Water Supply Systems

These systems deliver clean water into the building. In many buildings, a method is used in which water is first stored in receiving water tanks and elevated water tanks and then sent to each floor by pressure water supply pumps. In recent years, more apartment buildings have adopted direct booster water supply systems and direct pressure water supply systems, and the management points vary depending on the water supply method.

Drainage Systems

These systems discharge used water outside the building. They include drainpipes, manholes, grease traps (commonly used in food-service facilities and factories), and groundwater sumps (building pits). Oil, grease, and debris tend to accumulate, and insufficient cleaning can cause clogs and odors.

Venting Systems

These systems, such as vent pipes and vent valves, allow drainage to flow smoothly. If venting is insufficient, drainage flow may become poor, and the trap seal (water inside the drain trap) may be lost, causing odors and pest intrusion.

Other Related Equipment

Hot water supply systems are also closely related to plumbing systems. Depending on the building use, such as hospitals, factories, or commercial facilities, it is important to identify which equipment should be checked with particular attention.

Signs in Water Supply Systems

• Water pressure becomes unstable
• Unusual noise or vibration comes from the pump
• Red water or turbidity appears

Signs in Drainage Systems

• Drainage flow is poor
• Gurgling noises occur
• Odors occur
• Rather than assuming that everything is fine because the system can still be used, we recommend checking it early.

Maintenance Inspection Points: Water Supply System Section

The two highest priorities for water supply systems are maintaining water quality and ensuring stable pump operation.

Check Items for Water Storage Tanks (Receiving Water Tanks and Elevated Water Tanks)

If the system qualifies as a Building Water Tank System under Japanese law, it must be cleaned at least once a year and undergo a statutory Building Water Tank System Inspection once within every year. The following items are also checked during inspections.

• Cracks, deterioration, algae or rust, and sediment inside the tank
• Cracks or rust on the exterior of the tank, and damage or defects in the manhole cover
• Condition of the overflow pipe, vent pipe, and insect screens
• Residual chlorine measurement (maintaining free residual chlorine of at least 0.1 mg/L at the water tap)

Records of inspection and cleaning can also serve as evidence that the management system is appropriate if a problem occurs. In buildings with a direct water supply system, regular inspections focus on booster pumps and backflow prevention valves.

▶ Related page：What Is Water Storage Tank Cleaning? Its Necessity, Work Details, Process, and Costs

Water Supply Pump Operation Management

The water supply pump can be described as the “heart” of the building. The main items to check during inspection are as follows.

• Presence or absence of unusual noise and vibration
• Consistency between rated/set values and actual measured values for pressure gauges, current, and voltage, as well as insulation resistance values, etc.
• Alarm history, operating frequency, and number of starts/stops of the control panel, etc.
• Water leakage from shaft seal sections (mechanical seals, etc.) and piping

In buildings that have aged, attention must be paid not only to the pump itself but also to corrosion at pipe connections.

Maintenance Inspection Points: Drainage and Venting System Section

The two important points are preventing clogs and implementing odor and pest control measures. Oil, grease, scale deposits, and rust inside drainpipes become harder the longer they are left, making them difficult to remove even by high-pressure cleaning. Taking a preventive maintenance approach, rather than responding only after drainage becomes impossible, ultimately leads to cost reductions.

Preventing Drainpipe Clogs

Regular high-pressure cleaning is one effective way to prevent drainpipe clogs. For buildings that qualify as specified buildings under Japan’s Building Sanitation Law, drainage-related equipment must be cleaned at least once every six months. On the other hand, because no clear regulation has been confirmed that specifically sets the frequency or method for periodic high-pressure cleaning of drainpipes themselves, it is important to carry it out systematically according to the building’s use and operating conditions.
For typical apartment buildings, cleaning about once every one to two years is often used as a guideline. However, in buildings with restaurant tenants, oil and grease accumulate quickly, so shorter cleaning cycles may be required. In addition, checking for clogged vent pipes and malfunctioning vent valves can help reduce the risk of poor drainage and odors.

▶ Related page：Prevent Water Problems in Apartment Buildings with Regular Drainpipe Cleaning