When planning any renovation it is easy to get caught up in the design work and overlook the condition of your drainage system. Because most drainage runs behind walls and under floors problems often remain hidden until your build is already underway. Once discovered these issues can halt progress and increase costs.
This guide explains what to check before starting any renovation and outlines the essential renovation drainage requirements set by UK regulations.
Why Drainage Checks Matter in Renovation Projects
Drainage issues cause some of the most disruptive and expensive delays during refurbishments. Renovations often increase the load on your drainage system which exposes weaknesses in older pipework. UK Building Regulations highlight strict standards for drainage design and compliance. You can review these requirements in Approved Document H from the UK Government:
https://www.gov.uk/government/publications/drainage-and-waste-disposal-approved-document-h
Carrying out checks early helps you avoid:
Water damage to new construction
Sewage smells or backflow
Non-compliance with building regulations
Delays caused by hidden defects
Check for Existing Drainage Problems Before You Renovate
Before work begins walk through your property to identify any signs of existing drainage issues.
Slow Drains or Gurgling Noises
These may indicate partial blockages or venting problems which should be investigated with a CCTV drainage survey.
Foul Smells from Drains
Bad odours can be caused by debris or faults in the system. The national register WaterSafe offers guidance on what odours may indicate:
Damp Patches or Mould
Damp areas near drainage runs often point to leaks that must be repaired before you renovate.
Previous Backflow Incidents
If your property has experienced backflow or overflowing drains you may have gradient or soil stack issues that need correcting.
Inspect the Age and Material of Your Pipework
The type and age of your drainage and water supply pipes has a major impact on renovation planning.
Lead Pipes
Many UK homes built before the 1970s still contain lead supply pipes. Lead in drinking water can be harmful which is why the Drinking Water Inspectorate (DWI) advises replacing lead supply pipes wherever found. Renovation is the ideal time to remove lead pipes as groundworks are often already planned. Tiger Utilities provides compliant and safe lead pipe replacement.
Clay, Cast Iron or Pitch Fibre Pipes
These older materials crack, deform or collapse over time. Renovation movements can accelerate failure.
Modern PVC or HDPE Pipes
Although more reliable older installations may not meet current building standards.
Understand Your Property’s Drainage Layout
Before planning your renovation you should understand how your drainage system is arranged.
Identify Routes and Inspection Chambers
Knowing the location of soil stacks, inspection chambers and branch connections helps you understand what can be moved or extended.
Check for Shared Drains
Shared drains are common in terraced and semi-detached homes. They are often the responsibility of the water authority not the homeowner. Ofwat provides guidance on shared drainage responsibilities:
Confirm Whether Foul and Surface Water Systems Are Separate
Modern systems must keep foul and surface water separate. Older combined systems may need correction during renovation.
Renovation Drainage Requirements You Must Follow
UK Building Regulations Part H outlines essential drainage standards. These include:
- Correct gradients for waste pipes
- Suitable pipe diameters for each fixture
- Adequate venting to prevent pressure imbalances
- Access points for cleaning and maintenance
- Minimum separation distances between appliances and soil stacks
You can read the full specification in Approved Document H.
Local Water Authority Notifications
If you are altering water supply connections or installing new appliances, you may need to notify your water company.
Backflow and Waterproofing Protection
Homes with basements or extensions below sewer level may require anti-flood valves or pumped systems.
Why a Professional Drain Survey is Essential
Even if your drainage appears fine a survey provides a clear view of underground conditions.
CCTV Drain Survey
Ideal for locating cracks, intrusions and collapsed pipes.
Water Pressure and Flow Testing
Ensures your supply can support new bathrooms or appliances.
Leak Detection
Prevents hidden moisture damage within new walls and floors.
Lead Pipe Assessment
If lead pipes are present Tiger Utilities can replace them and bring the system up to modern standards.
Drainage Considerations for Different Types of Renovation
New Bathrooms or Ensuites
The layout must meet venting, access and gradient requirements.
Kitchen Renovations
Dishwashers and washing machines need appropriate dedicated drainage.
Loft Conversions and Extensions
Distance from the soil stack determines whether gravity drainage is possible or if a pumped system is needed.
Basement Conversions
These usually require pumped drainage due to their below-ground level.
When to Upgrade or Replace Drainage During Renovation
Upgrading drainage during renovation is often the most economical time. Consider replacement if:
Pipes are ageing or damaged
You plan to add new water appliances
Existing gradients are incorrect
You are replacing lead supply pipes
You are installing greywater or rainwater systems
Common Mistakes Homeowners Make
Blocking or covering access chambers
Ignoring damp patches or minor leaks
Assuming old pipework can handle modern water usage
Forgetting to check shared drainage responsibilities
Leaving lead pipe replacement until after renovation
How Tiger Utilities Can Help
Tiger Utilities provides:
Lead pipe replacement
CCTV drain surveys
Excavation and new drainage installation
Water supply upgrades
Emergency drainage repairs
Book a drainage inspection before your renovation to prevent unnecessary delays and protect your investment.
Take Away Points
Checking your drainage system before starting any renovation project is essential. From identifying pipe materials to meeting regulatory requirements a thorough assessment ensures your renovation runs smoothly and safely. With expert support from Tiger Utilities you can plan with confidence.
