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This page was last revised on December 30, 2004.
- When deciding what to use for water supply plumbing, your choices are few. The oldest
homes were plumbed with lead pipe, which is a BAD idea. Then threaded galvanized steel pipes
were used, which are still available. Then copper became the standard. Next, CPVC
(chlorinated polyvinyl chloride) plastic became available. PVC (polyvinyl chloride) can be used
for cold-water supply. Lately, mobile homes have been plumbed with "Qest" plastic, a type of
polyethylene. My recommendation? Without a doubt, it's copper. Here are the characteristics
of some of these:
- Copper: This has the advantage of being rigid, and resistant to being damaged. It's
fairly easy to repair, and doesn't adversely affect the water it contains. Older copper piping was
soldered together with lead solder, which could leach into the water in the pipe. Now, it's illegal
to use lead solder for these pipes, and there is no dangerous leachate into the water. However,
don't worry too much if you have older copper plumbing. After the first few years, the amount
of lead leached into the water drops substantially. If you're concerned about lead, then simply
run the water for a minute or so before using any for drinking or cooking purposes to flush the
pipes first. Copper also provides an easy way to ground anything in the house and to ground the
whole house itself.
- PVC (polyvinyl chloride): PVC pipe is usually white, and for pressure may be
schedule 40 or schedule 80. However, PVC cannot be used for hot-water piping because it will
warp or even burst. It is also not particularly rigid in small sizes, and can be easily damaged by
pounding nails into the wall or drilling. There is also evidence that it leaches into the water.
- CPVC (chlorinated polyvinyl chloride): CPVC is a sort of ecru, or light tan, color.
It may be used for hot-water plumbing as long as the water is no hotter than 120 degrees or so. It
is not very rigid, however, and is as prone to damage as PVC. Again, it may be leaching into the
- Galvanized Steel: Galvanized steel actually is excellent for water-supply plumbing
when it's fairly new. Because of its threaded nature, it's a lot of work and difficult to assemble.
However, when it eventually starts rusting internally, it becomes clogged and must be replaced,
which is a monumental job.
- Qest: Quest is the least rigid of all these types, and has all the disadvantages of the
other plastics. In addition, it is difficult to work with and to keep properly sealed against
It can't just be glued like the other plastics but relies on pressure-type fittings. I detest the stuff.
- NEVER mix steel and copper plumbing directly; you'll get something called galvanic or
electrolytic action that will corrode both metals rapidly, quickly clogging the pipes. Also, do
NOT use black steel piping; this is intended for natural gas use only. If you need to patch
together copper and steel, then use what's called a dielectric nipple or use a plastic adaptor
fitting in between to avoid the galvanic corrosion.
- When soldering copper pipe, carefully follow these steps:
- Before preparing to solder pipes and fittings, cut the pipe to size and assemble everything to
make sure that it will fit properly. Use a good pipe cutter to cut the pipe, and make sure that it
has a sharp, well-fitting cutting wheel in it. Lightly clamp the cutter onto the pipe, and twirl it
around the pipe in a circular motion. Make sure that you push it straight around the pipe, and
make sure after one revolution, that it meets the first part of the score. If it doesn't, then try
turning the cutter the opposite direction. If you just can't get it to go straight, then you probably
have a really cheap cutter, or it's damaged, or it's got a bad wheel. For cutting existing pipe that's
already installed, use a mini-cutter. Quality in a cutter is actually quite important.
- Use a wire brush, made for the purpose, to clean the insides of the fittings. Turn it in a
circular motion, and make sure that the entire contact surface inside the fitting is brushed and
- Use a different type of wire brush, again made for the purpose (combination wire brushes
that have both types in one tool are also available), to clean the outside of the pipe where it will
fit into the fitting, or use plumber's emery cloth. This is a type of sandpaper that comes in coiled
strips, and you just tear some off to use. Wrap it around the end of the pipe and turn it to clean
it. Again, the entire end of the pipe that will be going into the fitting, plus a little beyond that,
should be clean/shiny when you're done. If cleaning old pipe, the emery cloth will work much
better than the wire brush.
- Use a small flux brush (or a corner or a rag, or even a CLEAN finger) to coat both the inside
of the fitting and outside of the pipe in the cleaned area with flux. The flux must be a high-
temperature flux intended for lead-free solder. It only takes a very small amount of flux, but it
should be applied evenly and completely.
- Fit the pipe together. Never prepare more joints than you can solder quickly, but always
solder all joints in a single fitting at the same time. In other words, if soldering a tee, then make
sure that all three pipes going into the tee are being soldered at the same time.
- Using your propane torch, heat the fitting evenly. Play the flame over the fitting, trying to
reach all parts of it. The very tips of the blue cones of the flame should be at the metal. Always
heat the fitting, not the pipe: thus, the fitting is hotter than the pipe, and has expanded more than
the pipe during heating, so that as it cools with the solder, you have a good compression joint as
well as a solder-type metal weld.
- When the solder melts spontaneously on the surface of the copper, without putting the flame
to it, then solder the joint. Touch the tip of the solder to the crack of the joint, playing it around
as far as convenient until you can see that the solder has flowed all the way around the joint.
This is done without the flame.
- Then solder the other outlets of the fitting.
- Immediately take a reasonably clean rag and wipe around the joint to smooth out excess
solder and remove excess flux. Let the joint cool.
- When repairing copper pipe that has already been carrying water, it's important to drain it
out thoroughly first or you'll never get the pipe hot enough to get a good solder seal. Open the
highest-level taps in the house for the water line, as well as the lowest ones, to drain out as much
water as possible. Then make your cuts in the pipe to prepare for the repair. Next, plug the pipe
to stop water drips after you've drained out as much water as possible. A quick and easy way to
do this is to take a slice of store-bought white ("balloon") bread, wad it up, and shove it back into
the pipe firmly. When the water is turned back on, the water will easily dissolve and flush out
the bread. Gelatin plug kits are also available at hardware and building supply stores.
- Each plumbing fixture and appliance in the house has a trap. It's part of the body of the
toilet, but for most fixtures and appliances, it's part of the plumbing beyond. The trap is a sump,
or dip in the plumbing, that always holds water so that it makes an air seal between the inside of
the house and the sewer system (or septic system). This prevents sewer gases from coming into
the house. Sewer gases can actually be very dangerous as well as obnoxiously smelly; they can
asphyxiate people or even explode. The traps also helps keep the heat in the house in the winter
and to keep vermin out all year-round. It's important that all traps have water in them at all
times. However, if there is a sink, floor drain, washing machine outlet, toilet, or other item that
is not being used, the water in the trap may dry up. It's a good idea to pour water through any
unused traps at least twice per year. It also may be a good idea to add a capfull or two (CAPfull,
NOT cupfull) of bleach to the trap for disinfection.
- There are actually four type of plumbing in the average house. The water supply plumbing
is only one of the four. The other three are: waste, drain, and vent. You will see some plumbing
fittings designated "DWV," which means "drain/waste/vent," and means that the fitting is
approved for all three uses. These three types of piping usually all connect together. The pipes
that carry away waste water from fixtures such as toilets and sinks are the waste pipes (the actual
waste from a toilet is called "soil"). Drain pipes are only those that directly serve to carry away
stormwater or water from floor drains. Vent pipes connect to waste pipes, and sometimes drain
pipes, to provide a source of air and a place for gases to go. Each waste pipe from each fixture
in the house is supposed to have an individual vent pipe attached beyond the trap. These vent
pipes attach together when they are at least six inches above the "flood rim level" of each
fixtures, to make sure that they never become waste pipes. The vent pipes provide a source of
air flow so that flowing waste water don't suck traps dry, and also provide a place for sewer
gases to go so that they don't push their way into the house through the traps. Vent pipes that
pass through the roof should always be at least three inches in diameter to prevent icing-up
- In the past, DWV systems were made of cast-iron "soil pipe." However, the soil pipe does
eventually corrode away, and it's very heavy and hard to work with. Today, DWV plumbing
systems are usually made of PVC (polyvinyl chloride). Schedule 40 DWV is required for waste
systems. Lighter weights (Schedules 20 and 30) are strictly for vent and drain systems, not
waste. The heavy schedule 40 is very strong and rigid and does not clog or corrode. Also used
sometimes is ABS (acrylonitrile-butadiene-styrene), but it is not as common or reliable.
- To properly glue together PVC, the ends of the pipes should be first cut square. Many
people find this difficult. Usually, a hacksaw is used. However, a circular saw or chop saw may
also be used, and many people find it much easier to properly cut the PVC with one of these
tools. Then, a cleaning solvent should be used that's made for the purpose. Both the surface of
the inside of the fittings and the corresponding surface of the outside of the pipe should be
thoroughly cleaned with the cleaner. This both cleans the surfaces so that the glue will hold
better, but also softens the plastic itself so that the glue will properly weld it together. Then, the
glue should be applied to completely coat both surfaces, and the pieces should be fitted together
with a twisting motion until completely seated.
- When installing a water heater, use heat-trapping nipples in the top. These are usually sold
in pairs, and feature internal ball valves that automatically open to allow water to flow, but close
when no water is flowing. These reduce heat loss from the water heater. They usually also are
configured to stop galvanic action. Also use unions (two sweat or thread fittings that fit together
with a smooth interface, and a nut then clamps them together) so that the water heater may be
easily connected to and disconnected from the system.
- adaptor: a fitting that either provides a way to change the size of the pipe (reducing
coupling), or that provides a way to change the type of pipe
- appliance: in plumbing, a device that uses water and attaches to the plumbing and uses an
external source of power, such as a dishwasher, washing machine, or water heater. Also see
- bend: see ell
- bibb: see hose bibb
- boiler drain: a stop valve similar to a hose bibb, but with a male thread (outside, or exposed,
- cap: a fitting with only one hole, that fits over the end of a pipe to close it off. Also see
- cleanout: a fitting that attaches to a pipe that has a threaded plug (or cap) that can be
removed for cleaning purposes
- coupling: a fitting with two holes that permanently joins together two pipes.
- ell: also called elbow, a fitting with two openings and a bend between, for changing
direction in pipes. A right-angle ell is called a 90-ell, and a 45-degree ell is called a 45-ell. In
DWV plumbing, 90-ell is also called a quarter bend, and a 45-degree ell is similary called an
eighth-bend. There are also a 60-degree fitting called a sixth-bend and a 22.5-degree fitting
called a sixteenth-bend.
- fixture: any plumbing device that uses water for a specific purpose but has no powered parts,
such as a toilet, lavatory, tub, shower, or sink. Also see appliance
- flange: a fitting that features a flat part so that it can be fastened down with screws or nails
- flood rim level: the level at which a fixture, when filled with water, will overflow
- flux: a paste or thick liquid that is applied to metal before soldering, and which etches the
surface of the metal and helps the solder to flow and adhere to the metal
- frostproof valve: a hose bibb that features a long stem, so that the valve is inside the house
while the handle is outside the house, and so that any water remaining on the outside of the valve
automatically drains out whenever the valve is shut
- gate valve: a valve that opens and closes by moving a solid piece of metal that fits tightly
against machined surfaces
- hose bibb: a stop valve with a female thread (inside thread), and with a flange for mounting
- lavatory: a bathroom sink. Also sometimes used for the bathroom itself. It is NOT the
- leader: downspout from guttering
- nipple: a short piece of threaded pipe
- plug: a fitting that fits inside the end of a pipe to close it off
- soil: the waste from a toilet
- solder: a mixture of soft metals that melts at a low-enough temperature that it can be used to
provide a seal by adhering to harder metals
- stop: a type of valve that closes off by means of a rubber washer that provides a seal under
- supply: a tube that carries a fresh water supply from a stop valve to a faucet or other
- tee: a plumbing fitting with three openings, so that three pipes may be fitted together
- trap: a compound bend in a pipe that provides a low point where water stays to provide an
- union: a fitting that joins together the ends of two pipes, which features two parts that fit
together with a threaded collar to clamp the ends together. The union enables the pipes to be
tightly joined but also makes it easy to take them apart when necessary.
- vent: a pipe for connecting waste/drain plumbing systems with the outside air
- waste: drainage from plumbing fixtures
- water closet: toilet
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