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In kutcha roadside drains care must be taken that, in the process of cleaning, which generally consists in the removal of the bed, they do not in time become permanent roadside trenches without fall; it is much better to have no drains at all than this; mere depressions which, when dry, can be swept, and which will be washed clean after a heavy shower of rain, are much preferable. The proper bed-level of a kutcha drain should be permanently marked by wooden pegs driven well into the earth, and built into a masonry pillar, 1 foot 10 inches square, or by masonry profiles, at intervals of 100 feet apart; this shows at once if the bed-level or section has been unduly lowered during the process of cleaning out.

Flushing.

When designing a drainage system for a town it is essential that provision for flushing be made at the same time, otherwise the drains become receptacles for filth for about two-thirds of the year. This can be arranged by the construction of flushing tanks, which, when full automatically discharge into the drains, by water mains laid underground discharging into the head or summits of the drains; and also by the drains being divided up into convenient sections by stops or sluices, which are lifted automatically, or by manual labour, when the section is full of water, thus ensuring an effective flush.