Worth to know
In some systems the drain is for discharge of waste fluids, such as the drain in a sink in which the water is drained when it is no longer needed.
In the United Kingdom, plumbers refer to waste water as 'bad water'. This is under the premise that the water they are moving from one area to another via the use of a drain is not needed and can be removed from the area, like a 'bad apple' being removed from a fruit bowl.
In other systems, such as fountains or swimming pools where waste fluid is recirculated, the drain is the input to the recirculating pumping machine.
In the last case, there is an obvious safety issue, because many people do not expect to encounter more than the head of water above the drain when touching a drain. For example, in a recent case, a lifeguard went to the bottom of a pool to retrieve something and his hand got stuck because of the extra pressure from the pump. When there is a recirculating pump, the risk of suction consists of the head of water, plus the suction of the pump (up to a maximum of 1 atmosphere).
Repair of small hydraulic failure
Malfunctions related to the plumbing is a real nightmare for the residents of the building. There are often such failures, which for a long time to hinder the normal functioning and cause many other problems, but some of them are too small and can be quickly repaired. It is important, however, that even the smallest failure to call the appropriate professionals, because even if something on the surface it seems to us trivial, inadequately repaired, can result in a much higher failure and pretty large problems. Repair small defects do not pay much, and good specialist will deal with it quickly and professionally. It is so much simpler, cheaper and better solution than self-repair.
About plastic material
Plastic pipe is in wide use for domestic water supply and drain-waste-vent (DWV) pipe. Principal types include: Polyvinyl chloride (PVC) was produced experimentally in the 19th century but did not become practical to manufacture until 1926, when Waldo Semon of BF Goodrich Co. developed a method to plasticize PVC, making it easier to process. PVC pipe began to be manufactured in the 1940s and was in wide use for Drain-Waste-Vent piping during the reconstruction of Germany and Japan following WWII. In the 1950s, plastics manufacturers in Western Europe and Japan began producing acrylonitrile butadiene styrene (ABS) pipe. The method for producing cross-linked polyethylene (PEX) was also developed in the 1950s. Plastic supply pipes have become increasingly common, with a variety of materials and fittings employed.
PVC/CPVC ? rigid plastic pipes similar to PVC drain pipes but with thicker walls to deal with municipal water pressure, introduced around 1970. PVC stands for polyvinyl chloride, and it?s become a common replacement for metal piping. PVC should be used only for cold water, or for venting. CPVC can be used for hot and cold potable water supply. Connections are made with primers and solvent cements as required by code.12
PP ? The material is used primarily in housewares, food packaging, and clinical equipment,13 but since the early 1970s has seen increasing use worldwide for both domestic hot and cold water. PP pipes are heat fused, being unsuitable for the use of glues, solvents, or mechanical fittings. PP pipe is often used in green building projects.1415
PBT ? flexible (usually gray or black) plastic pipe which is attached to barbed fittings and secured in place with a copper crimp ring. The primary manufacturer of PBT tubing and fittings was driven into bankruptcy by a class-action lawsuit over failures of this system.citation needed However, PB and PBT tubing has since returned to the market and codes, typically first for "exposed locations" such as risers.
PEX ? cross-linked polyethylene system with mechanically joined fittings employing barbs, and crimped steel or copper rings.
Polytanks ? plastic polyethylene cisterns, underground water tanks, above ground water tanks, are usually made of linear polyethylene suitable as a potable water storage tank, provided in white, black or green.
Aqua ? known as PEX-Al-PEX, for its PEX/aluminum sandwich, consisting of aluminum pipe sandwiched between layers of PEX, and connected with modified brass compression fittings. In 2005, a large number of these fittings were recalled.further explanation needed
Present-day water-supply systems use a network of high-pressure pumps, and pipes in buildings are now made of copper,16 brass, plastic (particularly cross-linked polyethylene called PEX, which is estimated to be used in 60% of single-family homes17), or other nontoxic material. Due to its toxicity, lead has not been used in modern water-supply piping since the 1930s in the United States,18 although lead was used in plumbing solder for drinking water until it was banned in 1986.18 Drain and vent lines are made of plastic, steel, cast-iron, or lead.1920