When Should You Reroute Waste Pipes During a Renovation?

If you’re planning a kitchen, bathroom, or utility renovation, chances are you’ve wondered whether the existing waste pipe layout will still work — or whether it needs to change.

At EPM, we’re often brought in across Exeter, Teignmouth, Exmouth, and the South Hams to advise on exactly this during home upgrades.

Here’s when you should consider rerouting waste pipework, and what to think about before the floorboards come up or the tiles go on.

What Are Waste Pipes?

Waste pipes carry used water away from:

• Sinks

• Baths and showers

• Washing machines and dishwashers

They’re smaller than soil pipes (usually 32mm to 50mm) and need to maintain a proper fall (gradient) to work properly.

When Should You Reroute Them?

1. You’re Moving Appliances or Fixtures

If you’re relocating a washing machine, sink, or bath — even by a metre or two — it’s often best to reroute the waste pipe to ensure the fall is correct and the pipe run is efficient.

2. Existing Pipe Runs Are Poorly Installed

We frequently uncover:

• Waste pipes with no fall (or even sloping the wrong way)

• Long horizontal runs that back up

• Pipes running uphill into traps

• Connections made with the wrong fittings

If your current pipework has caused smells or slow drainage, now is the time to fix it properly.

3. The System Is Too Noisy or Exposed

Noisy gurgling waste pipes in stud walls or boxed-in pipework behind toilets is common — especially in older homes.

Rerouting or upgrading with better brackets, insulation, and gradients can reduce sound and improve performance.

4. You’re Upgrading to Modern Fixtures

Newer appliances often have different waste sizes, flow rates, or pressure discharge — especially pumped showers or high-flow baths. Old 32mm pipework may not be up to the job.

What If I Don’t?

Reusing existing waste pipe runs might save time, but there are risks:

• Water backing up or slow drainage

• Pipework coming loose behind new cabinets

• Leaks inside walls or floors

• Fittings that don’t meet Building Regulations

A proper inspection beforehand can save a lot of hassle later.

How We Can Help

At EPM, we work alongside builders, designers, and homeowners to:

• Assess existing waste layouts

• Recommend the most efficient and compliant reroute

• Carry out the installation and pressure testing

• Ensure every fall, joint, and connection meets spec

We’re known for our fast, tidy work across Devon — and for getting it right the first time.

What It Might Cost

Typical rerouting costs vary depending on access and run length:

• Minor reroute (underfloor): £150–£300

• Full kitchen/bathroom rework: £400–£900

• Wall chases or concealed rerouting: Estimated after survey

We’ll always provide a full estimate before lifting a floorboard.

Final Word from EPM

If you’re already renovating — don’t let bad pipework spoil the finish.
Get it right behind the walls and under the floors, and everything else just works better.