Build-Over Agreement (Water Company Sewer)
PremiumIf a public sewer runs within 3m of your extension, you need written consent from your water company before breaking ground. Here's how to check, apply, and what happens if you don't.
Your water company has the statutory right to demolish any structure built over their sewer without permission. Not "might seek an injunction." Not "could take you to court." Demolish. And they don't have to compensate you.
That's the legal position under the Water Industry Act 1991. It's not hypothetical. Homeowners have had extensions pulled apart to access blocked or cracked sewers. The fix is simple, but it has to happen before construction starts.
A build-over agreement must be obtained before your groundworker breaks ground. Apply at the same time as your building control full plans submission, not when the builder is ready to dig. If a public sewer runs under or near your extension footprint, check the sewer map before finalising your extension design. It affects foundation design, and possibly the entire extension layout. The drainage leaf covers the wider drainage system and soakaway requirements for your extension.
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