Residential drainage for Christchurch homes.

Foul water and stormwater are two separate systems

Every house has two sets of drains. Foul water, also called wastewater, comes from toilets, showers, basins, the kitchen and the laundry, and goes to the sewer. Stormwater comes off the roof and hard surfaces and goes to the stormwater system, the kerb, or soakage. The two are kept apart from start to finish.

On a new build we lay both. Foul drains are certified work and are signed off by a certifying drainlayer. Stormwater on an existing section, such as a soggy lawn or a driveway that floods the garage, has its own page under stormwater and yard drainage.

Getting the fall right

A drain works on gravity, so it has to slope the right amount. Too little fall and solids settle in the pipe. Uneven fall and a dip forms where water sits. Either way the line drains on day one and silts up over the following years.

So the levels are set before the trench is dug, the pipe is bedded so it cannot settle, and the fall is checked as each length goes in. It is slower than throwing pipe in a trench and it is why a properly laid drain goes unnoticed for decades.

Working with your builder

A good share of our residential work comes through builders and developers, so we are used to fitting into a build programme. Drainage goes in at set points around the foundations and slab, and it has to be inspected by the council before it is covered over. We book those inspections and keep the trench open until they are passed.

If you are an owner building or extending, the same applies. Tell us where the project is up to and we will work out what needs to happen and when. Replacing a failed drain at an existing house is covered under drain repairs.