Protecting your project. Avoiding delays. Getting approvals right first time.
When you’re planning an extension or any kind of property reconfiguration in Wales, one of the biggest hidden risks is the presence of shared public sewers. These pipes are owned and maintained by Welsh Water (Dŵr Cymru) — and they are often located exactly where homeowners want to build.
If your project is close to, over, or requires altering one of these public sewers, you will need a Build Over Agreement or a Sewer Diversion Agreement before construction can begin. Failing to secure the correct approval can lead to:
- Delays to your planning or Building Control sign‑off
- Costly redesigns
- Construction being stopped on site
- Problems when selling or remortgaging the property
- Legal action
I help homeowners and small commercial clients navigate this process smoothly, ensuring your project stays compliant and on track.
How I Help
1. Identifying Affected Sewers Early
Using accurate site surveys, drainage plans and on‑site checks, I confirm whether Welsh Water assets run near or beneath your proposed works. Early identification prevents surprises later in the process.
2. Producing the Required Technical Drawings
Welsh Water require clear, precise drawings showing:
- Existing and proposed drainage layouts
- Pipe sizes, depths and materials
- Foundation solutions near sewers
- Any proposed diversions or protection measures
I prepare all drawings to the standard Welsh Water expect, reducing the chance of queries or rejections.
3. Managing the Application Process
I handle the full submission on your behalf, including:
- Completing Welsh Water’s application forms
- Providing all technical documents
- Responding to any follow‑up questions
- Coordinating with your builder or engineer if needed
This keeps the process simple for you and avoids unnecessary delays.
4. Ensuring Compliance During Construction
If Welsh Water require inspections or specific construction methods, I make sure these are clearly communicated and integrated into your build.
Why This Matters More Than Ever
Since the transfer of private sewers to Welsh Water in 2011, thousands of previously unknown shared sewers now fall under their ownership. As a result, more and more extensions require formal approval, even for modest domestic projects.
Getting this right early protects your investment and keeps your project moving.
Start Your Project with Confidence
If you’re planning an extension or reconfiguration and want to avoid delays, I can quickly assess your site and advise whether a Build Over or Sewer Diversion Agreement is required.
Clear guidance. Accurate drawings. Smooth approvals.