Water supply piping 101
Water supply piping must be considered in waterproofing projects from the start, whether on rooftops, exterior walls, or bathrooms in residential buildings. Penetrations where pipes pass through membranes are common leakage points, so flashings and sealants must be compatible with the chosen membrane and the surrounding substrate throughout the assembly. Before finishing, perform a hydrostatic test to verify both the piping layout and waterproof layer hold without seepage under expected seasonal pressure in the field.
During installation, route pipes along protected routes and maintain proper slope to drain systems, avoiding sharp bends that trap water and compromise membranes, and reduce noise transmission. Choose piping materials that tolerate movement and temperature changes without cracking, such as copper, PEX, or high-grade PVC, and verify compatibility with insulation in concealed wall cavities. Use sleeving, grommets, and fire-rated sealants to protect pipes at joints and prevent water tracking behind walls, especially where walls meet floors or ceilings during renovations.
Materials and corrosion
Materials for water supply piping vary in durability and corrosion resistance, so select based on environment, local codes, and anticipated maintenance cycles and climate conditions. Copper remains reliable but can suffer from galvanic corrosion when in contact with incompatible metals behind membranes, so isolation strategies are essential in dense assemblies. PEX and CPVC offer flexibility and easier sealing with modern waterproofing systems, reducing crack paths and simplifying long-term service life over time.
Ensure metal and plastic components are isolated with appropriate bushings and sleeves to prevent corrosion at penetrations and to maintain membrane integrity in the wall and roof zones. Consider oxygen barrier PEX for long-term durability, especially in multi-layer waterproofing assemblies where moisture-driven corrosion is a concern in concrete structures. Compatibility with waterproof membranes, joint sealants, and roof or wall finishes is essential to prevent delamination and future moisture migration and failures.
Inspection and upkeep
Routine inspection of water supply piping after waterproofing work helps catch hidden leaks early and preserves wall integrity over a building's lifetime and occupant safety. In apartments or multi dwelling buildings, schedule periodic leaks detection and respond quickly to any moisture signs before visible damage spreads or mold growth. Use moisture meters to monitor behind walls and maintain an ongoing maintenance plan that includes seasonal checks and documented repairs for the future.
Check penetrations at sinks, boilers, and external faucets for signs of movement or sealant degradation due to temperature cycles. Redo sealing around pipes after major renovations or temperature fluctuations to maintain waterproofing performance and avoid rework costs and material failures. Plan for eventual pipe replacement before failure, as aging systems rarely fail all at once, and early replacement minimizes water damage risk in your building.