The Troubled Water Question
The order to drive to Kew Bridge, was obeyed in capital style; for in three-quarters of an hour we were deposited on the towing path on the Surrey side of the Thames, opposite the King of Hanover's house, and a quarter of a mile west of Kew Bridge.
'Here,' I explained 'is the spot whence the Grand Junction Company derive their water. In the bed of the river is an enormous culvert pipe laid parallel to this path. Its mouth—open towards Richmond—is barred across with a grating, to intercept stray fish, murdered kittens, or vegetable impurities, and —except now and then the intrusion edgeways of a small flounder, or the occasional slip of an erratic eel—it admits nothing into the pipe but what is more or less fluid. The culvert then takes a bend round the edge of the islet opposite to us; burrows beneath the Brentford road, and delivers its contents into a well under that tall chimney and taller iron "stand-pipe " which you see on the other side of the river.'
'And is this the stuff I have to pay four pounds ten a year for? ' exclaimed Mr.Lyttleton, contemplating the opaque fluid; part of which was then making its way into the cisterns of Her Majesty's lieges.
'Certainly; but it is purified first. We will now cross the bridge to the Works.'
Those of my readers who make prandial expeditions to Richmond, must have noticed at the beginning of Old Brentford, a little beyond where they turn over Kew Bridge, an immensely tall thin column that shoots up into the air like an iron mast unable to support itself, and seems to require four smaller, thinner, and not much shorter props to keep it upright. This, with the engine and engine-houses, is all they can see of the Grand Junction Waterworks from the road. It is only when one gets inside, that the whole extent of the aquatic apparatus is revealed.
Determined to follow the water from the Thames till it began its travels to London, we entered the edifice, went straight to the well, and called for a glass of water. Our hosts—who had received our visit without hesitation—supplied us. ' That,' remarked one of them, as he held the half-filled tumbler up to the light, ' is precisely the state of the water as emptied from the Thames into the well.'
It looked like a dose of weak magnesia, or that peculiar London liquid known as 'skim-sky-blue,' but deceitfully sold under the name of milk.
'The analysis of Professor Brande,' said Lyttleton, ' gives to every gallon of Thames water taken from Kew Bridge, 19.2 parts of solid matter; but the water, I apprehend, in which he experimented must have been taken from the river on a serener occasion than this. To-day's rain appears to have drained away the chalk—so as to give in this specimen a much larger proportion of solids to fluids than his estimate.'
'In this impure state,' one of the engineers told us, ' the water is pumped by steam power into the reservoirs to which you will please to follow me.'
Passing out of the building and climbing a sloping bank, we now saw before us an expanse of water covering 3 ½ acres; but divided into two sections. Info the larger, the pump first delivers the water, that so much of the impurity as will form sediment may be precipitated. It then slowly glides through a small opening into the lesser section, which is a huge filter.
' The impurities of water,' said the barrister, assuming an oratorical attitude, to give us a taste of his ' reading up,' 'are of two kinds; first, such as are mechanically suspended—say earth, chalk, sand, clay, dead vegetation or decomposed cats; and secondly, such as are dissolved or chemically combined —like salt, sugar, or alkali. Separation in the one case is easy, in the other it involves a chemical process. If you throw a pinch of sand into a tumbler of water, and stir it about, you produce a turbid mixture; but to render the fluid clear again you have only to adopt the simple process of letting it alone; for on setting the tumbler down for awhile, the particles—which, from their extreme minuteness, were easily disturbed and distributed amidst the fluid—being heavier than water, are precipitated, or in other words, fall to the bottom, leaving the liquid translucent. This is what is happening in the larger section of the reservoir to the chalky water of which we drank. I think I am correct? ' asked the speaker, angling for a single ' cheer ' from the Engineer.
'Quite so,' replied that gentleman.
'Provided the water could remain at rest long enough—which the insatiable maw of the modern Babylon does not allow,'—continued the honourable orator, rehearsing a bit more of his speech, ' this mode of cleansing would be perfectly effectual. In proof of which I may only allude to Nature's mode of depuration, as shown in lakes—that of Geneva for instance. The waters of the Rhone enter that expansive reservoir from the Valais in a very muddy condition; yet, after reposing in the lake, they issue at Geneva as clear as crystal. But so incessant is the London demand, that scarcely any time can be afforded for the impurities of the Thames, the Lea, or the New River to separate themselves from the water by mere deposition.'
'True,' interjected one of the superintendants. 'It is for that reason that our water is passed afterwards into the filtering bed, which is four feet thick.'
'How do you make up this enormous bed?'
'The water rests upon, and permeates through, 1st, a surface of fine sand; 2d, a stratum of shells; 3d, a layer of garden gravel; and 4th, a base of coarse gravel. It thence falls through a number of ducts into cisterns, whence it is pumped up so as to commence its travels to town through the conduit pipe.'
We were returning to the engine-house, when Lyttleton asked the Engineer, 'Does your experience generally, enable you to say that water as supplied by the nine companies, is tolerably pure? '
'Upon the whole, yes,' was the answer.
'Indeed! ' ejaculated the orator, sharply. ' If that be true,' he whispered to me, in a rueful tone, 'I shall be cut out of one of the best points in my speech.'
'Of course,' continued the Engineer, 'purity entirely depends upon the source, and the means of cleansing.'
'Then, as to the source—how many companies take their supplies from the Thames, near to, and after it has received the contents of, the common sewers? '
' No water is taken from the Thames below Chelsea, except that of the Lambeth Company, which is supplied from between Waterloo and Hungerford Bridges; an objectionable source, which they have obtained an act to change to Thames Ditton. The Chelsea Waterworks have a most efficient system of filtration; as also have the Southwark and Vauxhall Company; both draw their water from between the Red House, Battersea, and Chelsea Hospital. The other companies do not filter. The West Middlesex sucks up some of Father Thames as he passes Barnes Terrace. Except the lowest of these sources, Thames water is nearly as pure as that of other rivers.'