Plumbing Systems

Evaluation of all plumbing systems and their components in accordance with industry standards, which includes testing for pressure and functional flow. Plumbing systems have common components but they are not uniform. In addition to fixtures, components typically consist of gas pipes, potable water pipes, drain and vent pipes, shut-off valves, pressure regulators, and pressure relief valves that is not tested or dismantled.

Gas Piping

A visual inspection of the gas service systems and components did not reveal any major defects or leaks at the time of the inspection unless I noted it in the Plumbing section of your home inspection report.

Supply Piping

The best and most dependable water supply pipes are copper, because they are not subject to the build-up of minerals that bond to the inside of galvanized pipes and gradually reduce their inner diameter and restrict the volume of water. A water softener will remove most of these minerals, but not once they are bonded within the pipes, for which there would be no remedy other than to re-pipe. The water pressure within the pipes is commonly confused with water volume, but whereas high water volume is good, high water pressure is not. In fact, whenever the street pressure exceeds eighty pounds per square inch, a regulator is recommended, which typically comes factory preset between forty-five and sixty five pounds per inch. However, regardless of the pressure, leaks will occur in any system and particularly in one with older galvanized pipes and commonly when the regulator fails and high pressure begins to stress the washers and diaphragms within the various components.

Hot and Cold Water Main Lines: The hot and cold water main lines are usually hung from the basement ceiling and are attached to the water meter and hot-water tank on one side and the fixture supply risers on the other. These pipes should be installed in a neat manner and should be supported by pipe hangers or straps of sufficient strength and number to prevent sagging. Hot and cold water lines should be approximately 6 inches apart unless the hot water line is insulated. This is to insure that the cold water line does not pick up heat from the hot water line. The supply mains should have a drain valve or stop and waste valve in order to remove water from the system for repairs. These valves should be on the low end of the line or on the end of each fixture riser.

The fixture risers start at the basement main and rise vertically to the fixtures on the upper floors. In a one-family dwelling, riser branches will usually proceed from the main riser to each fixture grouping. In any event the fixture risers should not depend on the branch risers for support but should be supported with a pipe bracket. Each fixture is then connected to the branch riser by a separate line. The last fixture on a line is usually connected directly to the branch riser.

Waste Pipes

Attempts to evaluate drain pipes by flushing every drain that has an active fixture while observing its draw and watching for blockages or slow drains, but this is not a conclusive test and only a video-scan of the main line would confirm its actual condition. However, you can be sure that blockages will occur, usually relative in severity to the age of the system, and will range from minor clogs in the branch lines, or at the traps beneath sinks, tubs and showers to major blockages in the main line. The minor clogs are easily cleared, either by chemical means or by removing and cleaning out the traps. However, if tree roots grow into the main drain that connects the house to the public sewer, repairs could become expensive and might include replacing the entire main line.

For these reasons, it is recommend that you ask the sellers if they have ever experienced any drainage problems, or you may wish to have the main waste line video-scanned before the close of escrow. Failing this, you should obtain an insurance policy that covers blockages and damage to the main line. However, most policies only cover plumbing repairs within the house or the cost of rooter service, which are usually relatively inexpensive.

The seal in a plumbing trap may be lost due to siphonage (direct and indirect or momentum), back pressure, evaporation, capillary attraction, or wind effect. The first two named are probably the most common causes of loss. If a waste pipe is placed vertically after the fixture trap, as in an "S" trap, the waste water continues to flow after the fixture is emptied and clears the trap. This is caused by the pressure of air on the fixture water's being greater than the pressure of air in the waste pipe. The action of the water discharging into the waste pipe removes the air from that pipe and thereby causes a negative pressure in the waste line. In the case of indirect or momentum siphonage, the flow of water past the entrance to a fixture drain in the waste pipe removes air from the fixture drain. This reduces the air pressure in the fixture drain, and the entire assembly acts as an aspirator such as the physician uses to spray an infected throat.  

Back pressure

The flow of water in a soil pipe varies according to the fixtures being used. A lavatory gives a small flow and a water closet a large flow. Small flows tend to cling to the sides of the pipe, but large ones form a slug of waste as they drop. As this slug of water falls down the pipe the air in front of it becomes pressurized. As the pressure builds it seeks an escape point. This point is either a vent or a fixture outlet. If the vent is plugged or there is no vent, the only escape for this air is the fixture outlet. The air pressure forces the trap seal up the pipe into the fixture. If the pressure is great enough the seal is blown out of the fixture entirely. Figures 6-17 and 6-18 illustrate this type of problem.

Vent sizing

Vent pipe installation is similar to that of soil and waste pipe. The same fixture unit criteria are used. Vent pipes of less than 11 D4 inches in diameter should not be used. Vents smaller than this diameter tend to clog and do not perform their function.

Corrosion

Corrosion build-up is often present on pipes and valves in sink cabinets, at toilets, and at the water heater. Although corrosion is common, it can indicate leaks, static electric charges on metal pipes, dissimilar material connections (typically between two different metals), and/or chemical storage nearby, particularly in sink cabinets; other causes also are possible. Such corrosion build-up in all visible areas might not be noted in your report because it is so common. However, a significant build-up of corrosion could be concealing an active leak, although the leak in such cases usually is minor. Remember, though, that neglecting a minor leak can result in a major leak. At that point, you could have major water damage and significant mold or mildew.

What might have been considered light corrosion on the day of the inspection could have been the start of a problem and a more serious build-up of corrosion could be present by the time escrow closes. Any pipes that have corrosion should be cleaned and inspected. Check the pipes and valves in the sink cabinets before storing items in those cabinets. Regular homeowner monitoring and maintenance is easy to do.

Shower Pans

Shower Pans are visually checked for leakage, but leaks often do not show except when the shower is in actual use. Determining whether shower pans, tub/shower surrounds are water tight is beyond the scope of my inspection. It is very important to maintain all grouting and caulking in all bath areas.