject, concludes that there are three classes of odours : (1)
odours of chemical or putrefactive decomposition, (2) odours
of growth, and (3) odours of physical disintegration — the two
latter being probably due to odorous oils. Theoretically,
the odours of a water may be due to dissolved or suspended
matters of mineral origin, but no such substances are known
to affect great bodies of water. Decaying vegetable matter,
he thinks, is responsible for the "vegetable and sweetish"
odours, and dead animal matter for the " offensive " odours.
The " grassy " and " mouldy " odour cannot yet be explained.
The "aromatic" and "fishy" odours are more important,
since they are prone to develop at certain seasons of the
year in waters which at other periods are quite destitute of
smell. These are invariably surface waters which have been
stored for some time in open reservoirs.

The fishy odour is said to be due to various Infusorians,
one of which, the Uroglena Americana, has during the past
two or three years infested several of the drinking waters of
the State.

Professor Remsen, who investigated the cause of the



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108 WATER SUPPLIES

"cucumber" odour 1 of the Boston water in 1878, attri-
buted it to the decomposition of a fresh -water sponge
(Spongilla fluviatilu). Mr. Rafter attributed the disagree-
able fishy odour and taste of a water which he examined to
the presence of Volvox globator, and I have observed a
similar coincidence in a public water supply in this country.

From time to time an organism "barely visible to the
naked eye," globular in form, greenish yellow in colour, and,
on superficial examination, closely resembling Volvox globator,
has been found in several of the Massachusetts water supplies,
and recently it appeared in great abundance in the ponds
supplying Norwood and Plymouth. The water in the ponds
had no marked odour, but as delivered from the taps in the
towns it had a most objectionable smell. This colony-forming
infusorian was found to belong to the genus Uroglena.
Three species are described, but one only,^ the Uroglena
Americana, appears to impart an odour to water. When in
a state of disintegration it liberates an oil -like substance
with an intensely disagreeable smell. As this species has
frequently been mistaken for Volvox, possibly in cases
where bad odours have been attributed to the latter they
were really due to the Uroglena, Such appears to have been
the case at Middleton and Meriden, Connecticut, in 1889.
The organism was found in great abundance in the reservoirs,
but was absent in the tap water, and the latter alone had
any odour. Apparently while traversing the water-mains
the delicate structure becomes completely disintegrated,
liberating the strongly smelling oily constituent. Bursaria
ga&tris gives a sea-weed like odour, Cryptomonas furnish a
"candied violet" odour, Asterionella and Tabellaria (Dia-
toms) an " aromatic " odour. 2

At Bolton (Lancashire) the water supply in July 1891
gave rise to some alarm, as it had somewhat suddenly acquired

1 "Odours in Drinking Waters": Report of Massachusetts State
Board of Health, 1892.

2 Vide Appendix, "Report of Rotterdam Crenothrix Commission."



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QUALITY OF DRINKING WATERS 109

a "fishy" odour and taste. Dr. Adams, the Medical Officer
of Health, attributed the disagreeable odour to various forms
of fresh-water Algse, but more es|>ecially to Conferva Bom-
bycina, since this species when decomi>osing yields fwtid
gases, " the smell of which resembles that of fish not in very
fresh condition." He regarded the growth as being fostered
by the presence of phosphates derived from manure and
sewage on the watershed area. As fishes feed on such vege-
table matters, Dr. Adams advised stocking the reservoir with
fish, an experiment which has been tried elsewhere, with
doubtful results. At Cheltenham, in 8epteml>er 1891, the
water derived from an uncovered reservoir fed by springs
was found to have acquired this fishy odour and flavour.
These springs supply three reservoirs, A, B, and C. A is
covered over, B and C uncovered. The open reservoir, C,
was the one in which the water was affected, and it was
found when emptied that upon the sides and bottom there
was a considerable growth of Cham fwtuia. Dr. Garrett, the
Medical Officer of Health, says : " This plant is infested at all
times with parasites, but during the time its cells are break-
ing down, the entire bulk of water contained in the reser-
voir swarms with living organisms, varying in size from the
Entomostraca that are easily visible to the naked eye, to the
most minute Protococci and other unicellular organisms which
require a high power of the microscope to be distinguished."
Species of Volvox were very numerous ; sj>ecie8 of Nostoc and
filaments of OBctllatoriaceai were also found. Paramccia,
Vorticellve, Rotifercp, Anguillulcr, were also observed. The
cleansed reservoir was dressed with lime and the water again
turned in. All went well until the corresponding week of
the following year, when the water from the same set of
reservoirs again developed the fishy odour and flavour. This
time, however, it was reservoir B which was chiefly
affected, though the water in C was not destitute of odour.
The water in the covered reservoir, A, remained free from
algoid growth and was odourless. In C Chara was again



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no WATER SUPPLIES

developing, whilst in B the growth was abundant. This,
Dr. Garrett thinks, proves conclusively that the Chara is the
cause of the trouble. It is worthy of remark, however, that
he found Lyngbya muralis parasitic on this plant, and that
Dr. Farlow of Harvard University, in the Bulletin of the
Bussey Institution for 1877, ascribes a peculiar suffocating
odour as being due to the presence of this species of Nostoc
in potable waters. A similar odour, he says, is produced by
other species of Lyngbyce and Oscillatorice, whilst Beggiatoa
(the so-called sewage fungi) gives off a sulphurous odour,
and decaying Nostoc a more disagreeable odour of pig or
horse-dung. Pari passu with the development of the fishy
odour in the Cheltenham water, the amount of organic
matter (as measured by the organic ammonia and the
permanganate required for oxidation) also increased therein,
and to distinguish this from pollution entering the reservoir
from without, Dr. Garrett calls it " natural " contamination.
The Cheltenham water supply is naturally very pure and has
a hardness of 7 to 1 1 degrees. In this latter respect, there-
fore, it differs from the other waters which have been men-
tioned as similarly affected, since all are surface waters of
the softest character. At Gloucester, however, which also lies
in the Severn valley, and which is supplied with a water from
a similar source, there have been from time to time complaints
due to the same cause. Invariably these odours develop in
the autumn, but in certain years only, hence we may reason-
ably infer that the climatic conditions have been especially
favourable for the growth of the particular organism or
organisms which by their metabolic changes, or by their
degeneration or decay, give rise to the foul -smelling com-
pounds which taint the water. The drinking of such
waters is not recorded to have caused any illness, or any
disagreeble effects beyond a sensation of nausea. The water,
however, cannot be considered to be wholesome, and if there
is no alternative supply it should be well filtered and boiled
before use. Boiling alone will, in some cases, entirely remove



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QUALITY OF DRINKING WA TERS 1 1 1

the odour, whilst in others it api>ears to accentuate it unless
the organisms producing it have been previously removed
by filtration.

Small eels have been found in water-maims and these by
their decomposition have been known to impart a disagree-
able odour to the water drawn therefrom. 1

A recent case of somewhat similar character occurred in
a small Essex hamlet obtaining its water supply from a
pond. The water acquired a disgusting odour in the early
summer, and I found that during the previous winter, which
had been very severe, the water had been frozen into one
mass of ice. After the thaw a quantity of dead fish had been
removed, but apparently some had remained in the (>ond, and
with the advent of still warmer weather these were decom-
posing rapidly, and the products of the putrefactive processes
were tainting the water. In another case a water flowing from
a disused mine acquired a most offensive odour ; from the
microscopical and chemical examination of the water I con-
cluded that some animal had fallen down the shaft, which was
on the hill above, and had been killed, and that its body was
decomposing and polluting the water. Dead animals (from
mice to babies) have been found in cisterns and tanks used
for storing water when the development of some peculiar
flavour has caused them to be examined. That putrid animal
matters often contain poisons of the deadliest character is
well known, hence waters containing any products of such
decomposition should be looked upon as especially dangerous.

Taste. — Smell and taste are. often confounded, for many
substances possessing very strong odours, and generally
reputed to have equally characteristic and powerful tastes, are
really tasteless. Vanilla, garlic, and assafoetida may be cited
as examples. If the sense of smell be lost, or be held in
temporary abeyance by closing the nostrils, it will be found
that these substances are perfectly insipid and flavourless.

1 "Eels iu Water -Mains of the East London Waterworks," Local
Government Board Report t 1887.



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112 WATER SUPPLIES

Doubtless many of the waters which have just been referred
to as having fishy, aromatic, or other odours and tastes, are
really tasteless. But odourless waters may affect the sense
of taste. Thus a very small quantity of iron gives water an
astringent inky flavour, whilst an excess of common salt
makes the water saline or brackish. Rain water has a
peculiar flavour, and freshly distilled water is most insipid.
Without having a distinct flavour, however, waters vary much
in palatability. A well-aerated, moderately hard water, such-
as is derived from wells in the chalk and oolite, and from
deep springs, is the most palatable. Upland surface waters
and stored or aerated rain waters are moderately palatable,
whilst fresh rain water and most polluted waters are least
palatable. Some shallow well waters containing very large
amounts of oxidised sewage matters are exceedingly palatable,
and every analyst and medical officer can recall instances in
which such waters have been held in high esteem for their
brilliancy, pleasant flavour, and sparkling character, until
something has occurred which caused the water to be ex-
amined and its true nature discovered. Whilst a good water,
therefore, should be palatable, it does not follow that because
a water is very palatable that it is also very pure and well
adapted for domestic purposes.

Turbidity. — A good drinking water should be quite bright
and free from all suspended impurities. Substances in a very
minute state of division render water opalescent, and settle
very slowly, if at all. Larger particles of mineral substances,
living organisms visible to the naked eye, and vegetable and
animal d6bris, cause a greater or less turbidity according to
the amount present. Very often a water which looks quite
clear in an ordinary tumbler is found to be opalescent or
turbid when viewed in a tube 1 or 2 feet in depth.

Insoluble mineral matters usually deposit rapidly; clay,
however, causes a turbidity which disappears very slowly and
is sometimes very difficult to remove even by filtration. A
public water supply with which I am acquainted was always



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QUALITY OF DRINKING WATERS 113

more or less turbid. It was derived from chains of wells
sunk in loam and sand, and after heavy rains the amount of
suspended clayey matter gave the water a most unsightly
appearance. Many endeavours had been made to clarify the
water, including treatment with alum, and filtration through
sand, vertical sheets of flannel, etc., but without ensuring
really satisfactory results. At my suggestion filter beds were
constructed of polarite and sand, and the water ever since
has been delivered to the consumers in a perfectly clear and
almost brilliant condition.

The nature of the suspended matter can often be dis-
tinguished by the unaided eye, and the trained observer may
draw important inferences from such an examination ; but
more frequently the aid of the microscope has to be invoked
to determine the character of the deposit. Finely -divided
mineral matter brought down by rivers in flood times is said
to be capable of causing diarrhoea (vide Chap. X.). Dead
organic matter, or debris, may be derived from decaying plants
and animals. The presence of cotton, linen or silk fibre, of
potato starch, spiral cells of cabbage and similar plants,
fragments of paper, etc., indicate contamination with sewage,
and therefore that the water is of a dangerous character.
Whatever the source, any considerable quantity of such im-
purities necessarily impairs the quality of the water.

The varieties of living organisms found in water are in-
numerable. Many are so minute as to require the highest
powers of modern microscopes for their detection, and their
identification is a matter of great difficulty and ofttimes im-
possible. These bacteria are probably found in all natural
waters; but, generally speaking, the purer the water the
smaller the number of bacteria it will contain. The purest
deep -well waters are almost certainly entirely devoid of
bacteria whilst held in the pores of the subterranean rocks
from which they are derived, but as raised to the surface of
the earth a few of these ubiquitous organisms invariably gain
access either from the air or from the materials with which

1



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1 14 IVA TER SUPPLIES

the water comes in contact, and then commence to multiply
with inconceivable rapidity. In other waters the number of
bacteria present varies, roughly speaking, with the degree of
pollution, few being found in the purest waters, whilst a
single drop of sewage-polluted water may contain hundreds
of thousands of them. Professor P. Frankland, who has made
a special study of this subject, says : " As regards the nature
of the bacteria found in natural water, they are for the most
part bacilli, micrococci being comparatively rare, whilst
spirilla are not unfrequently discovered, more especially in
impure waters. Upwards of 200 different forms or species
of micro-organisms have been already found in water, and
although by far the majority of these are presumably per-
fectly harmless, a number of well-known pathogenic forms
have also been discovered." Amongst these are the bacillus
of typhoid fever, of cholera, of tetanus, of anthrax, and of
tubercle. Singularly enough these pathogenic organisms retain
their vitality longer when introduced into sterile water than
when added to a natural water containing the ordinary water
bacteria. Exposure to sunshine appears to have a most destruc-
tive effect upon all bacteria, but Professor Frankland thinks
" it can only be in very shallow bodies of water, and in the
superficial layers of deep ones, that it can exercise its power."

The minuteness of these organisms is such that it is
probable that they never occur even in polluted waters in
such quantities as to render it opalescent to the unaided eye.
Doubtless their presence would be revealed in the track of
Professor Tyndall's concentrated ray of light, just as particles
of dust are revealed by a sunbeam.

The presence of the spores and mycelia of the higher fungi
indicates impurity probably derived from sewage, since the
latter invariably contains phosphates, without which these
forms cannot live.

Algse, diatoms, and desmids are found in open wells, ponds,
lakes, and running streams, and, as we have seen, some forms
are believed to be the cause of the peculiar odours some-



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QUALITY OF DRINKING WATERS 115

tiroes developed in practically stagnant water. Apart from
this, their presence is of little importance, more especially as
they are easily removable by filtration. These forms of
vegetable life (unlike most fungi) do not depend upon decay-
ing vegetable and animal matter for their sustenance, whilst
the lower forms of animal life, next to be referred to, can
only exist in waters containing such substances, and which
therefore are more or less impure.

The lowest forms of animal life are only found in waters
containing organic matter in solution. This organic material
may, however, be merely derived from decaying vegetable
matter, such as is found in the water of bogs and marshes,
but these, nevertheless, cannot be considered as wholesome