Plumbing & Drainage
QA inspection checklist

Pipework

1. 1.

   Pipe material and size match design
   What to look forPipe material per design — copper (BS EN 1057), MDPE for cold supply (BS EN 12201), PEX-AL-PEX or PB push-fit, MLCP for radiator circuits. Diameter measured at OD; legend on pipe. Not mixing materials at fittings without correct adapters.
   Acceptable whenPipe to BS EN 1057 (copper), BS EN 12201 (MDPE), BS 7291 (plastic hot/cold), BS EN 12831 (heating). Sizing per BS EN 806-3 / CIBSE Guide G — typically 22 mm cold mains feed, 15 mm branches, 10 mm to basin only short run.
   StandardBS EN 806-3:2006 — Internal water pipework sizing. BS EN 1057:2006+A1:2010 — Copper tube. BS 7291-1 to 4 — Plastic pipes. Water Regulations 1999.
   Common defectsPlastic pipe used within 1 m of boiler outlet — not heat tolerantMDPE used internally where copper or PEX specifiedUndersized pipes — flow rate at outlet inadequateLead solder used (banned for potable since 1987)Mixed metals (copper to galvanised) without dielectric union
2. 2.

   Falls on drainage correct

   Record: Fall (1 in ?)
   What to look forFalls measured with spirit level over a metre length, or by surveying levels along run. Above-ground wastes 1:40 to 1:110 (per pipe size). Below-ground 1:40-1:80 typical. No back-falls or flat sections. No standing water at low points.
   Acceptable whenAbove-ground per BS EN 12056-2: 32 mm = 1:18-1:44, 40 mm = 1:18-1:44, 50 mm = 1:24-1:48, 100 mm = 1:40-1:110. Below-ground per BS EN 752: foul minimum 1:80 for 100 mm, surface water 1:100. Maximum velocity 4 m/s.
   StandardBS EN 12056-2:2000 — Sanitary pipework. BS EN 752:2017 — Drain and sewer systems outside buildings. Approved Document H.
   Common defectsInsufficient fall — solids deposit, blockage developsFall too steep — water races, leaves solids behind ("self-cleansing velocity" not maintained)Back-fall at fittings — water pools, smellsFlat run between supports — sag in plastic pipework
3. 3.

   Clips and supports at correct centres
   What to look forPipe clips correct material and size. Centres per material — copper 1.2-2.4 m horizontal, plastic tighter. Supports at fittings, at junctions, and within 150 mm of bends. No long unsupported spans causing sag.
   Acceptable whenCopper: 15 mm = 1.2 m horizontal/1.8 m vertical, 22 mm = 1.8/2.4, 28 mm = 1.8/2.4. Plastic 15 mm hot = 0.5 m, cold = 0.8 m. PVC waste: 32-40 mm = 0.5 m, 50 mm = 0.6 m, 100 mm = 1.0 m. Per BS 8000-15.
   StandardBS 8000-15:1990 — Workmanship — Plumbing. BS EN 12056-2. Manufacturer's installation guides.
   Common defectsPlastic pipe sagging between supports — fall ruinedWrong clip size — pipe loose, knocks under flowPlastic clip on copper hot pipe — clip melts/distortsNo support at fittings — joint stressClip into plasterboard with no fixing into substrate
4. 4.

   Insulation complete
   What to look forInsulation continuous on hot pipes (energy), cold mains (anti-condensation/freeze), and frost-vulnerable runs. Joints butted, taped or zipped. Bends fully covered. Thickness per Building Regulations / Part L.
   Acceptable whenHot pipe insulation per Part L / Domestic Heating Compliance Guide: 22 mm pipe = 25 mm insulation thickness (lambda 0.04). Cold pipes in unheated spaces require frost protection — typically 19-25 mm. Insulation to BS 5422.
   StandardBS 5422:2009 — Thermal insulation specification. Approved Document L (energy). Domestic Heating Compliance Guide (DCLG).
   Common defectsBends not covered — split sleeve missing at elbowsInsulation slipped to one end of run — sections of bare pipeWrong thickness — 13 mm used where 25 mm required for Part LCold pipe in loft uninsulated — burst pipe riskInsulation left off above ceilings to chase programme
5. 5.

   Fire collars at penetrations
   What to look forPlastic pipes through fire-rated walls/floors fitted with intumescent fire collar (or fire sleeve for thinner walls). Collar matches pipe diameter. Fixed mechanically with screws/anchors. Both sides of penetration treated where applicable.
   Acceptable whenFire stopping per BS 9999, tested to BS EN 1366-3. Fire collar rating to match wall/floor (typically 60 or 120 minutes). Third-party certified product (LPCB / IFCC). Combustible pipes (PVC, ABS, PP, PE) must be sealed; copper and steel pipes can be sealed with fire mortar/intumescent sealant only.
   StandardBS EN 1366-3:2021. BS 9999:2017. Approved Document B. ASFP "Pink Book".
   Common defectsPlastic pipe through fire wall with no collar — fire pathCollar undersized — does not crush pipe completely on activationCollar fixed on one side only of two-leaf wallWrong rating — 60 min collar in 120 min wallNo labelling — not registered on as-installed log

Testing & Commissioning

1. 6.

   Pressure test passed

   Record: Pressure (bar)
   What to look forPressure gauge calibrated. Test pressure held for required duration without fall. Drop indicates leak — investigated. Test on segments before concealment. Above-ground drainage tested with air or water; below-ground typically air or water column.
   Acceptable whenHot/cold water pressure test per BS EN 806-4: 1.5 × working pressure (typical 9-15 bar) for 30 minutes, max 0.6 bar drop. Heating system per BS EN 14336: 1.5 × max operating, hold 30 min. Foul drainage air test per BS EN 1610: 100 mm WG falling to no less than 75 mm in 5 min.
   StandardBS EN 806-4:2010 — Installation of water supply systems. BS EN 14336:2004 — Installation of heating systems. BS EN 1610:2015 — Drainage construction and testing.
   Common defectsPressure drop ignored — assumed to be temperature-relatedTest pressure below 1.5 × working — may not reveal leaksGauge uncalibrated — false readingTest for too short duration — slow leak missedTest bypassed entirely on below-ground drainage
2. 7.

   Hot water temp at outlets

   Record: Temp (°C)
   What to look forWater drawn for 1 minute before measuring. Measure at outlet, not at meter. TMV-protected outlets show ≤ 43°C (basin), ≤ 41°C (bath/shower). Stored water ≥ 60°C for Legionella control. Distribution maintained ≥ 50°C.
   Acceptable whenPer HSG 274 / L8: hot water stored ≥ 60°C, distributed ≥ 50°C (55°C recommended), return ≥ 50°C. TMVs: bath 44°C, shower 41°C, basin 41°C, bidet 38°C per BS 7942 / NHS Estates HTM 04-01. Cold water ≤ 20°C.
   StandardHSG 274 Part 2 — Legionnaires' disease control. BS 7942:2015 — TMV3. NHS Estates HTM 04-01 — Water systems.
   Common defectsStorage temperature < 60°C — Legionella riskCold water > 20°C — return pipe/heating bridge contaminating cold supplyTMV temperature out of band — valve drift, needs serviceOutlet not run long enough — measurement of cold "first draw"No commissioning sheet recording temperatures
3. 8.

   Flushing and chlorination completed
   What to look forSystem flushed at high velocity to remove debris. Chlorination dose held for required contact time. Disinfection samples taken pre-handover and tested at UKAS lab. Records issued.
   Acceptable whenPer BS EN 806-4 / BS 8558: flush at velocity ≥ 1 m/s. Disinfection: 50 ppm free chlorine for 1 hour, or 20 ppm for 8 hours. Microbiological test post-disinfection: ≤ 1 cfu/ml total viable count, no E. coli/coliforms in 100 ml.
   StandardBS EN 806-4:2010. BS 8558:2015 — Guide to design, installation, testing and maintenance of services supplying water for domestic use. HSG 274.
   Common defectsFlush at insufficient velocity — debris remains in dead legsChlorine dose neutralised before correct contact timeNo microbiological sample taken — handover with no proof of cleanlinessDisinfectant not flushed out fully — chlorine taste at outletsRecords absent
4. 9.

   Commissioning certificates issued
   What to look forPack includes: pressure test record, temperature commissioning, flushing/chlorination certificate, microbiological test results, gas certificate (where gas-fired), Benchmark book for unvented cylinder (if applicable).
   Acceptable whenCommissioning records per BSRIA BG 2 — Commissioning water systems. Unvented cylinder G3 commissioning by competent person (registered scheme). Building Regulations notification (Part G) for hot water/cold water systems.
   StandardBSRIA BG 2/2010 — Commissioning water systems. Approved Document G. CIBSE Commissioning Code W.
   Common defectsPressure test certificate undated or signed by non-competent personMicrobiological certificate from non-UKAS labUnvented cylinder G3 not signed off — illegal in dwellingBenchmark book missing — manufacturer warranty voidCommissioning records "filled in later" — not concurrent with works

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