160 
J. HOPKINSON-WATER AND WATER-SUPPLY 
which, being almost entirely derived from the overflow of our chalk 
reservoir, is nearly as hard as that obtained direct from the chalk, 
and mixing the two waters, mucl\ the larger proportion being the 
soft water from a distance; (2) by the adoption, universally, of 
a constant supply, and the consequent removal of all lead cisterns. 
Existing lead pipes will be sufficiently well protected by their 
present coating of lime, but all new pipes should, where possible, 
be of iron. Eut in any case there should be a constant supply, which, 
by the necessity for the employment of better fittings, and by less 
waste in taps not being turned and left open when the water is 
turned off at the main, to run to waste when it is turned on again, 
has been found rather to tend to economy in water than to an in¬ 
creased consumption. Cisterns are the great source of danger, for 
however pure the water may be that is sent into them, after 
standing for a time it is almost certain to become contaminated. 
The enormous cost of the construction of a conduit from North 
Wales to London would be nothing to the advantage of the acqui¬ 
sition of a practically unlimited supply of such pure water as our 
mountain-lakes afford, taking into consideration the great wealth 
of London, and in course of years the cost would probably be 
covered, or at least the interest on the outlay would be covered by the 
saving in soap, and by the water being used in manufacturing 
processes for which our present hard water is unsuitable. Since 
Glasgow has had a soft-water supply it is estimated that £36,000 a 
year has been saved in soap. At the same rate London would save 
from a quarter to half a million a year. The actual saving would 
probably be at least half a million sterling per annum, for the 
water London is supplied with is harder than that formerly supplied 
to Glasgow. It has been shown that for every 1000 gallons of 
water used daily for washing and other purposes for which soap is 
employed, a saving of £146 per annum in soap at 4 d. per lb. would 
be effected by using lake water in place of water of 18 degrees of 
hardness.* Presuming that our five and a half millions of people 
each use with soap a gallon of water daily, the saving by substi¬ 
tuting lake water for water of the average hardness of the present 
London supply (about 16 degrees, per 100,000), would be nearly 
three-quarters of a million per annum. 
For such purposes as watering roads and flushing sewers an 
ample supply of water could still be obtained from the Thames. 
Although I do not think it feasible to introduce a dual supply into 
dwelling-houses, part for drinking and part for other purposes, I 
do not see why we should water our roads and flush our sewers 
with water of the purity required for drinking, if we can obtain 
for such purposes a less pure supply at less expense, such as Thames 
water unfiltered. 
Such questions as these, however, are merely matters of detail, 
and I only allude to them to show that there is a way out of the 
present difficulty of supplying London with water, without in¬ 
creasing the serious injury that is now being done to our county. 
* See Parry’s ‘ Water: Its Composition, Collection, and Distribution,’ p. 46. 
