2. Fundamental source of modern standards of public health
• Water supply:
– Public mains
– Private boreholes
– Private reservoirs
• Drainage:
– Domestic drainage
– Public sewerage and waste
treatment
– Private sewage treatment
3. Sources of water
• Public supply:
– Large reservoirs at high level
– Direct extraction from rivers
– Direct extraction from aquifers via
boreholes
• Private supplies
– Boreholes/wells for drinking water
– Private reservoirs for irrigation water
Reservoir/lake
Borehole/well
River
Aquifer
4. Water distribution
• Water moved from source to outlet
by gravity when ever possible.
• Water moved from primary source
to local reservoir/water tower
storage for local distribution
• Water treated by filtration,
aeration and chlorination.
Fluoridation controversial, but
proved to aid tooth health.
5. Local water distribution
• Groups of buildings supplied from
a local reservoir or water tower
• Pipes under ground for mechanical
and frost protection
• Pipes laid in a grid linked to more
than one supply to aid continuity
of supply Local tower
Local reservoir
Main supply
6. Water supply information
• Water supply pipes
are now made of
high density
polythene and are
buried at least
0.75m below ground
for protection
• Older pipe work is
steel, iron and lead.
Its replacement is a
major industrial cost
• Up to 25% of water
is lost through
supply pipe leakage
7. Hard and soft water
• Water from areas of
limestone or chalk are
likely to be “hard”
• Water from areas of
granite or sandstones are
likely to be “soft”
• Hard water contains
calcium salts. These are
if anything beneficial to
health, but they can • Water softeners replace
precipitate out, causing calcium salts with sodium
“furring” of pipe work salts.
with lime scale
• Sodium salts do not
• Calcium salts also precipitate but can be a
interfere with the action health problem for people
of soaps with high blood pressure
• Softened water should not be
used for drinking water.
• Naturally soft water is
perfectly safe
9. Domestic water supply 2: rising cold water main
Overflow to Cold water storage
noticeable tank. Float valve stops
location over filling
“Rising main”
inside the
building for frost
protection Position of
water softener
(if fitted)
Direct feed to Water
kitchen for company
drinking stop tap
10. Internal water pipework
• Internal water supply pipes
generally made of copper
– Corrosion resistance
– Ease of jointing
• Pipes and fittings like taps can be
joined by
– screw compression fittings, strong
but expensive
– Soldered fittings, much quicker and
quite adequate if well made
12. Domestic water supply 3: cold water distribution
Stored cold
water supply
pipe
Feeds to
upstairs
sanitary units
Feed to Feeds to
bottom of hot downstairs
water storage sanitary units,
tank but not to
kitchen sink
13. Domestic water supply 3: cold water distribution
Cold tank is kept
on warm side of
roof insulation
Stored cold
water supply
pipe
Feeds to
upstairs
sanitary units
Feed to Feeds to
bottom of hot downstairs
water storage sanitary units,
tank but not to
kitchen sink
14. Hot water distribution
Safety expansion
Hot water out at pipe rises above
the top of the hot tank
water tank
Hot water to Cold water in at
first floor the bottom of the
hot water tank
Hot water
to ground
floor
15. Hot water distribution
Safety expansion
Hot water out at pipe rises above
the top of the hot tank
water tank
Hot water to Cold water in at
first floor the bottom of the
hot water tank
Hot water boiler
Hot water heating tank water
to ground indirectly. Should
floor be fitted with
safety expansion
valve
16. Hot water, cold water and central heating
Safety expansion Header tank to
pipes keep heating
system full of
water
Pumps to force
heating water
around the system
Rotary valve
directs water from
boiler to radiators
17. Final points on water supply
• All fittings should have their own
isolation valves so they can be
removed without draining the
system
• All pipework should be ventilated
to a high point for safety
• There must be a drain point at all
low points in the system
• All pipework must be protected
from freezing
