Potable supply, hydraulics, hot water and hygiene
Define the supply and its hydraulic conditions
A potable-water installation must deliver suitable water to the intended outlets without introducing contamination or an inappropriate pressure condition. Static pressure, pressure during flow and pressure loss are different quantities. A hydrostatic model uses density, gravitational acceleration and height, while flowing systems also involve friction and local losses. Pipe diameter, length, roughness, fittings and demand influence performance. A large static gauge reading does not guarantee sufficient flow at a remote outlet, and a pressure reduction device is not interchangeable with a check valve.
Preserve separation and water quality
A cross-connection creates a potential route between potable and nonpotable systems. Backpressure and backsiphonage can drive unwanted flow by different pressure mechanisms. Appropriate separation or protective devices must match the actual hazard and applicable requirements; one generic valve is not sufficient for every contamination category. An air gap is a physical separation when correctly designed and maintained. Identify risks from hoses, chemical treatment, equipment connections, storage and maintenance rather than assume clear-looking water is microbiologically safe.
Coordinate hot-water performance and safety
Heating water changes its volume and can increase pressure in a constrained system. Expansion accommodation and temperature or pressure protection have different roles. A relief device must remain an effective designed protection, not be isolated because it discharges. Mixing devices, storage, circulation and point-of-use conditions influence both hygiene and scald risk. Legionella risk management needs the actual current Swiss health and technical basis, appropriate temperatures, flow/use patterns and maintenance; no universal disinfection recipe or limit is invented here.
Maintain materials and operational evidence
Choose suitable pipe, joint, seals and components for the water chemistry, temperature, pressure and intended potable service. Material identity and compatibility matter beyond a similar outside diameter. Stagnation, poorly used branches, sediment and biofilm can create concerns that a cosmetic finish does not resolve. Commissioning and water sampling must follow their defined purpose and competent procedure; an arbitrary flush is not proof of hygienic acceptance. Record relevant conditions, tests and responsibilities. These written foundations support Swiss sanitary-master judgment but do not authorize chemical disinfection, public-water alteration or a complete current practical or legal qualification.