What this work covers
Pipe testing and covering is the approval stage before new supply and drain pipes disappear inside walls and floors. It checks pressure, flow, and backflow, fixes outlet positions and pipe supports, adds acoustic and thermal protection, and records the concealed routes for later work.
When this work is needed
New or extended concealed pipework should be tested and recorded before screed, waterproofing, or tile begins. A visible fitting replacement still needs a leak and flow check appropriate to its scope, but it does not automatically require the same whole-system hold test.
Set the acceptance criteria
Agree the test boundary, method, and person who can release the work for covering.
- Supply and drain sections under test and every temporary cap
- Starting pressure, hold time, and acceptance limit
- Drain-flow and backflow method and the outlets included
- Finished-wall and floor datums for tap elbows and drains
- Who approves repairs, retesting, photographs, and the final release
Check in the quote
Make sure testing is a visible deliverable rather than an assumed part of other plumbing work.
- Is a supply pressure test with a gauge and pump included?
- Are drain-flow and backflow checks carried out separately?
- Are tap elbows, pipe supports, drain soundproofing, and penetration packing included?
- Is insulation defined for condensation and freeze-risk areas?
- Are repairs, retesting, and photographic handover included after a failed test?
If you have test records or photographs before covering, I can help check whether the pipework is ready for the next trade.
What to check on site
Testing is not a final glance at finished pipework. It is the decision that the installation is safe to conceal, and pressure, flow, support, insulation, and records all need to pass.
- Complete pressure test
Pressurise the supply system to the agreed value and monitor the gauge and every joint for 24 hours. Run water from several fixture positions through the drains, checking blockage, backflow, and leaking joints, and record results by section. - Fix pipes and add soundproofing
Fix tap elbows and pipes so they cannot move by hand, and support drains so they do not strike the structure under flow. Do not hide joints that still need inspection beneath packing or acoustic wrap. - Cover, insulate, and record
Insulate pipework in external walls and unheated spaces for the actual condensation and freeze risk. Photograph the gauge, joints, complete routes, and reference dimensions before handing the approved installation to the waterproofing and screeding teams.
Where problems usually start
- Untested concealed joint If a small leak is covered without a pressure test, the screed and finishes may all need to be removed for access.
- Tap elbow position An elbow set at the wrong depth or angle forces excessive offset fittings and increases the risk of a tilted or leaking tap.
- Drain soundproofing Missing or broken acoustic wrap can transmit every water and waste discharge through walls and ceilings.
A pressure drop is not automatically a pipe leak. Verify the gauge, pump, and temporary caps, then isolate and repeat the test under the same conditions.
One gauge photograph cannot locate concealed services. Receive route photographs, reference dimensions, tap elbows, drains, acoustic wrap, and insulation grouped by room.
Timing and records
Allow about 8 to 16 hours for fixing, acoustic treatment, insulation, and preparation for covering, with the pressure hold separate. Repairs and retesting may delay waterproofing and screeding.
Keep test sections, starting and finishing pressures, hold time, flow and backflow results, repair and retest records, outlet dimensions, and room-by-room photographs of acoustic and thermal protection.
The installed pipework before the test and the waterproofing and screed after it show why this approval cannot be skipped.