Drainage systems can be classified into the rain-water
pipe system and sewage pipe system. The integral parts
of a drainage system comprise the drain pipes, traps and
manholes.
Drain pipes should by no means be connected in an improper
way, e.g. sewage discharged from sinks should not be emptied
into any rain-water pipe.
Drainage outlets should be clear of rubbish or fitted
with gratings to prevent rubbish from blocking the pipes.
All drain pipes, including soil pipes, waste pipes,
ventilating pipes and underground drain pipes should be
maintained in good working order without defects. All
such pipes should be inspected regularly, and where leakage,
blockage or defects are detected, they should be rectified
immediately.
In order to prevent putrid air and insects in the soil
pipe from entering the premises, sanitary installations
including hand basin, sinks, bathtubs and showers toilets
and floor drains should be fitted with a trap (U-shaped
water trap, bottle traps or anti-siphon traps). If the
installation is not used regularly, pour about half a
litre of water into each drain outlet once a week. Then,
pour a teaspoon of 1:99 diluted household bleach solution
into the drain outlet. For floor drains, spray insecticide
into the drain outlets after cleansing.
Manholes should be checked regularly and any blockage
detected should be dealt with immediately.
Manholes should be readily accessible for regular maintenance.
Access to them should not be obstructed by floor finishes,
planters or furniture items. Foul air leaking from manholes
can be stopped by using double seal type manhole covers,
or repairing the edges of the manhole openings or cracks
in the manhole covers.
Responsibilities for repair and maintenance of the drainage
system is determined on whether the defective section
of the pipe is for common use or for individual use. For
example, if a rain-water pipe bursts, the owners' corporation
or all owners shall be liable for repairing it. However,
if a branch pipe connected to an individual flat is damaged,
the owner or occupant of that flat shall be responsible
for repairing it.
