Selection of Water Supply Pipes in Residences

1. ENTERPRISE DEVELOPMENT ASSOCIATES
Selection of Pipes for Water Supply in Residences
Earlier only GI pipe was available for water supply but now new piping materials are being introduced in
the market making it difficult to chose the best to use in your dream house .
Properties of some of the more common pipes used these days like, CPVC, Composite (PE/Al/PE),
PEX and Stainless Steel have been compared; cost has been analysed based on the length of pipes
and fittings like, bends, tees etc. used in a typical house (excluding CP fittings like angle or concealed
valves, faucets etc. which can vary according to personal preference). Comparison table is attached.
Major observations are summarised below:
1. Water supply pipe like drainage pipes and electrical wires are the arteries of any building supplying
services to a building. These get embedded in the building behind wall and floor finishes and are
hidden from view, but they are expensive and troublesome to replace, therefore reasonable thought
should go in selecting these vital items for your house. Even though the cost of water supply pipes
may be less than 0.5% of the total cost of the house they deserve serious consideration.
2. CPVC has the lowest cost, is easy and quick to install. Pipes which are exposed to sunlight can age
and become brittle. CPVC has been used for quite some time and can be a good choice where
there is a constraint for budget.
3. Composite pipes constructed with a Aluminium layer sandwiched between two PE(Polyethylene) or
PEX(Cross Linked Polyethylene) layers combine the advantages of both metal as well as plastics. It
has thermal expansion close to metal pipes; can be easily bent. making it easy to lay. Recently one
manufacturer has introduced pre-insulated composite pipes. This pipe, though about 4 -5 times
more expensive as compared to CPVC pipes, is an excellent choice for water supply for external as
well as internal use.
4. PEX tubing is the latest piping on the market. It has the unique advantage that it can reduce all
fittings behind the wall to zero and if installed properly can be pulled out like a wire for replacement.
However it cannot be used for external application like carrying water from the Overhead Water
Tank to the toilet. PEX is about 25% to 50% more expensive than Composite pipes.
5. Stainless Steel is an excellent pipe material but seems an overkill in residences.
6. Proper design and workmanship is the key, manufacturers instructions should be strictly followed in
laying and jointing methods for all pipes to perform well in the long run.
The above is based on information from various sources and is being shared in good faith to assist people in
taking an informed decision. For any feedback please contact sudhirgupts@me.com.
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2. ENTERPRISE DEVELOPMENT ASSOCIATES
Comparison of Water Supply Pipes
12
3.1.2.3 Multilayer pipes
Multilayer composite tubes consist of two polymer layers, one of them inside the pipe,
the other outside. These layers are made of polyethylene with a high heat resistance.
The two layers are separated by a central polymer layer made of aluminum. This gives
greater strength pipe and provides an oxygen barrier. Aluminum layer on the outside
and the inside is covered with adhesive layers.
FIGURE 9. Principal scheme of the multilayer pipe
Multilayer pipe produced using TIG-welding (Tungsten Inert Gas). In TIG welding
method uses inert argon gas. With it welded aluminum layer. Multilayer pipe can be
used for hot and cold water and under floor heating.
Multilayer pipes can operate at temperatures ranging from 0 °C to 70 °C. Pipes can
withstand a maximum pressure of 10 bars. For 100 hours for all the life cycle of the
pipe it is capable of operating at a temperature of 95 °C /14./
Multilayer pipes have good UV protection. This allows you to install from the open
way. As with PEX pipe must adhere to the same manufacturer. You have to buy the
pipe, fittings, and tools with a single manufacturer. This is a pretty big drawback.
As well as PEX tubing and copper pipes, multilayer pipes can be in rolls or individual
pieces of straight pipes. This gives us a choice. For laying long lines would be better to
use pipes in the coil to reduce the number of connecting nodes. Coil length may reach
500 meters /14./
CPVC
Composite PEX/
Al/PEX
PEX (for internal
use only)
Stainless Steel
Brand /Series
name
Astral, Vectus,
Supreme, Kisan,
Ashirwad
Kitec, Veiga,
Nexgen, Jindal,
Kan-therm, Vectus
Giacomini, Astral Jindal, Viega
Material of
Construction
Chlorinated Poly
Vinyl Chloride
Multilayer, PEX/
Aluminum/PEX
Cross-linked
polyethylene
Stainless Steel
Jointing/
Connecting
method
Cold solvent
welding
Crimped,
Compression
Crimped,
Compression and
push-fit
Press fitting
Temperature
Range
Can be used for
Cold and Hot Water
Can be used for
Cold and Hot Water
Can be used for
Cold and Hot Water
Can be used for
Cold and Hot
Water
Thermal
expansion, mm in
50 m with 50o C
rise
180 60 500 27.5
UV Resistance,
Exposed
application
Can be used
exposed but
becomes brittle with
time
Can be used
exposed
Cannot be used
exposed, degrades
rapidly in sunlight
No effect
Durability Good Very Good Very Good Very high
Bendability None
Very Good, and
stays in place
Excellent, but
bounces back
None
Pipe Interior
surface
smoothness
Smooth Very smooth Very smooth Very smooth
Chlorine
Resistance
Good Good
Ease of installation
and training of
plumbers
Easy and fast Easy installation Easy installation
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3. ENTERPRISE DEVELOPMENT ASSOCIATES
Advantages
1. Low cost
2. Easy and fast to
instal
1. Combines the
advantages of
both metal and
plastic while
avoiding both of
their weaknesses.
2. Completely
eliminating
oxygen
permeation and
3. Small linear
expansion
coefficient
4. Can be easily
located with
metal detector
5. Kitec has started
making pre-
insulated pipes
which is a big
advantage
1. Practically no
fitting behind the
surface.
2. Manifolds can be
built with isolating
valves for easy
maintenance. So
leakages can be
attended without
shutting down the
toilet.
3. Can be pulled out
and changed like
electrical wiring.
4. Kinks in the pipe
can be fixed by
applying heat.
1. Corrosion
resistance
2. Hygiene and
suitability for
transporting
drinking water,
3. Less prone to
deposit
formation or
bacteria
colonization,
4. Strength and
ductility.
Disadvantages
1. Can become
brittle with age
and UV exposure
2. Since glue can
quickly worsen
over time, CPVC
pipes are more
likely to start
leaking.
3. Care needs to be
taken to account
for expansion in
length by
providing
expansion loops
in longer pipe
runs
1. Degrades with
sunlight therefore
cannot be used
exposed
2. Different pipe has
to be used for
external exposed
piping
3. Pipe length can
be about 20%
more because of
distribution from
manifold.
4. Requires a lot of
predesign and
proper skill for
installation to take
advantage of
ability to pull out
pipe to replace
damaged pipe
1. High initial cost
Price Index 1 4-5 5-8 24
CPVC
Composite PEX/
Al/PEX
PEX (for internal
use only)
Stainless Steel
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