Intro

On most jobs, plumbing work decides if the day ends smooth or messy. Leaks, slow drains, and failed tests eat time and profit. This guide shows how to run plumbing work from survey to sign‑off. You’ll see simple steps, key sizes, and test methods. We keep the language clear. You get solid results on site. Use this to brief your team, plan materials, and avoid come‑backs.

Quick Answer

Plumbing work means planning the route, first fix pipe runs, second fix connections, and final testing. Aim for correct falls, solid supports, and clean joints. Pressure test for 30–60 minutes, flush every outlet for 2–3 minutes, and deliver clear handover notes. Do this, and most call‑backs disappear.

Table of Contents

• Plan The Job
• First Fix Plumbing Work
• Second Fix Plumbing Work
• Drainage And Venting Done Right
• Quality Control, Documentation, And Handover
• Pricing And Time Estimates For Common Plumbing Work
• FAQ

Key Takeaways

• Set waste pipe fall around 18–22 mm per metre. That prevents blockages.
• Support copper every 1.2–1.5 m; plastic every 0.5–0.8 m. Less sag, fewer leaks.
• Pressure test for 30–60 minutes at 1–1.5× expected working pressure.
• Keep trap seals at 50 mm. Add air admittance valves when vent distances are long.
• Small bathroom first fix often takes 6–10 hours for one experienced plumber.

Plan The Job

Good plumbing work starts before tools come out.

1. Walk‑through survey

   • Mark every outlet and appliance. Note heights and clearances.
   • Confirm service entry points and main stop valve.
   • Check existing pipe sizes: 15 mm hot/cold, 22 mm feeds to baths/boilers, 110 mm soil.

2. Regulations and standards

   • Follow local building regs for drainage (commonly Approved Document H) and water (Water Fittings Regulations).
   • Aim for safe hot water. Store at about 60°C. Deliver at sinks around 50–55°C using thermostatic mixing where needed.

3. Material plan

   • Typical sizes: basin waste 32 mm, shower/bath 40 mm, kitchen sink 40–50 mm, toilet soil 110 mm.
   • Order valves, isolation taps, flexis, trap kits, clips, lagging (13–19 mm insulation on hot).

4. Time and access

   • Allow 3–10 days for any permits or notice, if required locally.
   • Plan noisy drilling when neighbours are out, if needed.

Tip: If you also want help with professional proposals and clear scopes, consider creating them before day one. It supports clean plumbing work on site and avoids scope drift.

First Fix Plumbing Work

First fix is the bones of your plumbing work: routes, falls, and supports.

1. Set routes

   • Keep hot on the left, cold on the right. Cross only when needed.
   • Avoid tight bends. Use long radius where possible.
   • Maintain fall on wastes: target 18–22 mm per metre. Too flat blocks. Too steep leaves solids.

2. Drill and notch safely

   • Keep to safe zones. Stay clear of edges and electrical runs.
   • Protect pipes through studs with plates.

3. Support correctly

   • Copper: clip every 1.2–1.5 m horizontal, 2.0–2.5 m vertical.
   • Plastic: clip closer, about every 0.5–0.8 m.
   • Add extra clips near valves and bends.

4. Joints and prep

   • Clean, deburr, and dry‑fit. Mark insertion depth on push‑fit.
   • For compression, keep pipe ends square. Do not over‑tighten.

5. Pressure test (before closing walls)

   • Cap outlets. Use a gauge and test pump.
   • Test for 30–60 minutes at 1–1.5× expected working pressure. Record results.
   • Fix any drops before boarding. Most contractors skip this step. Don’t make that mistake.

Second Fix Plumbing Work

Second fix finishes the plumbing work. Take your time here.

1. Fit isolation valves

   • One per outlet is best. It saves future call‑outs.

2. Connect fixtures

   • Use PTFE on male threads: 6–8 wraps, even and tight.
   • For solvent weld, dry fit first. Apply cement fully. Hold for 10–20 seconds. Allow 10–20 minutes to set before handling, longer if cold.

3. Align and level

   • Set basins and WCs level within 1–2 mm.
   • Use flexible connectors only where movement is needed. Avoid kinks.

4. Commissioning

   • Open slowly. Check each joint dry with a tissue.
   • Flush each outlet 2–3 minutes. Clear air and debris.
   • Set hot water delivery to about 50–55°C at outlets. Store cylinders near 60°C to limit Legionella risk.

5. Seal and finish

   • Use sanitary silicone. Leave a 1–3 mm neat bead.
   • Let it cure per label, often 24 hours, before heavy use.

Drainage And Venting Done Right

Poor venting ruins good plumbing work. Stop smells and gurgles.

1. Trap seals

   • Keep 50 mm water seal on basins, baths, and showers.
   • Avoid long flat waste runs that self‑siphon.

2. Venting options

   • Direct vent to stack if within common limits (often up to 3 m, check local rules).
   • Use an air admittance valve (AAV) when distance is long. Keep it accessible and above flood level.

3. Soil and waste routing

   • Maintain that 18–22 mm/m fall.
   • Provide cleanouts at changes of direction and every 5–10 m.
   • Use 110 mm for soil. Keep pan connectors straight and well‑sealed.

4. Drain testing

   • Water test: fill to required level and hold 10–15 minutes. Check for drops.
   • Smoke testing is also used by some teams to spot leaks at joints.

Quality Control, Documentation, And Handover

Strong paperwork backs up strong plumbing work.

1. Quality checks

   • Photo every concealed run before closing. Include a tape measure for scale.
   • Log clip spacing, falls, and test pressures.

2. As‑builts and O&M

   • Mark valve locations, isolation points, and AAV positions.
   • Note model numbers and warranties. Leave simple use and care notes.

3. Handover

   • Walk the client through stop valves. Show them how to isolate in 30 seconds.
   • Provide a brief snag form and respond within 24–48 hours.

4. Proposals and sign‑offs

   • Clear scopes reduce extras and disputes. Tools like Donizo help capture scope fast with Voice to Proposal, send branded PDFs, get e‑signatures, and convert accepted proposals into invoices in one click. That keeps your plumbing work aligned from quote to final bill.

Internal linking opportunities you can build on:

• See our guide on professional proposals to tighten your scope wording.
• Learn best practices for project timelines to plan first and second fix windows.
• Use invoice templates that save time when closing jobs.

Pricing And Time Estimates For Common Plumbing Work

Every site is different, but these rough times help plan plumbing work:

• Replace basin tap: 45–90 minutes (add 30 minutes if access is tight).
• Swap a close‑coupled WC: 2–3 hours including seal and test.
• New shower valve and head: 2–4 hours if pipe routes are ready.
• Full small bathroom first fix: 6–10 hours for one experienced plumber.
• Second fix same bathroom: 5–8 hours including silicone and testing.
• Trace and fix minor leak: 1–3 hours, plus 2–4 hours if tiles need lifting.

Add travel (30–60 minutes), materials pick‑ups (30–45 minutes), and clean‑down (20–30 minutes). Build these into your plan so plumbing work stays profitable.

FAQ

What is first fix and second fix in plumbing work?

First fix covers pipe routes, wastes, soil, and valve positions before walls close. Second fix is fitting the fixtures, final connections, sealants, and commissioning. Test at both stages. It keeps issues cheap to fix.

What pipe sizes are standard for typical plumbing work?

Commonly: 15 mm for most hot and cold feeds, 22 mm for baths/boilers or main branches, 32 mm basin waste, 40 mm shower/bath and kitchen sink waste, and 110 mm soil. Always check manufacturer instructions and local rules.

How much fall should I allow on waste pipes?

A good target is 18–22 mm per metre. Too flat and you get blockages. Too steep and water outruns solids. Keep it steady and well‑supported.

How long should I pressure test new pipework?

Test for 30–60 minutes at about 1–1.5× the expected working pressure. Watch the gauge. Any drop means you need to find and fix a leak before closing walls.

Do I need a vent or is an AAV enough?

Direct venting to a stack is best when within distance limits. If that’s not possible, an AAV works well. Keep it above flood level, accessible, and use a quality, approved unit.

Conclusion

Plumbing work runs smooth when you plan routes, set correct falls, support well, and test twice. Small details like clip spacing, trap seals, and slow commissioning prevent leaks and smells. Next steps: 1) Use this checklist on your next job, 2) Log photos and tests, 3) Tighten your scopes and handovers. Platforms such as Donizo can speed proposals, e‑signatures, and invoicing so your site work stays clear and profitable. Keep it simple, be thorough, and your call‑backs will drop.