A Thorough Guide: From Basic Knowledge of Plumbing Systems to the Service Life of Equipment

Plumbing systems are essential facilities that safely supply water within buildings and properly discharge water after use. They are indispensable for all types of buildings, including houses, apartment buildings, and commercial buildings, and support our comfortable daily lives.

However, surprisingly few people may have an accurate understanding of how plumbing systems work, the service life of equipment, and the mechanisms of the equipment. If plumbing systems do not function properly, this may not only interfere with water service but also lead to deterioration of the sanitary environment and damage to the building.

This article explains, in an easy-to-understand way, everything from the basic knowledge of plumbing systems to equipment service life, the importance of maintenance, and key points for renovation work. By gaining accurate knowledge of plumbing systems, you should be able to prevent problems and plan maintenance more effectively. Please read through to the end.

 

What Are Plumbing Systems?

Plumbing systems can be broadly divided into two categories: water supply systems and drainage systems. A water supply system supplies water from the public water supply to a building, while a drainage system discharges sewage and miscellaneous wastewater to the sewer system. Water supply systems and drainage systems work closely together and contribute to a comfortable living environment.

Through periodic inspections and appropriate maintenance, these systems can maintain stable functions over the long term. The following sections take a closer look at drainage systems.

 

Drainage Systems

Drainage systems are indispensable for effectively discharging sewage and rainwater from inside and around buildings, thereby maintaining a hygienic and comfortable living environment. Proper installation and management of drainage systems have a major impact on the durability of a building and the quality of the living environment.

 

Drainage Pipes

Drainage pipes safely discharge sewage, rainwater, miscellaneous wastewater, and other wastewater generated in homes and buildings to the outside of the building. When design and material selection are appropriate, drainage problems are reduced, and sanitation and building durability are improved. Drainage pipes include several types, such as sewage pipes, miscellaneous drainage pipes, and rainwater pipes, each with a different purpose.

Drain traps installed in many drainage pipes are designed to prevent foul odors and pests from entering indoor spaces. The layout of drainage pipes and the quality of installation work are also key points in maintaining a comfortable living space. The following sections explain the types of drainage pipes.

 

Sewage Pipes

A sewage pipe is a drainage pipe that hygienically and reliably carries sewage, such as human waste discharged from toilets, to the outside of the building. Among the pipes handled in plumbing system work, sewage pipes require particularly careful sanitary consideration. Corrosion-resistant materials are used for sewage pipes, including PVC (rigid polyvinyl chloride pipe), fire-resistant double-layer pipe, cast iron pipe (CIP), and SGP piping.

When laying these pipes, it is essential to secure sufficient gradient and airtightness. Because leakage or damage can lead to foul odors and sanitary problems, periodic inspections and maintenance are also emphasized. Proper installation and management of sewage pipes are fundamental elements for maintaining a comfortable and clean lifestyle.

 

Rainwater Pipes

Rainwater pipes collect and safely discharge rainwater flowing from roofs, balconies, verandas, exterior walls, and other areas to the outside of the building. Rainwater management helps reduce risks such as flooding around the building and ground subsidence. Materials with excellent weather and water resistance, such as vinyl chloride pipe and concrete, are generally used for rainwater pipes.

When installing rainwater pipes, it is important to select the gradient, outlet position, and pipe diameter appropriately. Proper planning and installation can prevent drainage failure and damage before they occur. Rainwater pipes are indispensable for maintaining a comfortable environment and extending the service life of buildings.

 

Miscellaneous Drainage Pipes

Miscellaneous drainage pipes carry wastewater from kitchens, washrooms, bathrooms, and washing machines. Separate from toilet drainage, they efficiently discharge domestic wastewater and help maintain the sanitary environment of the building. Miscellaneous drainage pipes are managed together with sewage pipes and rainwater pipes, contributing to the efficiency of the overall drainage system.

Because the precision of design and installation can prevent problems such as clogging and backflow, proper construction and periodic inspections are necessary. Appropriate management of miscellaneous drainage pipes helps maintain a comfortable living environment.

 

Vent Pipes

Vent pipes adjust air pressure inside drainage pipes appropriately and help ensure the smooth flow of drainage. Vent pipes are necessary to prevent pressure fluctuations inside drainage pipes. Without vent pipes, negative pressure occurs inside the piping during drainage, which can break the water seal in drain traps. As a result, foul odors from sewers and pests may enter the building.

The venting method for vent pipes is selected according to the size of the building. In detached houses, the stack venting method is often used, while loop venting is commonly adopted in office buildings. Other methods include individual venting and special fitting drainage systems. Selecting the appropriate method improves the performance of the entire drainage system.

 

Drainage Tanks and Drainage Pumps

Drainage pumps are indispensable equipment in buildings where natural gravity drainage is difficult. In buildings with basement or semi-basement structures, wastewater cannot flow naturally into sewer pipes, so drainage pumps are used to pump and discharge it. Drainage tanks are installed according to the drainage volume and intended use, and are generally used in combination with drainage pumps.

One type is a sewage tank that stores wastewater from toilets and similar sources; another is a miscellaneous drainage tank that stores domestic wastewater from kitchens, washstands, and other fixtures.

Depending on the surrounding environment, other tanks may also be installed, such as spring water tanks for handling groundwater and spring water, and rainwater tanks for temporarily storing rainwater.

These drainage tanks must be properly separated and installed according to their respective purposes, and design and installation must be carried out in accordance with Japan’s Building Standard Law and other related Japanese laws and regulations.

Drainage pumps generally operate automatically through water-level control or timer control, and are designed to start when the water level inside the drainage tank reaches a certain point. Because wastewater left stagnant for a long time can produce foul odors and sanitary problems due to decomposition, the system is designed so that drainage takes place within several hours.

In addition, under Japan’s Act for Maintenance of Sanitation in Buildings, commonly referred to in Japan as the Building Management Law, drainage tanks in specified buildings are required to be cleaned at least once every six months (at least twice a year). Depending on the scale of the equipment and the conditions of use, cleaning about three times a year may also be recommended from the perspectives of sanitation and equipment preservation.

If cleaning and inspections are neglected, foul odors, clogged drainage pipes, and pump failures may occur. For this reason, periodic maintenance by a specialized contractor is important.

 

Importance of Plumbing Systems

Plumbing systems play the important role of protecting water, which is essential for human beings to live healthy lives.

 

Maintaining a Comfortable Living Environment

Plumbing systems are essential for smoothly supplying and discharging water in the home. A clean water supply and efficient drainage system make daily life more comfortable.

 

Ensuring Sanitation

Appropriate plumbing systems are directly linked to maintaining a hygienic environment. Proper treatment of drainage prevents the growth of bacteria and viruses and reduces health risks. A clean water supply also contributes to the prevention of infectious diseases.

 

Improving Building Durability

When plumbing systems are properly installed and maintained, the durability of the building itself improves. By minimizing the risks of leaks and water damage, damage to the structural parts of the building can be prevented, allowing residents and users to live with peace of mind over the long term.

 

Improving Energy Efficiency

Efficient plumbing systems help reduce energy consumption. To send water to upper floors or distant locations, pressure must be applied using pumps, which consumes electricity. Inefficient piping layouts, excessive pumping heights, and the use of old pump units therefore lead to wasted energy consumption. Poor design or operating efficiency of drainage tanks can also create unnecessary electricity and maintenance costs.

 

Improving Disaster Response Capability

Stable plumbing systems also play an important role during natural disasters such as earthquakes and typhoons. Rapid water supply and drainage functions can support the basic infrastructure of daily life during disasters.

 

Service Life of Plumbing System Equipment

Below, let us look at the service life of plumbing systems and other equipment, the factors that affect service life, and measures for extending service life.

 

Service Life of Water Supply Systems

The service life of water supply pipes varies greatly depending on the material. In general, stainless steel pipes and polyethylene pipes (PEX pipes) are said to last about 30 years, rigid polyvinyl chloride pipes (VP pipes) about 20 to 25 years, impact-resistant polyvinyl chloride pipes (HIVP pipes) about 30 years, and polybutene pipes (PB pipes) about 30 to 40 years.

When the service life is exceeded, defects such as water leaks, pipe bursts, red water (rust-colored water), and reduced flow may occur. In some cases, large-scale repairs may be needed by the time the issue is noticed.

 

Service Life of Drainage Systems

The service life of drainage pipes used in drainage systems also depends on the material. Cast iron pipes (including SML pipes) are said to last 30 to 50 years, vinyl chloride pipes (VP pipes) about 20 to 30 years, and stainless steel drainage pipes about 30 to 40 years. The general service life of drainage pumps is around 10 years.

 

Service Life of Water Storage Tanks

The service life of water receiving tanks and elevated water tanks varies depending on the material and installation environment. In general, stainless steel water storage tanks have a service life of about 25 to 30 years, FRP (fiber-reinforced plastic) tanks about 15 to 20 years, and reinforced concrete (RC) tanks about 30 to 40 years, although the service life of the internal waterproofing treatment must be considered separately.

Under Japan's Waterworks Law, water storage tanks used to supply drinking water to buildings with an effective capacity exceeding 10 m3 (Building Water Tank Systems) are required to undergo periodic cleaning and water quality testing at least once a year. In addition, under ordinances of individual local governments in Japan, self-inspection results must also be promptly reported to the public health center.

 

Service Life of Water Supply Pumps

Water supply pumps include lifting pumps, booster pumps, and pressure pumps, and each has a different service life. Lifting pumps generally have a service life of about 10 to 15 years, booster pumps about 10 years, and pressure pumps vary depending on frequency of use and the operating environment.

 

Service Life of Hot Water Supply Equipment

The service life of water heaters varies by type. Gas water heaters generally last about 10 years, household electric water heaters have a statutory useful life under Japanese tax rules of 6 years, and oil-fired water heaters generally last about 20 years.

 

Factors Affecting Service Life

The actual service life is also affected by the installation environment, construction quality, water quality, pipe gradient, and other factors. Additional factors include the following:

• Quality of the materials used
• Implementation of periodic maintenance
• Overloading or inappropriate use
• Environmental changes, such as temperature and humidity

 

Measures for Extending Service Life

• Periodic inspections and maintenance
• Compliance with appropriate methods of use
• Implementation of corrosion prevention measures and waterproofing treatment
• Early detection of abnormalities and prompt repairs
• Selection of high-quality materials

 

Laws and Regulations in Japan Concerning Service Life

In Japan, laws such as Japan’s Building Standard Law and Japan’s Waterworks Law establish requirements regarding the installation and maintenance of plumbing systems. Based on these Japanese laws and regulations, appropriate equipment selection and maintenance are required. Non-compliance may result in legal action or fines under Japanese law, making legal compliance important.

 

Methods of Plumbing System Work

Plumbing system work is important work that involves the installation and repair of water supply and drainage systems inside and outside buildings.

Type of Work	Main Work Details	Primary Materials Used
In-building work	Piping installation, equipment installation, inspections and adjustments	PVC pipes, copper pipes, sealing materials, water heaters, etc.
Outdoor work	Connection of main piping, installation of rainwater drainage systems, installation of pump equipment	PE pipes, pumps, rain gutters, drainage ditches, etc.

 

In-building Work

In-building work involves the installation of plumbing systems and piping work inside the building.

• Piping design and layout
• Piping work
• Equipment installation
• Inspections and adjustments

 

Outdoor Work

Outdoor work involves the installation of water supply and drainage systems outside the building.

• Connection of main piping
• Installation of rainwater drainage systems
• Installation of pump equipment
• Repair and finishing of exterior walls

At AMCON, we can handle all types of plumbing system work, including the installation of new equipment and renovation work associated with aging equipment. By comprehensively assessing the current condition of the equipment based on equipment status, renovation work history, periodic inspection records, and other information, we propose the most suitable renovation work.

 

Summary | For Plumbing System Maintenance, Inspections, and Work, Contact AMCON!

Plumbing systems refer to the overall systems that properly supply and drain water inside buildings, and can be broadly divided into two categories: water supply systems and drainage systems. Drainage systems, including sewage pipes, rainwater pipes, miscellaneous drainage pipes, vent pipes, drainage tanks, and drainage pumps, are essential for maintaining a hygienic and comfortable living environment.

The service life of equipment varies greatly depending on the material and type, including water supply pipes, drainage pipes, water storage tanks, pumps, and water heaters. The actual life span also varies depending on the installation environment, construction quality, and maintenance status. Periodic inspections and maintenance are also key to extending service life.

It is also possible to reduce electricity consumption and achieve energy savings by replacing old pump units with new inverter-type pump units. For plumbing system work, please feel free to consult us with confidence, as we have extensive specialized knowledge and experience.