Pipework Replacement in a tall building (over 18m below 50m)

 With the new Safety Act now being in-forced there are new regulations and guidelines when installing or replacing pipework that rises through a building, this now affects all buildings over 18m. Here’s a comprehensive compliance checklist for the refurbishment of potable cold water pipework in apartment buildings over 18 metres tall in England (as of 2025). This is tailored for engineers, contractors, and project managers working on occupied or partially occupied buildings.

 Refurbishment Compliance Checklist for Potable Cold Water Pipework (18m+ Buildings)

 Pre-Design / Survey Stage

 ·         Assess existing water services layout and condition
→ Identify main risers, branches, tank locations, booster sets, dead legs, stagnation points.

·        Identify WRAS compliance of existing pipework and fittings
→ Replace any non-WRAS-approved or degraded materials (e.g. old copper with lead solder, galvanised steel).

·        Check existing storage and booster configuration
→ Ensure water supply meets current demand and pressure standards.

·        Legionella risk assessment (as per HSE L8 / HSG274)
→ Mandatory before changes are made; assess risk of contamination or bacterial growth.

·        Fire stopping and compartmentation review
→ Pipes must not compromise fire integrity through walls/floors; check fire collars/sleeves.

·        Engage with water undertaker (e.g. Thames Water)
→ Notify refurbishment and confirm backflow protection requirements.

 Design Stage

 ·        Conform to Water Supply (Water Fittings) Regulations 1999
→ Design must avoid cross-connections, backflow, dead ends, and use approved materials.

·        Comply with BS 8558 and BS EN 806 (Parts 1–5)
→ Include pressure zones, correct pipe sizing, insulation, flow velocity limits (<3 m/s recommended).

·        Address pressure zoning
→ For tall buildings, implement:

o   Break tanks (if necessary)

o   Booster sets with PRVs

o   Zonal isolation and control       

·        Confirm pipe insulation to prevent heat gain
→ Cold water pipes must be insulated to prevent Legionella risk and energy loss.

·        Allow for flushing points and commissioning access
→ Especially at top floor ends of risers and at underused branches.

·        Backflow prevention to Fluid Category 3–5 standards
→ Use double check valves, RPZ valves, air gaps where needed.

 Installation Stage

  ·         Install only WRAS-approved components
→ Check product markings, certification, and materials compatibility.

·        Ensure secure fixing of vertical risers and branches
→ Prevent pipe strain and reduce water hammer.

·        Install isolating valves per zone/apartment
→ For ease of future maintenance or emergency shut-off.

·        Ensure correct pipe gradients and support spacing
→ Follow BS EN 806 guidance to prevent air locks and pipe sagging.

·        Label all pipework clearly
→ With direction of flow, type of water, and zone served.

·        Ensure fire compartment integrity is reinstated
→ With tested fire collars or sleeves for any pipe penetrations.

 Commissioning & Handover

 ·        Flush and disinfect all new pipework (BS 8558 / BSRIA BG 29)
→ Clean, chlorinate, and rinse systems before use. Test for:

o   Total viable bacteria count

o   E. coli / coliforms

o   Legionella (if applicable)       

·        Verify system pressure and flow at top floors
→ Ensure compliance with design minimums (typically >1 bar dynamic pressure at tap).

·        Check water temperature after stagnation
→ Cold water should be <20°C within 2 minutes at all outlets (HSG274 Part 2).

·        Provide as-built drawings and O&M manuals
→ Include isolation points, valves, flushing points, and product warranties.

·        Train facilities/maintenance staff
→ On valve use, flushing regime, and routine testing.

 Post-Occupancy / Management

 ·        Implement written scheme of control for Legionella
→ Based on HSE ACoP L8; include routine flushing, testing, and inspection.

·        Log temperature checks at sentinel points
→ Ideally monthly.

·        Maintain water quality sampling records
→ Especially for any building with break tanks or booster sets.

·        Check for signs of stagnation or low-use outlets
→ Retrofit secondary circulation loops or auto-flushing devices if needed.

 Notes:

·        For partial refurbishments, care must be taken not to introduce contamination to existing systems.

·        Occupants should be notified of water interruptions and flushing schedules.

·        A temporary bypass or staged switchover may be needed to ensure continued supply during works.

 

Once water pipe replacement work in a building over 18 m in height is completed—especially riser replacement—the responsibility for checking compliance depends on the type of work and what standards are being applied.

 Here’s a breakdown of who should check what:

 Building Control / Approved Inspector

 When involved: Always for structural work, compartmentation breaches (e.g. floor penetrations), and tall buildings.

  • What they check:

    • Fire-stopping at floor penetrations (for risers going through fire-rated floors/walls)

    • Dry/wet riser provisions (if new fire-fighting pipework was added or altered)

    • Pipe routes that pass through protected shafts, escape routes, or service risers

    • How: Must inspect or sign off physical works, often via site visits or evidence (photos, fire stopping logs).

 Water Undertaker (e.g. Thames Water)

 When involved: When the work affects the incoming mains water supply or includes backflow prevention.

  • What they check:

    • Compliance with the Water Supply (Water Fittings) Regulations 1999

    • Correct use of backflow prevention devices, pipe materials, and fittings

    • Notification and approval may be needed before work starts for:

      • Pipework over 135 litres capacity

      • Buildings over 18 m if storage/booster sets are involved

         

  • How: They may request inspection or require a certified WaterSafe or WIAPS plumber to do the work and self-certify.

 Fire Engineer / Fire Risk Assessor

 When involved: Any penetrations through fire-rated floors/walls, changes to risers in protected shafts, or addition of dry/wet risers.

  • What they check:

    • Compartmentation maintained

    • Firestopping certified and labelled

    • Risers don’t compromise escape or smoke control

    How: Can sign off on fire-stopping or compartmentation reports, or inspect the fire safety performance of service risers.

 Commissioning Engineer or Specialist

  When involved: For pressure testing, chlorination, and flow/pressure commissioning.

  • What they check:

    • System is pressure-tested to 1.5× working pressure

    • Chlorination and flushing is completed to BS 8558

    • Valves, isolation, and access are all serviceable 

  • How: Provide test certificates, flushing records, and commissioning sheets.

 Responsible Person (Building Owner/Manager)

 Ongoing responsibility: Ensuring that all inspections and certifications are completed and documented.

  • Should keep:

    • Fire-stopping certifications

    • Pressure/chlorination test results

    • As-built drawings showing riser routes and access

    • Water Regulations compliance evidence (esp. if notified)

 Summary Table

  Role What They Check

Building Control / Inspector Fire-stopping, compartmentation, fire riser provisions

Water Authority (Thames Water etc.) Compliance with Water Regs 1999, backflow, materials, pipework notifications

Fire Engineer / Assessor Firestopping, protected riser compliance, compartmentation

Commissioning Engineer Pressure tests, chlorination, flow/pressure verification

Responsible Person / Owner Holds records and ensures compliance certificates are filed and accessible

 Who Certifies the Work?

 If using competent professionals:

 A WaterSafe or WIAPS certified plumber can self-certify water pipe installations.

  • A third-party fire-stopping contractor (e.g. FIRAS accredited) can certify penetrations.

  • A commissioning engineer can certify pressure/chlorination.

  • Final sign-off may need to come from Building Control or an Approved Inspector.

 Here’s a practical checklist and a sample sign-off form template you can use when replacing rising water pipework in a building over 18 m. It’s tailored for both open and concealed risers and includes all key compliance areas (fire, water regulations, pressure testing, etc.).

 Rising Pipework Replacement – Handover Checklist

 General Information

  Project name / address

  • Date of completion

  • Description of works

  • Contractor name and accreditation (e.g. WaterSafe, WIAPS, FIRAS)

 Pipework Installation 

  • Pipe material complies with BS EN 806 and Water Regs (e.g. copper, steel)

  • All joints accessible (no buried/embedded fittings)

  • Pipe supports and fixings at correct intervals

  • Pipework insulated and protected from corrosion

  • Routes recorded on updated “as-built” drawings

 Fire Stopping / Compartmentation

  • All floor and wall penetrations sleeved and sealed

  • Fire stopping completed and labelled

  • Products used (e.g. Rockwool, Hilti) are 4-hour rated (where required)

  • Compartmentation diagrams updated

  • Fire stopping certificates included from accredited contractor (e.g. FIRAS)

 Pressure Testing & Commissioning 

  • Pipework hydrostatically tested to 1.5× system pressure

  • Test pressure held for minimum 1 hour without drop

  • Chlorination and flushing completed to BS 8558

  • Lab test certificate for residual chlorine / bacteria

  • Commissioning records signed off

 Compliance with Water Regulations 

  • Backflow prevention installed where required (RPZ, double check valve)

  • Notification sent to Water Authority if over 135L or boosted

  • Materials in contact with water are WRAS approved

  • Certification by WaterSafe or WIAPS installer (if applicable)

 Fire Riser / Dry Riser (if applicable) 

  • Installed per BS 9990 (dry riser if >18 m, wet if >50 m)

  • Hydraulically tested and certified

  • Inlet and outlet points labelled and capped

  • Inspection hatch provided at each floor landing

  • Maintenance log started (6-month visual, annual hydraulic)

 Documentation (to be included in O&M Manual) 

  • As-built drawings showing pipe routes and access points

  • Pressure test certificate

  • Chlorination/disinfection certificate

  • Fire stopping certificate

  • Product data sheets (WRAS approved materials)

  • Fire strategy / riser diagrams (if applicable)

 Notes:

 - All installation works comply with BS EN 806, BS 8558, Water Supply (Water Fittings) Regulations 1999, and BS 9990 (where applicable).

- All penetrations have been fire-stopped and certified.

- Documentation has been provided to the building manager.