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Most people take for granted the benefits of plumbing systems and fixtures—carrying the drinking water to, and the waste water away from, your home. But even more people seldom consider the various components and issues involving plumbing. The following pages outline various components and key considerations to help you evaluate your system.

The purpose of the plumbing system is to provide an adequate supply of potable water and to properly dispose of waste products.

Domestic Water Supply — Source

Public Water Supply (city water)

To determine if the property uses city water, the best indication is a water meter. In older constructions, the water meters might be located outside in a front yard pit or at the front curb. In modern construction, water meters are usually located inside the basement, frequently with a remote digital reading device located on the outside of the building.

Types of Water Supply Lines

Copper Piping

The most common type of water supply piping is copper piping. This piping is used both to supply the water from the street connection at the municipal connection to the dwelling as well as in the interior of the house for supplying fixtures. It is important that the copper piping not be kinked as this will reduce water flow. Residential service piping is typically 3/4 inch. Larger homes may have 1 inch or larger. The horizontal supply piping is generally 3/4 inch with 1/2-inch risers to fixtures. Smaller homes or homes with one bathroom may have 1/2-inch supply piping.

Copper is a very dependable material, however, if the water is supplied by a well and the water is acidic or has a low pH level, the acidic water degrades the copper. When the walls of the pipe wear thin, the failures will look like tiny, round, green patina stains. If these stains are ignored, water may spray through the hole in the center of the round stain. This problem is generally due to the acidic water, which should be neutralized.

Water hammer, otherwise known as the banging noises made when water flow is stopped abruptly, is not unusual when metal pipe, such as copper or steel is used. The momentum of the water flow stoppage makes the noise. One solution is to provide an air cushion or shock absorber that will soften the movement or momentum of the water. Some water supply systems have air tubes or diaphragm appliances installed in the piping system to prevent hammering.

Polybutylene Piping (PB)

Polybutylene piping is gray plastic piping that is very flexible, with joints secured with either epoxy or insert fittings and metal crimp rings. This material has been known to be defective at the junctions. Barbed brass or copper insert fittings with crimp ring joints are generally more dependable than the epoxy joints. The joints are vulnerable to chlorine in the water, which causes deterioration. The insert fittings have been in use since 1986 and are still in use today.

Most municipalities do not allow certain types of Polybutylene piping to be used for residential potable water. There have been individual as well as class action lawsuits concerning certain manufactures of this product.

The major manufacturers of PB piping were Quest and Vangard. Since they can no longer purchase the resins necessary to produce this material, they have begun production of PEX. Which is a type of Polybutylene that is acceptable for potable water use in most areas.

A second type of polybutylene piping is “Big Blue”. This piping is typically utilized in the main water supply to the house. Its name was derived from the color of the material. The material was an inch and half to 2 inches in diameter and was rated for cold-water installation only. The major problems that have occurred with this type of PB are related to poor installation practices.

Galvanized Steel Water Service and Supply Piping
Galvanized steel piping is still in use, however, it is not installed in modern construction. It oxidizes from the inside out, the oxidation (rust) reduces the interior diameter of the pipe, restricting the flow of water and it usually first leaks at threaded joints where the pipes are joined. This is analogous to hardening of the arteries in humans. Adequate water supply can normally be restored, to some extent, by replacing the horizontal supply piping in the basement (assuming they are accessible) with copper piping. Replacing the vertical risers in the walls is much more difficult and expensive than accessible horizontal piping Replacing all of the older galvanized steel piping would be the most desirable solution but the most expensive.

If the supply piping from the municipal water lines is galvanized steel, it is likely that the service piping is also galvanized steel. Galvanized steel piping fails sooner at the heavier used fixtures (i.e. the kitchen sink and the main bathroom). Failures are usually related to the amount of oxygen that is present. The more a fixture is used, the more water (and oxygen) is present, which corrodes/oxidizes the piping at a greater rate.

First clues of failure in the piping are roundish rust growths, commonly called rust warts, on the outside of the pipe. These are failures that have come through the pipe. It is not unusual for the corrosion to seal the failure.

Polyvinyl Chloride Piping (PVC)
PVC piping is approved for cold water only. Chlorinated polyvinyl chloride (CPVC) is approved for cold water and may be used for hot water, but not over 140° Fahrenheit. PVCs are joined with a primer and solvent cement. PVC piping is not a conductor and cannot be used for an electrical ground.

Polyethylene Pipe (PE)
Polyethylene piping is typically used as service piping. Generally black in color, it is a flexible material that is easier to install than most other service pipings. Joints in PE piping may not be made with adhesives or solvent cements. Joints should have two stainless steel band clamps, but the connection to metal (such as copper) is typically made with one clamp. The fittings have a smaller interior diameter than the piping. Therefore, PE must be sized based upon the fittings. This material is approved for cold water installation only and is very often found on well water installations.

Lead Piping
There is very little lead supply piping in use, however, you may see some lead service piping in 100 year-old inner city neighborhoods. The prominent concern is the probable 6-inch to 8-inch municipal main in the street that is also lead. Historically, only trace elements of lead are measurable in residential domestic water systems.

Threaded Brass
Threaded brass is uncommon, however, you may still see it in homes built before 1940. The same things that affect copper tend to impact brass.


Shut Off Valves

  • Water Heater – The shutoff valve should be on the supply or cold side. Typically, there is no shut off valve on the “out” or “hot” side.
  • Hydronic Boiler – Find the shut off valve at the water supply to the boiler, and if the unit supplies domestic hot water, there will also be a shut off to the domestic water coil.

Hose Bibs
All hose bibs should be checked to insure that water flows from them. There are two types of hose bibs:

  • Anti-frost – The anti-frost hose bib is a unit that goes through the wall, with the seat of the valve located in the heated portion of the house (approximately 8 to 14 inches in from the exterior). This usually prevents the faucet from freezing and rupturing. It is necessary to remove garden hoses from all hose bibs in cold months, to prevent freezing and damage to the hose.
  • Sill cock – This is a standard hose bibb. The air bleeder at the valve should be opened in colder months, to allow the water to drain out.

Waste Water Disposal

Municipal waste systems are designed and controlled by the governing municipality. The users pay a fee for usage; typically the fee is based on the amount of water the occupants of the home or building use.

Types of unauthorized systems

  • Dumping raw or untreated sewage into a body of water, such as a pond, river, lake, stream, etc.
  • Illegal discharge of graywater to the exterior (i.e. ground, ravine, ditch, etc.); dumping ground water from a sump pump or air conditioning condensate into a sewage line. Note: There are acceptable gray water drainage systems. Check with local authorities.
  • Waste water is sometimes routed from the laundry into the sump pit and then discharged by the sump pump to the exterior.

Main Clean Out

The main clean out is frequently located at the wall or the slab close to where the sewage line exits the property (i.e. if the sewer line is in the street, the cleanout will probably be located on the wall of the house that is closest to the street). The main waste clean out should be located at the base of the main waste discharge line. This line is typically 3-4 inches in diameter. Occasionally, a toilet may be the best access to the sewer line and may have to be removed, if it is located in the vicinity of the sewage line as it exits the property. This is in lieu of a cleanout.

Drain Line Materials

PVC – Easy to install and less expensive to buy. Should have a long dependable life. Caustic chemicals will dissolve or damage the plastic.

Galvanized Steel – Life expectancy is 50 to 75 years. It does not oxidize as fast as galvanized steel water supply lines.

Cast iron (picture to right) – Life expectancy is typically 60 to 100 years. Cast iron drain piping that fails sooner may have been installed with too much slope. Vertical piping may occasionally break from stresses and or inadequate support. Check cast iron piping at the base of the vertical sections and special attention the horizontal piping, approx. 8’ to 20’ past the vertical drop.

Copper – A quality system used mostly in the 1950s and 1960s. It was common to use copper drains for sinks and tubs, etc. into the 1990s. However, PVC is clearly the material of choice in modern construction.

Lead – Mostly found in older houses, mainly for traps under water closets, sinks, tubs and showers.

Orangeburg or Bermico – Manufactured during the Korean War years, it is a paper tape type pipe impregnated with tar. Its life expectancy is typically 30 to 60 years. In older neighborhoods, where Orangeburg pipe had been installed, it has mostly been replaced or abandoned. This pipe is used on the exterior and is susceptible to damage by tree roots. It also had a tendency to collapse with age.

Acrylonitrile-butadiene-styrene (ABS) – During the mid 1970s, Centaur and Phoenix Manufacturing, Inc. began to blend a variety of plastic resins and substances that were not virgin. If you find pipe that is marked “Centaur” or “Phoenix,” it is likely that the pipe is defective. Evaluate the degree of deterioration that may be present. The picture to the right is a combination of ABS and PVC piping.

Vents and Traps


Venting is necessary to provide air to displace the water that is moving down and through the drainage system.

Plumbing vents should be at least 6 inches above the roofline, on the high side of the penetration. Vents must be at least 10 feet from windows. “In the wall” or “under-the-counter” vents are normally not permitted and must be authorized by the local code. A cooking island in a kitchen, that has a sink, very often has a vent of this type under the counter. Vents should be within 42 inches of the fixture being vented.


Traps prevent odorous sewage gases from entering the house through the sink and tub drains. There are two basic types of traps:

  • “P” traps discharge is horizontal rather than vertical. The liquid seal is dependable.
  • The full “S” trap or 3/4 “S” trap should not be used in plumbing installations.  These traps are almost impossible to vent properly. The 3/4 “S’ trap forms a perfect siphon. The problem with “S” traps is that the waste water may siphon out, causing the trap to lose its liquid seal. Every plumbing fixture, such as sinks, tubs and showers, should have a proper trap. Toilet traps are built into the bowl of the toilet. If a sink, etc. does not have a trap, trace the drain for other inequities that may be present (i.e. draining into a sump pump, a dry well or to the exterior surface). In older construction, there are thousands of “S” traps in use. Older building codes did not address this issue. In many cases it will be very difficult to change an “S” trap to a “P” trap.

Cross Connections

A cross-connection is present when there is a possibility that the potable drinking water could mix with the non-potable wastewater. The most logical occurrence is when the pressure in the supply system changes or is turned off, and non-potable water is drawn into the supply system. Examples:

  • When the faucet outlet or spout is below the rim or upper-most level of a sink or tub.A spout may be very close to the rim, and if someone adds or raises the level of the rim with some typ of tile on the counter top, you would have a cross-connection.
  • A sink or bathtub with a sprayer or shower head with a hose that is below the rim could allow contaminated water to be drawn into the supply piping if the pressure goes off or is turned off.
  • The toilet supply may become detached and fall below the water level or drain overflow tube.
  • The water in the tank may be drawn into the supply line if the pressure goes off.
  • A garden hose could end up in a number of undesirable areas that could draw contaminated materials into the hose or supply system.
  • Contaminated water could drain into a dishwasher if the sink drain backs up. This may not affect the clean dishes, however, it is a dangerous condition that could have significant ramifications.
    Conditions have to be just right for these problems to occur, but they are possible. Stagnant, contaminated fixtures can impact the good water coming through a compromised fixture for months or longer if the conditions allow the contaminants to flourish, such as in the bottom of a dishwasher.

Pipe Installations

Waste Line Slope
All sewage or waste lines should have a downward slope of 1/8 to 1/4 inch per foot for their entire run. There should be no low spots, sags or slopes of more than 1/4 inch per foot. Low spots or sags tend to allow sewage to accumulate and create vulnerabilities for leaking.

Water supply and waste lines should be supported every 4 feet. This support can be in the form of brackets, wire hangers, or in some cases, the pipes run through structural members such as joists. The brackets should be the same or a material compatible with the piping. If this is not possible, there should be a separation between the dissimilar materials.

Shower and Tub Wall Surfaces

Ceramic Tile

Wet-bed – There are two basic methods of setting ceramic tile. Wet-bed systems, mostly in older properties, are made up of a cement base or ground coat over wire lath. A second cement coat will receive the tiles. After the tiles are set and allowed to dry, the tiles can be grouted. Wet-bed systems are superior to mastic systems. About half of the showers with lead pan bases tend to fail in the 45 to 55-year range. You may wish to cover the drain with a wash cloth or small towel, assuming there is no drain plug, fill the base of the shower with 3 to 4 inches of water, turn the water off and remove the wash cloth or towel. Wait 5 minutes and check the ceiling below. Tap and gently press on the tiles around the perimeter of the bottom 3 courses of a shower stall, around the faucets of a tub or shower and at the sidewall of a tub, closer to the front to look for loose tiles, which may indicate deteriorated or water damaged substrate.

Mastic – Modern tile is placed directly onto a green board, which is drywall with a small amount of asphalt in the paper to make it water-resistant. The tiles are then set in a mastic or adhesive designed for this application. Grouting of the tile can be done the next day. Tile systems set over water-resistant drywall or sheetrock has a typical life expectancy of 10 to 14 years in a shower and 12 to 16 years in a tub/shower situation. Check the areas around the bottom of the shower and at the faucets and wall closest to the faucets in the tub/shower situation. A better mastic system is installed with a waterproof substrate, such as wonder board, which is a cementious board, instead of the water-resistant gypsum drywall board.

Plastic Tile

Plastic tile is a low-end material and is usually not installed in modern construction.

Fiberglass Tub/Shower

Fiberglass tubs and showers are less expensive and relatively common in new construction. The newer units are superior to older units because older units are thinner, and tend to crack and discolor. The modern fiberglass is stable and the bottoms are thicker, supported better and do not crack like some of the older mid-1970s tub units. After you checked the ceiling below, the best way to check for problems is to stand in the unit in about the same position you would if you were taking a shower. From this position, look for cracks to the outsides of your feet. They may only leak with someone standing in the tub. This is especially common with the 20 to 25 year-old units.


Hardboard, such as Marilite, is an inexpensive compressed board with a glossy finish. The life expectancy is 5 to 7 years in a tub/shower that is used daily. Water has a tendency to leak into the edges of this material. This moisture is absorbed into the hardboard and the finish separates.



Many fixtures, such as toilets and sinks, have the date of manufacture stamped on them. This is one way to help determine the age of the property, assuming there have been no renovations. Most common defects:

  • Loose at base, with a possibility of deteriorated wood. This defect is obvious by gently rocking the toilet and observing the ceiling below.
  • The flush assemblies should be checked for leaking and their ability to fill the tank properly.
  • Look for water behind the toilets that may be coming from the tank or the seal at the base of the bowl.
  • Cracks in the tank or bowl, especially at the closet bolts. Broken tank lids.

Water Heaters

Shut-off valves – If there is only one shut off valve, it should be on the cold/inside.

Temperature/Pressure Relief Valve (TPR valve) – All water heaters should have a TPR valve to prevent a possible explosion. Do not test the pressure relief valve, because it may not reseat, causing the pressure relief valve to seep. Water heaters have a drain at the bottom. The purpose of this is to drain the tank when/if necessary or to remove any debris buildup on the bottom of the tank. Some people recommend draining any debris from the sacrificial anode that ends up at the bottom of the tank, however, very few people drain their water heaters. Gas and oil water heaters need an exhaust system. The exhaust system typically shares the chimney with the heating plant. The water heater, or smaller appliance, should enter the chimney flue above the larger vent connector for the furnace or boiler. TPRs should have a pipe extension to within 6 inches of the floor. These direct any discharging hot water to the floor and away from people who may be in the area.

Garage Installation – Water heaters installed in the garage should have the firebox 18 inches above the slab. A water heater in a garage also needs a security post in front of it to prevent it from being hit by an automobile. California requires earthquake strapping and flexible fuel and water piping.

Scalding Water – Water heaters should be set at 125° Fahrenheit or less. Temperatures set higher may cause scalding of children or people with limited mobility. First degree burns or reddening of the skin can occur in 2 seconds at 150 degrees; in 6 seconds at 140 degrees; and in 30 seconds at 130 degrees.

Age – The age of the water heater can be determined from the serial number, but you will need the manufacturer’s code. An option would be to check the first 2 numbers on most of the metal tags on the TPR valve for the year that the TPR valve was manufactured. This is probably the same year that the water heater was manufactured.

Life Expectancy – The life expectancy of most water heaters is 10 to 15 years. Electric units tend to last a little longer than gas or oil-fired units. Summer/winter hookup is a domestic water coil that is immersed and integrated with the boiler of hydronic or steam boilers. Manufacturer’s warranties are typically 5 years, 7 years and 10 years. The difference in warranty time is generally due to the sacrificial anode that tends to deteriorate before and in lieu of the lining seams. The longer the anode, the longer the warranty and the more the water heater will cost.

Laundry Tubs

Cement – Cement laundry tubs were common in the 1920s, 30s and 40s. They were dependable for about 50 years. They have a tendency to crack at the base, near the drain. Look for seepage and or some type of sealant on the bottom of the tub, inside and outside.

Fiberglass – Fiberglass laundry tubs should have long lives, but check to see that they are secured properly.

Clothes Washers – Clothes washers can either discharge into a laundry tub or a standpipe. In either case, this should have a “trap.”

Clothes Dryers – Gas dryers should vent to the exterior to discharge moisture vapors and the potential for carbon monoxide accumulation.

Shower Stalls

Older units may have wet-bed ceramic tile with a lead pan drain. A modern shower stall will usually have a fiberglass base. The ceramic tile is typically installed over a water-resistant drywall or sheetrock. Better installations will use a waterproof cementious wallboard in lieu of water-resistant drywall to install the ceramic tile. The life expectancy of the water resistant installation is 8 to 12 years in a shower stall that is used daily. The waterproof installations should last 40 to 60 years, mostly dependent upon usage and workmanship. Modern fiberglass shower stalls and tub enclosures are a reasonable option for dependability and economy.

Whirlpool Tub

A whirlpool tub is a tub with a motor utilized to circulate the water. Hot tubs are much larger, and are normally located outside. Whirlpools are sometimes called Jacuzzis; however, Jacuzzi is the most prominent brand name. Fill the whirlpool to about 1 inch above the jets; turn on the unit to determine proper operation. Check the ceiling below the whirlpool and the adjacent plumbing fixtures.


Designed for cleanliness and hygiene of localized parts of the body. Equipped with valves for hot and cold water, the inside walls of the bowl are washed the same way as a standard toilet. The bidet is not designed or intended to carry away solid human waste.

Sinks, Bathtubs and Fixtures

Sinks and bathtubs, etc. should be inspected for cracks and/or surface deterioration. There are a number of materials that are used to manufacture these appliances, and there are pros and cons to all of them. For example, steel is strong, but the porcelain chips easily. Synthetic sinks look good, but their surface is somewhat fragile and cracking is common at and around the drain. Cast iron is dependable, however, the porcelain will still chip. Corian will scratch, but it can be sanded smooth. Corian has a minor tendency for cracking at the drain.

Fiberglass tub surrounds are durable, however, it is not unusual for them to come loose due to the preparation of the walls, the application of the wall material and/or the adhesive. In many cases, these surrounds are installed over the failed tile and deteriorated wall materials behind the tile. To assess this condition, press on the walls in the area of the faucets and along the side wall closer to the front of the tub or towards the end where the faucets are located.

Marilite wall covering is a cellulose-based composition hardboard panel with a thin plastic finish. It makes an acceptable wall covering, however, it is not a dependable waterproof surface for tub/shower areas. Typically, the life expectancy of this type of material, assuming daily shower usage, is approximately 5 to 7 years. The first areas that fail are along the bottom, where the surface is scratched, or at loose joints.

Bathroom and Powder Room Ventilators/Exhaust Fans

Every bathroom or powder room should have a ventilator or exhaust fan, unless it has a functioning window. Bathroom ventilators and exhaust fans should terminate to the exterior (i.e. through the wall, roof, or at the ventilator). Terminating a ventilator in the attic is a defect. If the ventilation is adequate and/or there is little or no insulation, it is unlikely that there will be condensation problems due to the ventilator terminating in the attic.

Water heaters or other combustible fuel appliances should not be installed in bedrooms or bathrooms. The concerns are related to the possibility of carbon monoxide gas backing into the space from potential chimney venting/exhaust problems.

Gas Piping

Gas piping in residential applications is typically black steel. Galvanized steel can be used, however, it is more expensive and not necessary. Seamless steel, copper and aluminum alloy tubing are allowed with gases are not corrosive to the piping materials.

Aluminum alloy tubing is not to be used on the exterior or underground. Corrugated stainless steel tubing should comply with performance requirements of Standard Fuel Piping Systems.

Plastic pipe, tubing and fittings are for underground use only and should conform to Standard Specification for Thermoplastic Gas Pressure Pipe and Fittings. Piping should be marked “gas” and “ASTM D 2513.”

Interior gas piping should not be installed through a circulating air duct, clothes chute or gas vent, ventilating duct, and dumbwaiter or elevator shaft.

The above ground portion of the gas piping system, upstream from the equipment shutoff should be bonded to a grounding electrode. The gas piping is not to be used as a grounding electrode.

Home inspectors do not check gas pressure, however, testing should not be more than 1 ½ times the maximum working pressure and not less than 3 psig for 10 minutes.

Unvented room heaters are not to be installed in bathrooms or bedrooms. But if the unit is smaller than 6000 BTUs and has an oxygen depletion safety valve, it can be installed in a bathroom. Equipment that does not require venting should be listed and in some cases marked.

Common Defects

  • Leaks in waste or supply lines or at fixtures.
  • Orangeburg pipe – problems are age or tree root-related.
  • Disposal of gray water into an unapproved septic system.
  • Deteriorated piping and traps, etc.
  • Improper slopes, improper toilet valves, improperly supported pipes.
  • Older galvanized pipe. Look for rust warts and or restricted flow.
  • Life pumps, lift stations. Check operation; limited access.
  • Improper venting
  • Not through roof
  • Too close to windows or ventilators
  • “S”Traps. Not enforced.
  • Water heaters – Non existent or improper temperature/pressure relief valve extensions.
  • Loose, deteriorated wall materials at bath/shower areas. (i.e. tile)
  • Improper vents.
  • Residual chlorine in well water. May indicate ongoing bacteria problem.
  • Lead in water – screening test.
  • Polybutylene piping. Look for leaks and crimped joints.
  • Back drafting of water heaters or furnaces.
  • Water too hot.
  • Loose toilets.
  • Functional flow.
  • Waste systems.