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Defect library

Plumbing defects in new builds

Plumbing defects can stay hidden until water has been running for a while, which is why a slow leak under a floor may only show weeks after moving in. Run every tap and flush every toilet during the inspection, and find the stopcock before you need it.

Updated 19 October 2026

SiteSnag’s library has 17 entries under plumbing, and 2 of them are marked as safety or critical items. They’re listed below with the most serious first. Each one gives the wording an inspector would put in a report and the trade that would fix it, and 11 carry a reference to the standard or guidance they relate to. The references help you look up the relevant section and aren’t a statement that a particular home does or doesn’t comply.

All 17 entries

  1. Leaking pipework / fitting

    Critical

    Leak observed from pipework or fitting. Repair immediately to prevent damage.

    Trade
    Plumber
    Reference
    NHBC Standards 8.1

  2. Hot water too hot at bath (no TMV)

    Safety

    Bath hot water exceeds safe temperature; no thermostatic mixing valve. Fit TMV.

    Trade
    Plumber
    Reference
    Approved Document G

  3. Hot water cylinder fault

    Major

    Cylinder not heating, leaking or discharge pipe incorrect. Repair.

    Trade
    Plumber
    Reference
    NHBC Standards 8.1

  4. Lead water pipes

    Major

    Lead supply pipework present. Recommend replacement.

    Trade
    Plumber
    Reference
    None listed

  5. Slow draining waste

    Moderate

    Waste drains slowly. Check traps and gradients, clear blockage.

    Trade
    Plumber
    Reference
    NHBC Standards 8.1

  6. Toilet not flushing correctly

    Moderate

    WC does not flush/refill correctly. Adjust or replace cistern mechanism.

    Trade
    Plumber
    Reference
    NHBC Standards 8.1

  7. Low water pressure / flow

    Moderate

    Poor pressure or flow at outlet. Investigate and rectify.

    Trade
    Plumber
    Reference
    None listed

  8. Pipework not insulated in cold area

    Moderate

    Pipework in loft/unheated space not insulated. Insulate.

    Trade
    Plumber
    Reference
    Approved Document L

  9. Overflow discharging

    Moderate

    Cistern or tank overflow discharging. Adjust float valve.

    Trade
    Plumber
    Reference
    None listed

  10. Stopcock inaccessible / seized

    Moderate

    Stopcock not accessible or will not operate. Free off or relocate.

    Trade
    Plumber
    Reference
    None listed

  11. Hot and cold taps reversed

    Minor

    Hot and cold supplies connected the wrong way round. Correct the connections.

    Trade
    Plumber
    Reference
    NHBC Standards 8.1

  12. Water hammer / noisy pipework

    Minor

    Pipework knocks or hammers. Secure pipes / fit arrestor.

    Trade
    Plumber
    Reference
    None listed

  13. Outside tap not working / no isolation

    Minor

    Outside tap does not work, leaks or has no internal isolation. Repair.

    Trade
    Plumber
    Reference
    NHBC Standards 8.1

  14. Hot water slow to arrive

    Minor

    Long wait for hot water at outlets. Investigate pipe runs.

    Trade
    Plumber
    Reference
    NHBC Standards 8.1

  15. Isolation valves missing

    Minor

    Isolation valves not fitted to taps, WC or appliances. Fit.

    Trade
    Plumber
    Reference
    NHBC Standards 8.1

  16. Pipework not clipped / visible

    Minor

    Pipework loose, unclipped or exposed where it should be hidden. Clip and box in.

    Trade
    Plumber
    Reference
    NHBC Standards 8.1

  17. Water meter / stopcock location unknown

    Minor

    Location of the stopcock or water meter not identified. Locate and label.

    Trade
    Plumber
    Reference
    None listed

Using these in a report

In the SiteSnag app, starting to type a defect title in the camera brings up these entries. Picking one fills in the description, severity, trade and reference, and you can edit the wording or add your own defects to the library. Every snag then goes into the branded PDF report with its photos and a numbered pin on the floor plan.

For a room-by-room walk-round, use the new build snagging checklist, or go back to all defect categories.

Other categories

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