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What Comes In, Must Come Out: Home Plumbing

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by Allison Gunkel

It is six o'clock in the morning and you are trying to pull yourself together for work. Mid-shower, you realize something is not quite right. You go through the list ? the coffee is brewing, your slacks are ironed, the kids get to sleep in, the tub is overflowing with your shower water ? wait, what?!

Home's Kitchen Plumbing

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Of all the things that are supposed to be happening at six in the morning, overflowing tubs and backed up drains are not on the list! Finding yourself in any plumbing dilemma is not fun, as plumbing systems are designed to do their jobs without incident. Knowing the basics of your home plumbing can help alleviate stress and sometimes even the cost of necessary repairs if you can do it yourself.

Home plumbing is actually made up of two subsystems: fresh water and wastewater. The fresh water system enters your house from the regular water main and is under immense pressure. It passes the meter that registers the amount you use, and then splits ? one side going to the hot water tank, the other to supply your cold water needs. Your cold water supply is immediately ready for use. Sometimes, before the water supply is split between hot and cold, it will be split for indoor and outside use.

As the water works its way through your house plan, the freshwater runs through two kinds of supply lines. The primary supply lines move the water from the main to your home, and the secondary supply lines are what branch to different fixtures. Plumbing codes specify internal diameters of what pipes to use for specific plumbing sections or functions. Primary lines are typically ? to 1 inch diameter while secondary lines are ? inch diameter. The diameters get smaller as they get further from the main in order to properly handle the water pressure.

The wastewater subsystem is completely separate from the freshwater system and does exactly what its name infers: it removes wastewater from the home. As the pressure from the freshwater system runs water through a fixture, the flow is strong enough to push the wasted water through the trap. The trap is the curved or S-shaped pipe connected to the drain, right under your water fixture. It is designed to retain a small amount of the water pushed through, to keep sewer gas from rising back through the pipes into your home. Kitchen sinks often have a grease trap, toilets self-trap, and bathtubs utilize a drum trap that collects hair and dirt that would otherwise cause backups. Every fixture must have a trap to be considered functional.

Home Bathroom Plumbing

Once through the trap, wastewater passes through a T-shaped pipe, one branch going up and the other down. The upward branch is used to vent the system; air pressure must be released or the downward flow would be lost. It also passes other T-shaped pipes referred to as "clean outs" or a sanitary "T". The stem of this "T" is at a forty-five degree angle with a cap on the end. These clean outs provide access for drain cleaning systems should a clog form. Due to these T-shaped pipes, the wastewater system is often referred to as the Drain-Waste-Vent (DWV) system. Each part of this system is vital to high performance plumbing.

Knowing how the water systems work is important, but knowing what pipes to use in each case is vital to the quality of your plumbing as well as to the safety of you and your home.


  • Increases the value of a home
  • Does not contain lead
  • More form fitting and smaller diameter allows it to be used in tight spaces
  • Biostatic ? it inhibits bacteria growth, making water safer to drink (though there are some complaints of metallic taste)
  • More resistant to flame and earthquakes than other materials
  • Fails when water temperature rises above 180 degrees
  • Condensation can form inside and freeze pipes, blocking water flow
  • Can be costly to install and repair in comparison to other materials

PVC (polyvinyl chloride)

  • Most lightweight material ? easier to install
  • Least expensive
  • Can withstand higher water pressure with less noise
  • Non-conductive, eliminating rust and condensation issues
  • Self-insulating material can withstand higher water temperatures
  • Less flame resistant
  • Only ? to 2 inch sizes; inflexible with bulky joints
  • Not environmentally friendly


  • Steel or iron coated with Zinc to prevent corrosion and mineral deposits within lines
  • Contains lead
  • Corrodes quickly despite Zinc coating
  • Deposits build up, blocking flow
  • Is not often used in newer homes, but is usually preferred over PVC
Double sinks accent bathroom decor

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Wastewater systems typically use ABS pipe, cast iron, or galvanized pipe. ABS is preferred for its low price and easy installation, but cast iron is quieter. Galvanized is sometimes used with cast iron for vents or smaller drains. However, it is vital to seek advice from a professional when considering mixing kinds of pipes within a system. It is best that one type of pipe is used to ensure safety and quality. For example, mixing copper and galvanized steel causes a chemical reaction ? they cannot be used together.

Pipes are not the only part of the plumbing system within your home; without fixtures, your water would be carried all over but would be inaccessible. Fixtures are the links in the systems, and the one piece of plumbing everyone pays attention to. Plumbing fixtures range from seemingly insignificant to ornately decorative, truly adding to the d?cor of a home.

Faucets, Sinks, Toilets and Tubs

The new trend in custom bathroom and kitchen fixtures is the smart technology of touch controlled or touchless faucets. Sensors are used so that the faucet can detect if something is placed underneath it in need of rinsing, or can turn on and off with a slight touch to the fixture. This technology is fantastic for conserving water and including universal design into aspects of the home that are often overlooked.

Sinks are including different kinds of dividers for the basins, increasing functionality and giving a modern look with a minimalist feel. Kitchen sinks can utilize pot-filler/long-necked faucets that can extend over the stove, eliminating dangerous movement of heavy pots. Side and pull out sprayers with easy to control water pressure ranges are also essential in many new kitchens. Toilets, too, have come a long way with water saving designs and tankless models.

Showers and bathtubs are being divided into separate entities, helping to add to the retreat ambiance desired in many home bathrooms. Thermostatic shower valves allow programmed preferences of temperature and water pressure to be set and recalled later by any individual. Multiple showerheads or body sprayers are typical in new bathrooms, each having numerous spray patterns to choose from. Rain showers that simulate the sound and feel of a spring rainshower are popular for homes today as well.

prep sink with an open kitchen design

Bathtubs have evolved into luxury hot tubs with bubbles. Many are freestanding models that can be placed at any point in the room. These too come with multiple faucet heads, jet patterns, and therapeutic options like massage motions, music preference, and temperature adjustment. Bath toys are obviously no longer about the rubber duckies.

Tankless Water Heater

With all the plumbing fixtures that have been turned into high-tech gadgets, it is hard to say what is more popular. However, one fixture is desired by most all homes, even those without the pricey bathroom spa retreats ? tankless water heaters. These water heaters do not store water and heat it to a specific temperature. Instead they flash heat water, as it is needed, by passing it through a copper heat exchanger. When the tap is turned on, flow sensors signal the burners to fire. When the tap shuts off, so does the entire heating system ? no pilots are left to burn. These systems are compact, freeing up floor space and even hiding out of sight in a closet for the entirety of their longer life span.

Tankless water heaters are not for everyone though. The difference between the incoming water temperatures to the desired water temperature is called the rise. The higher the rise, then the lower the flow rate of your water. In cold climates, the rise tends to be a much higher number, resulting in a low flow or low water pressure. For some people this is bothersome and a tankless water heater is not adequate for their home plan. Also, the amount of hot water the tankless water heaters can provide depends upon the size of the heating element? ? some homes may require larger heating elements that can increase the overall cost of the system. Tankless water heaters cost more up front (2 to 3 times as much as a typical heater), but some areas offer tax incentives or rebates for energy efficient water heaters, which could apply to your tankless model.

Plumbing is one aspect of home design that is basically straightforward but can quickly become complex. Knowing the basics can allow any home-repair challenged individual to fix minor problems on their own, saving quite a bit of time and money. If you do endeavor to make your own repairs, research the project before you start out, including situations that can go wrong and how to respond quickly without further damage. Know where your main shut-off is located, as well as individual shut-offs for each fixture. Turning off the water to the specific area is usually adequate when making repairs, but quickly responding to unforeseen problems by shutting off the main valve can make all the difference between having a flood in your bathroom or a small, trouble-free puddle.

Though plumbing is installed to last for quite some time with minimal incident, hiring a professional is typically recommended for moderate to large repairs or installations, especially when new, technologically advanced fixtures are involved. With a little research, and perhaps just a quick emptying of a trap or clean out, you will be back to your early morning showers, again worrying only about the coffee, your pants, and the kids.

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