[Investigation of Public Water Supply in Old Apartments] Is the top floor of an old apartment in Taipei covered with a cap to crush the main pipe? "Vertical shift of public water supply lines" and adjustment of uneven water pressure on each floor

A leaky Rashomon gate was built on the top floor of an old apartment in Taipei that crushed the public water main pipe

In the Greater Taipei area (such as early development areas such as Zhonghe, Yonghe, Banqiao, Sanchong, etc.), up to 70 to 80% of the top floors of apartments that are over 40 years old have early "top floor additions (top additions)" illegal construction. During the construction of these illegal buildings, it is often convenient to directly cover the "public water supply main pipe (water tower outlet pipe)" of the entire apartment building inside the illegally built RC floors or brick walls. As time went by, these public iron pipes buried under the illegal construction corroded and leaked, and water leaked downwards, causing serious wall cancer on the ceilings of the fourth or fifth floors. At this time, the law and Rashomon repairs will be extremely difficult: the residents on the fourth floor ask for the leak to be repaired, but the owner of the roof extension refuses to let people enter the house to knock out the floor; or the pipelines belong to public property rights, and the management committee (or all residents) are unwilling to bear the additional demolition and restoration costs caused by illegal construction. This dilemma of public pipelines being "crushed" by illegal construction has long been the most troublesome neighborhood conflict in Shuangbei's water and electricity repairs.

Engineering configuration of "vertical shifting" of public pipelines and "external wall open pipe diversion"

In order to solve the deadlock of public water mains being trapped in illegal buildings and unable to be repaired, modern hydropower projects usually adopt a thorough solution of "exposed external walls and vertical displacement of pipelines":
1. Cut off the main pipes between existing pipes: The plumbers will directly cut off and seal the old iron pipes that originally led to the pipes on each floor under the main water outlet of the public water tower on the top floor.
2. Independent external piping (stainless steel exposed pipes): Along the outer wall of the apartment's back balcony or the outer wall of the public stairs, re-install independent water supply pipes that meet the specifications of each household's water meter. The cold water pipes are made of SUS304 stainless steel pipes, which are constructed and fixed on the exterior wall using the double crimping method. The pipes are wrapped with sun-proof foam pipes or installed with stainless steel protection grooves (pipe grooves) to prevent the water pipes from aging due to outdoor wind and sun.
3. Access to the back balcony of each household: The exposed pipes on the exterior wall extend all the way down, and holes are drilled on the back balcony of each floor (usually next to the water inlet of the washing machine or water heater) to connect to the indoor waterway and connect to the existing indoor waterway of each household. This construction method can completely bypass the illegal construction on the top floor and complete the renewal of the entire water supply pipe without entering the homes of residents on the top floor. Property rights and maintenance responsibilities are clear at a glance.

Uneven water pressure in multiple households: adjustment of pressure reducing valve, pressurizing motor and height difference of water tower on the top floor

When reconfiguring the water supply system in old apartments, the problem of uneven water pressure is often caused by "insufficient water pressure on high floors and excessive water pressure on low floors." Water and electricity experts have the following adjustment strategies:
1.According to water physics, the hydrostatic pressure increases by 0.3 kg/cm² for every floor dropped (approximately 3 meters of height difference). Residents on the first floor of a five-story apartment building may experience water pressure of more than 3.0 kg/cm². Excessive water pressure will cause a violent "water hammer" when indoor faucets are turned on and off, shattering water pipe joints in the wall or damaging the water heater. Therefore, the water supply main lines on the first and second floors must be equipped with pressure reducing valves to stably control the water pressure entering the home between 1.5 and 2.0 kg/cm².
2.For residents on the fifth or fourth floor, because there is only a height difference of 1 to 2 meters from the water tower on the top floor (the hydrostatic pressure of the drop is only 0.1 to 0.2 kg/cm²), the water flow is often as thin as a stream and the shower head cannot be started. A "constant-voltage electronic pressurizing motor (1/4HP or 1/2HP)" must be installed behind the water meter on the top floor to provide a stable water pressure of 1.5 kg/cm². The electronic constant-voltage motor operates with a low sound, which can avoid disturbing the neighbors late at night.

Legal basis for resolving apartment public water supply disputes and practical coordination of water and electricity

For real estate purchasers and investors in the renovation of old apartments, when evaluating the purchase of old apartments in prime locations, the health of public waterways and the degree of negotiation for electricity and water use by neighbors are important indicators for evaluating the potential legal risks of the assets.
According to Articles 786 and 820 of Taiwan's Civil Code, if a public pipeline passes through someone else's proprietary portion, the owner of the proprietary portion has the obligation to tolerate it; however, if it is necessary to enter someone else's proprietary portion to repair a public pipeline, a method that will cause the least damage should be chosen, and the management committee or all co-owners have the right to redo the public water pipe by majority vote. Understanding these legal provisions and making good use of the low-conflict hydropower technology of "external wall stainless steel open pipe diversion" can resolve the original unsolvable deadlock of illegal construction and water leakage into a controllable and well-budgeted engineering transformation during acquisition negotiations. This not only ensures the water safety of the entire apartment, but also eliminates future water leakage litigation costs. It is a rare technical and practical skill for high-end real estate investors.

The latest standards for catching leaks and regulatory responsibilities in Shuangbei collective housing (2025-2026 practice)

According to Article 10 of the "Apartment Building Management Regulations" of the Ministry of the Interior and the trend of civil water leakage judgments in Shuangbei District Court in recent years, most water leakage disputes in old collective housing focus on the identification and definition of "exclusive parts" and "common parts". The roof platform and the public pipes are jointly owned by all separate owners, and the repair costs should be shared by public funds or all residents in proportion to their shares according to law; if the water supply and drainage pipes inside the floor slabs on the upper and lower floors are damaged, the pipes will be borne exclusively by the users or shared by the upper and lower floors.

At the engineering and technical level, modern professional leak detection has fully introduced non-destructive scientific testing, including "FLIR high-resolution infrared thermal imaging camera" (locating temperature difference leakage paths), "high frequency moisture meter" (measuring the moisture content of deep structures) and "pipeline air pressure and water pressure pressure test" (determining whether hot and cold water pipes are leaking). During construction, do not directly apply elastic cement or oil-based paint on the wet cement layer to seal it. Otherwise, the thermal expansion of internal water vapor will quickly cause the coating to blister and peel off, resulting in more serious powdery wall cancer. The standard construction method must first completely eliminate the water source, wait until the moisture content of the cement structure drops below 8%, and then apply the negative pressure resistant silicic acid permeability crystallized waterproof layer.

Recommendations on independent certificate storage and compensation process for water leakage repair

1. Take photos and videos as evidence immediately: Use rulers to record the leakage range, frequency of water discharge, direction of water mark diffusion, and keep time stamps.
2. Written notification and coordination survey: Officially notify the neighbors through the management committee or a certified letter, and agree on a professional third-party leak detection and appraisal unit recognized by both parties to conduct an on-site survey.
3. The contract states the warranty terms:When signing a contract for a project, be sure to clearly specify the waterproofing warranty period (usually 1 year for partial repairs, and 2 to 5 years for complete room or roof re-construction), and specify the water test acceptance criteria (such as a 48-hour water storage test in the bathroom shower area) to protect your own asset rights.