Page 604 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

The City & Guilds Textbook: Plumbing Book 1

A cesspit is an underground tank that stores sewage until the time of its
INDUSTRY TIP disposal. The design of the cesspit will incorporate an inlet pipe but will have no
outlet pipework.
Older cesspits were usually
constructed of brick, but Cesspits must be constructed so that they are watertight, to prevent the
modern ones are made from leakage of any foul water or the ingress of surrounding groundwater.
glass-reinforced plastic (GRP)
(also referred to as ‘fibreglass’). There are problems that may arise, such as overflow of effluent, so cesspits
must be emptied on a frequent basis. This process must be carried out by a
drainage contractor, who will use the principle of mechanical suction to draw
up the contents of the cesspit into a tanker vehicle.
KEY TERM
Leakage is another problem that is more common with brick-built designs
Mechanical suction: because the fabric of the structure can break down, leading to the ingress
suction that is created by an of groundwater and leakage of foul effluent, and resulting in foul smells and
electrical/mechanical pump pollution of the surrounding area. As a result, the use of cesspits is no longer an
installed onto a tanker truck.
option in most instances.
Septic tanks
KEY POINT

In the past, older cesspits A septic tank is a multi-chamber storage tank allowing liquid and solid waste to
had overflow pipes that separate. The liquid is then allowed to flow out of the tank and be disposed of
no longer conform to the separately. First, the sewage enters a settlement chamber, allowing solid waste
recommended current (sludge) to sink and the liquid to rise to the surface. The surface liquid makes
design requirements. contact with oxygen and the organic matter starts to break down biologically.
This liquid still contains sewage but the particles are small enough to be
carried through the discharge outlet and into the ground (soakaway).
INDUSTRY TIP Basic septic tanks only partially treat sewage and discharge effluent of low
quality. In all instances, a sewage treatment plant should be considered as the
Sometimes even the inlet first option. Septic tanks may be installed, subject to consent, in applications
connections to cesspits can leak. where:

● the soil is of suitable porosity
● installation complies with Building Regulations (Approved Document H)
KEY POINT ● the installation will not contaminate any ditch, stream or other
Many areas of the UK watercourse.
prohibit the installation
of septic tanks. Septic tanks must be at least 7 m minimum from buildings and within 30 m of
access for a vehicle if being emptied by pumping truck.

Suitable termination of condensing boiler
KEY TERM

Condensate: the water condensate drain connections
vapour that is present in Condensing boilers, during the course of their operation, make condensate.
the CO emissions resulting
2
from burning gas. As the Condensate is very acidic and needs to be dealt with correctly. The important
flue gases cool down, the points are as follows.
water vapour condenses ● The condensate outlet on boilers will accept 21.5 mm overflow pipe and
back into water droplets
that are collected in the it is strongly recommended that this discharges into the building drainage
boiler and discharged via system. Where this is not possible, it may discharge into an outside drain,
the condense pipework. provided that precautions have been taken to prevent freezing.

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