A plumbing system is the part of a plumbing system that carries potable (drinkable) water to plumbing fixtures, appliances, and devices. The term drainage system may be used interchangeably with the plumbing system.
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Plumbing pipes are usually made of copper, CPVC or PEX, galvanized steel or lead (known as “Pipeline”-grade) which was widely used up until World War II, but due to its toxicity has been banned in plumbing applications in most countries outside limited uses in continental Europe. Lead was also used for solder for much of history, but lead-tin alloy solder has largely been replaced by non-le alloys since the late 20th century. Drain plumbing pipes are almost always made of plastic (PVC, CPVC and ABS work well) and copper piping is sometimes used where none of these other options are available or will be exposed to soil or water.
Plumbing System Layout
The plumbing system should be laid out in a way that makes it easy to repair. Plumbing design addresses both the plumbing structure itself (the arrangement of pipe, valves, plumbing fixtures and so on) as well as the location of plumbing fixtures such as sinks, lavatories, showers, bathtubs and toilets within a building. The goal is to layout all plumbing fixtures as close together as possible so plumbing pipes do not need to run long distances horizontally or vertically unnecessarily. This helps save space and minimizes the pipe lengths which will reduce installation cost.
The plumbing structure should be of the best quality, since it is often exposed to harsh conditions (soil or subsoil, water, oxygen) and aggressive agents (chemical cleaners). Water-quality issues are also linked with plumbing system but can be managed if avoidable by choosing plumbing materials that are resistant to aggressive agents (e.g., chloride), avoiding plumbing structures that pass water under high pressure or containing water in areas where bacteria thrive. When plumbing structures do not work properly, they tend to snowball into more serious problems that require expensive professional help from plumbers. However, those costs may seem trivial compared with the cost of replacing a 20+ year old plumbing system entirely because it has been built improperly.
Plumbing System Materials
Plumbing materials must be chosen with plumbing system design parameters in mind, such as aging and heat resistance. Metal plumbing systems should be properly shielded from corrosion-inducing soil or subsoil; plumbing buried underground is often shielded by a bed of gravel and/or clay, which slows down the passage of aggressive agents like water and air (oxygen) to the metal plumbing materials. Plumbing pipes made of PVC pose no threat for metal plumbing material if they are run within walls or ceilings; however orientation might be important for drain lines to prevent moisture damage. In many countries certain toxic materials such as lead have been phased out from plumbing structures used inside buildings because all those toxic agents can potentially contaminate drinking water.
In addition to plumbing system design, plumbing systems are also designed for installation and maintenance ease. The pipe material chosen should be easy to bend into the desired location without excessive effort or use of special tools. Ideally it should not corrode under normal conditions or from contact with aggressive agents (e.g., water containing chlorine). The plumbing fixtures themselves should be durable enough to last throughout the lifetime of the building to avoid frequent replacements. Plumbing vents should be included in plumbing structures whenever possible to expel foul air as well as excess water that might back up into sinks or tubs due to gravitational effects, especially when plumbing fixtures are located on higher floors of a building instead of on ground level adjacent to sewer connections.
Plumbing supply lines must include a sufficient amount of accessible plumbing fixtures in order to complete plumbing system design. The locations of plumbing fixtures should be chosen before plumbing structures are designed since plumbing designers need to place plumbing pipes and other plumbing components such as water supply lines and venting precisely within a limited amount of space.
A building’s plumbing system is one part of the overall construction process. Plumbing supply lines must be installed before finishing work begins on interior spaces because plumbing pipes cannot be installed after many types of surfaces have been attached directly to studs or joists (e.g., drywall). Once those finishes have been applied, it becomes much more difficult for plumbers to gain access to plumbing pipes without causing extensive damage to them or the surface behind them. In addition, plumbing fixtures such as toilets and sinks must be installed after plumbing supply lines have been run to particular plumbing fixtures. Many plumbing codes also require that plumbing vents be installed before interior finishes are applied in order for the building to pass final inspection (called “drying-in”).
Plumbing System Maintanence
Finally, plumbing systems need to be maintained throughout a building’s life. Depending on local laws, this may include periodic inspections by certified plumbing contractors who use special instruments to determine whether sewer gases or other hazardous agents are infiltrating into occupied spaces through plumbing pipes (e.g., water vapor passing through crawlspace). Such inspections help ensure occupant health and safety by detecting plumbing leaks early enough for corrective actions to minimize the risk of property damage or personal injury resulting from sewer gas exposure.
Plumbing vents are pipes that are used to prevent plumbing system pressure from building up inside plumbing fixtures or plumbing supply lines. Plumbing vents are usually seen as small tubes on the exterior of buildings near plumbing fixtures, but they may be hidden behind walls in some cases. The plumbing vent ensures that excess water is expelled out of bathrooms and kitchens through a pipe and into the plumbing drainage system outside the house, and also prevents backflow to ensure positive flow.