CHAPTER XXI
WATER SUPPLY-RECOVERY AND RE-USE OF WATER
Water Supply.—A most important point to be considered when choosing a
site for a paper-mill is undoubtedly that of water supply. Water is as im-
portant as transport facilities and the proximity of markets; unfortunately
this has not always been taken into consideration when choosing a site, and
some mills to-day are very hard put to it to find sufficient suitable water for
their requirements.
The ideal water for all requirements of a modern mill is not commonly
met with, and the mill is fortunate which can boast an adequate supply of
water suitable for steam-raising and paper-making purposes.
In the first place it must be borne in mind that a very large quantity of water
is required to produce a ton of paper, no matter of what quality. For the
production of a rag paper 80,000 to 140,000 gallons of water are required per
ton of paper, and a very large proportion of this is irrecoverable and runs to
waste. For newsprint the amount varies from about 2000 gallons upwards,
per ton.
The second point to be considered is the quality of the water, and
in this connection the quality of the papers to be made will be the deter-
mining factor. If the water is very soft, such as water from peaty moors,
it will suit the steam boilers, as it will eliminate both the necessity for
providing a water-softening plant and all trouble with scale in the boilers
and economises.
This water will, however, foul with slime and possibly with iron deposits
many of the tanks and water-pipes in the mill, and, unless it is carefully filtered,
with suspended matter.
Such water has many advantages, but it cannot be made to produce papers
of such a pure and bright colour as other 'harder' waters, and it is usually
necessary to pass it through a series of filters to remove the suspended matter
and to improve the colour.
Where 'surface' water has to be used, unless the qualities of paper to be
made are very low or highly coloured it will usually be found most satisfactory
to filter it, as otherwise the colour of the paper will be at the mercy of the
weather, and floods and other discolorations will have disastrous results at certain
periods of the year.
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