Cost of Replumbing a House in London: Full Price Guide for 2025
Replumbing — replacing the hot and cold water supply pipework and associated fittings throughout a property — is a major investment but often essential in older London properties with outdated plumbing systems.
When Is Replumbing Needed?
Full replumbing is needed when:
- The property has lead water supply pipes (common in pre-1970s properties, particularly Victorian). Lead pipes should always be replaced
- The copper pipework is original pre-1960s and showing corrosion or has had repeated repair patches
- The boiler is being replaced with a system that requires different pipework configuration (e.g. converting from a vented gravity-fed system to an unvented pressurised system)
- A renovation is creating a new bathroom layout, new kitchen configuration, or additional en-suites that require new supply and waste routing
What Does Replumbing Involve?
A full replumb replaces:
- Hot and cold water supply pipes throughout the property
- The boiler and heating controls (often done simultaneously)
- Radiator pipework and radiators
- Waste and soil pipework where replacing
- All associated valves, stopcocks, and connections
Supply pipework is typically run in 15mm or 22mm copper or modern plastic (MLCP or CPVC) in chases, under floors, or in service voids. As with electrical rewires, the work is significantly less disruptive and less expensive when done during a renovation with walls and floors already opened up.
Typical Replumbing Costs in London
| Property size | Estimated cost (supply & fix) |
|---|---|
| 1-bedroom flat (complete replumb) | £3,000–£5,500 |
| 2-bedroom flat or small terrace | £5,000–£9,000 |
| 3-bedroom terrace | £8,000–£14,000 |
| 4-bedroom semi | £12,000–£20,000 |
| 5+ bedroom detached | £18,000–£30,000+ |
These figures include labour, fittings, and pipe materials but typically exclude boiler replacement (separately priced) and bathroom/kitchen sanitaryware.
Important cost driver: Lead pipe replacement from the street to the property boundary — the supply pipe from the water main to the stop cock at the external wall — may be the responsibility of the water authority (Thames Water in most of London) and can sometimes be replaced at reduced or no cost. Check with your water authority.
Hot Water System Considerations
Victorian properties typically have vented (gravity-fed) hot water systems with a cold water tank in the loft and a hot water cylinder. Modern renovations often convert to:
- Combi boiler: No hot water cylinder or cold water tank required. Works well for smaller properties with moderate hot water demand
- Unvented (pressurised) hot water cylinder: Mains-pressure hot water without a cold water tank. Better for larger properties with multiple bathrooms
The system conversion choice affects the replumbing scope and cost.
RCB Design & Build
RCB Design & Build delivers full replumbing as part of comprehensive renovation programmes — managing plumbing works in the correct sequence with structural, electrical, and finishing trades.