[Post-earthquake health checkup of old houses in Taipei] Is it safe if the walls are not cracked after the earthquake? Water and electricity experts teach you three ways to troubleshoot "hidden pipe leaks in the wall" and the risk of loose gas pipes

Invisible killer after the earthquake: Why is the wall not cracked, but the water pipe may be leaking?

Taiwan is located at the junction of tectonic plates. The proportion of old apartments in the greater Taipei area is extremely high, especially in old community groups such as Banqiao, Zhongyonghe, Xindian and Daan. There are many apartments that are more than 30 years old. When a strong earthquake occurs, the building structure will undergo slight twisting and displacement that is difficult to detect with the naked eye. Although the beams and columns appear to be intact on the outside, old water supply pipes (such as galvanized iron pipes or PVC plastic pipes commonly used in the early days) buried in brick walls or concrete shear walls are often torn at pipe joints and elbows due to lack of elasticity. This kind of tiny leakage will not be noticeable for a short time. After a few weeks or months, mold spots will begin to appear on the wall, or water will leak through the floor and drip onto the ceiling of the neighbor downstairs, often causing corrosion of steel bars and serious structural damage. For investors or commercial buyers who plan to buy a house to live in or renovate (flip) an old house, damage to hidden pipes after the earthquake is an easy financial landmine and source of disputes over neighbor damage when assessing the value of assets.

The first step: Insulation water cutoff "water meter pointer micro-movement test method"

When plumbers conduct non-destructive leak detection, the most basic and scientific method is to observe the water meter. The first step in the independent investigation is to turn off all water outlets in the home, including kitchen and bathroom faucets, shower valves, and the water inlet triangle valve behind the toilet, and temporarily turn off household appliances that automatically replenish water, such as water heaters and ice machines. At this time, go to the top or first floor of the building to find your water meter. Observe carefully the small red triangular pointer in the center of the water meter dial (the micro flow rate indicator). If the triangular pointer is still rotating slowly even when there is no water at all, or the pointer scale recorded every half hour increases, it means that there is a continuous leak in the pipeline from the water meter to the indoor water outlet. At this time, you should immediately ask a professional water and electricity company to bring pressure detection equipment for segmental positioning.

The second step: Hidden pipe water pressure pressurization and pressure drop detection method

To thoroughly diagnose the integrity of hidden water pipes in the wall, hydropower projects will use "pressure drop testing". The construction steps are to first remove all indoor water supply terminals, install air-tight plugs, and install precision pressure gauges at the water outlets. Then use a pressure test pump to inject clean water into the pipeline, pressurize it to 1.5 to 2 times the daily water supply pressure (about 5 to 7 kg/cm2), then close the pressure valve and wait for 20 to 30 minutes. If the scale of the pressure gauge drops, you can be 100% certain that the pipe section is damaged. For earthquake-proof repairs of old houses, the current industry standard is to replace fragile old pipes with "stainless steel crimped pipes" (cold water pipes) and "coated insulated stainless steel crimped pipes" (hot water pipes). Their metal toughness and seismic strength are much higher than traditional plastic pipes. They are also an important bonus for commercial investors to significantly increase the value of mechanical and electrical assets when raising house valuations and packaging disaster-proof homes.

The third step: troubleshooting of loose gas pipelines and anti-shock automatic shut-off valves

In addition to water pipes, gas pipes and water heater joints are more dangerous after the earthquake. Strong earthquake shaking often causes the metal bellows joint under the water heater or the kitchen gas rubber hose to become slightly loose at the connection point. Water and electricity experts suggest that after an earthquake, soapy water should be applied to all exposed gas pipeline joints, explosion-proof hoses and Cock switches. If small bubbles continue to appear, it means that a small amount of gas is leaking. Many apartments in the greater Taipei area still use traditional natural gas meters. It is recommended to install a "microcomputer self-recording safety gas meter" during water and electricity repairs. When an earthquake of magnitude 5 or above or abnormal flow is detected, the computer will automatically cut off the gas immediately. For a large number of landlords or property purchasers who own old houses for rent, upgrading microcomputer gas meters and anti-seismic pipes is the best risk control strategy to reduce insurance premiums and protect commercial assets from secondary fires.

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 the contract for the project, be sure to clearly specify the waterproofing warranty period (usually 1 year for partial repairs, and 2 to 5 years for the whole 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.