Drains and sewers: the complete guide

From trap to soil stack: the drains inside your home

Every fixture starts with a trap, also called a siphon. That curved section of pipe holds a small amount of water that keeps sewer smells out. From the trap a branch pipe runs at a slight fall to a collector pipe or straight to the soil stack: the vertical pipe that carries water down from the upper floors. In a family home this is often a single 110 mm soil stack, which continues at the top to above the roof for ventilation.

At the bottom of the soil stack the pipe bends into the horizontal underground drain, which runs out through the crawl space or under the ground floor. At that point many homes have an access fitting: a fitting with a removable cover that lets an engineer reach the pipe without breaking anything open. The kitchen and washing machine often connect to this horizontal section via their own collector pipe too.

Beyond the outside wall: property drainage and boundary

Once the pipe passes the outside wall, we speak of external or property drainage. It runs under the garden, driveway or pavement to the property boundary. In many municipalities there is an inspection chamber or boundary chamber there: a vertical pipe with a cover that gives access to the connection. Downpipes often connect to this section as well, unless the home has been disconnected and rainwater is drained separately or soaks away in the garden.

The section up to the property boundary is usually the responsibility of the homeowner. That includes the pipes under the garden and driveway, which often lie untouched for decades. Exactly where the boundary lies differs per municipality: sometimes the inspection chamber is the dividing point, sometimes the land registry boundary. If in doubt, the municipality can tell you, for example through the municipal sewerage plan or its customer service.

House connection and main sewer: the last few metres

Beyond the property boundary the house connection joins the municipal sewer under the street. That main sewer is usually concrete or PVC and carries the waste water by gravity, with pumping stations where needed, to the wastewater treatment plant. Depending on the neighbourhood it is a combined system, in which rainwater and waste water flow together, or a separate system with two pipes. In the countryside there is often a pressure sewer, where a pump pushes the waste water through a narrow rising main.

Bosmans Rioolservice works on the whole route you are responsible for as an owner: from a blocked trap to the underground drain and house connection. With CCTV surveys, high pressure jetting, unblocking and relining, our 42 certified engineers keep your drains flowing freely. You hear the rate before the engineer drives out, the call-out is from 45 euros and you get a 2-year guarantee on the work. For an emergency, the 24/7 service is ready in all twelve provinces.