When you’re building a new home, getting the drainage right is one of the most important jobs on site. Without proper drainage services, you could face flooding, sewage problems, and expensive repairs later on. This guide explains what new builds need in simple terms.
Why Drainage Matters
Drainage is the system of pipes and channels that carries water away from your building. Poor drainage can cause flooding, damage to foundations, and health hazards from standing water. It can also stop you from getting building regulations approval.
The Two Types of Drainage
Every new build needs two separate drainage systems. Keeping them apart is a legal requirement.
Foul Water Drainage
This carries dirty water from toilets, sinks, baths, showers, washing machines, and dishwashers. All this wastewater travels through underground pipes to either the public sewer or a private system like a septic tank.
Surface Water Drainage
This deals with rainwater from roofs, driveways, and patios. Good water flow away from the building is essential to prevent flooding. Surface water usually goes to a soakaway, watercourse, or storm drain. Solutions like French drains can help manage water on sites where the ground doesn’t absorb water well.
Building Regulations Part H
In the UK, all drainage services on new builds must meet Building Regulations Part H. Here’s what it covers:
| Section | What It Covers |
|---|---|
| H1 | Foul water drainage from your building to the sewer |
| H2 | Septic tanks and cesspools |
| H3 | Rainwater drainage, gutters, and surface water |
| H4 | Building over existing sewers |
| H5 | Keeping foul and surface water separate |
| H6 | Bin storage and waste collection |
For detailed guidance, the Planning Portal’s page on drainage and Building Regulations is an excellent resource.
Key Drainage Services for New Builds
Survey and Planning
Before any pipes go in, you need a proper survey. This checks where existing drains are, tests whether the ground can absorb water, and plans the best route for new drainage.
Underground Installation
This includes laying pipes at the correct depth and angle, building inspection chambers for maintenance, and connecting to the public sewer. The right gradient ensures good water flow so nothing gets stuck in the pipes.
Above-Ground Work
Inside and around the building, you’ll need soil pipes, waste pipes, ventilation through the roof, and gutters with downpipes for rainwater.
Testing
All drainage must be tested before it’s covered up. Building Control checks for leaks, proper gradients, correct pipe sizes, and access points in the right places.
Common Mistakes to Avoid
Wrong pipe gradients – Pipes need the right slope. Too flat and water won’t flow. Too steep and solids get left behind.
Skipping inspection – Never cover drainage before Building Control checks it. You might have to dig it all up again.
Mixing systems – Connecting foul and surface water is against regulations and can overload sewers during heavy rain.
Forgetting access – You need inspection chambers at key points so the system can be cleared if it blocks.
Choosing the Right Contractor
When selecting a team for your new build projects, look for experience with Building Regulations Part H, proper insurance, good references, and clear communication about costs and timelines. A reliable contractor works closely with Building Control to make sure everything passes the first time.
Final Thoughts
Drainage might be hidden underground, but it’s one of the most critical parts of any new build. Getting it right from the start saves money and prevents problems for years to come. Whether you’re planning a single home or a larger development, investing in quality drainage services is always worthwhile.
