How sewers work
Main components
The four main components to the sewer and drainage system related to your home are:
The sewer system collects all sewage and most of the rainwater runoff from buildings and other hard surfaces (roads, parking lots, etc.). These liquids are collected and conveyed through a network of about 2800 km of pipes to the waters surrounding Vancouver in the case of rainwater run-off, or to a sewage treatment plant in the case of sewage.
For the most part, the whole system relies on gravity to collect and convey the water. This means that the need for pumping the water up hill is very limited in Vancouver. Vancouver does have some pumping stations that move the wastewater collected in low lying areas up to large sewers that convey the liquid waste to the treatment plants, but these are kept to a minimum through good design practices. Designing the system to avoid pumping as much as possible results in lower financial and ecological costs.
Most homes drain by gravity too, although some buildings with basements have to pump to get the water up to the sewer main and to protect from flooding.
Property owners are responsible for internal plumbing and the sewer services, which are the pipes that connect the building to the City's sewer system. The City takes care of the sewer infrastructure beyond the property line, which divides private property from the City's property.
Single sewer connection
Separated sewer connection
These diagrams generally illustrate how drainage works in most houses and the way houses are connected to the sewer system. Every house is different - these are intended to give you the general principle. The main difference between the two is that homes built before 1985 typically have a single pipe that connects to the sewer system, while homes built after 1985 typically have two pipes that connect to the system.
As illustrated, the two pipe system results in the separation of sewage from rainwater runoff. This enhances environmental performance of the whole sewer system and eventually every building in Vancouver will be required to have a two-pipe system.
For further description of sewer separation see the sewer separation page.
Downspouts or Roof Drains
Downspouts or roof drains collect rainwater that falls on the roof. The rainwater on the roof collects in eaves troughs and is directed to a downspout or roof rain located against the siding of the home. Downspouts are attached to 3 to 4" (75mm,100mm) diameter piping typically buried two to three feet below the ground. The water flows through these pipes to a sump or concrete collection chamber located either inside or outside of the home.
Some older homes do not have piping to intercept water flowing from the roof. This means the downspouts may connect directly into the drain-tile or percolate directly into the ground itself. In some cases, flow of storm-water is directed to a drainage or rock pit.
Drain-tile or Footing Drains
The terms drain-tile, footing drains, and weeping tile all refer to piping that is placed around the home's perimeter at the footings of the foundation. Drain-tile is designed to collect groundwater that seeps through the earth during rainfall. The groundwater trickles to the drain-tile entering the piping at the joints or through perforations in the pipe.
From time to time drain-tile can break or become clogged with debris. Downspouts connected directly to the drain-tile can carry sediment and rotting leaves that have landed on the roof. Soil can also build up in the drain-tile. The consequence of non functioning drain-tiles might be water leaching or seeping through the porous concrete foundation or leaving a damp mark on the basement floor or foundation wall. Often a repair to the section of tiles or a flushing will alleviate the problem. Sometimes, replacement of the piping is required.
The depth of the drain-tile correlates to the depth of the basement floor. For example, if the basement is four feet or 1.2 metres below the ground level, then the drain-tile would quite likely be 12" to 18" or 30 to 45 cm below the basement floor depth.
The sump
Flow from drain-tiles and downspouts link up at a concrete square or cylindrical chamber referred to as a sump. The flow drains into the sump via two inlets and then exits from an outlet pipe after the water level in the sump reaches a certain elevation. The outlet pipe has a 90 degree bend referred to as a goose neck. On the downstream side of the goose neck, is a backwater valve designed to stop sanitary flow from backing up into the sump. If the plumbing system of the home considered combined, meaning both rainwater run-off and sewage flow into one pipe the outlet pipe from the sump will connect to the sewer main several feet or metres downstream of the sump.
Check sumps annually
Even in dry weather, there should be water in the sump at a level of just above the "goose neck". The water acts as a lock or barrier for sewer gases which sometimes vent from the sewer main back to the home. If you ever smell a rotten egg like sewer smell in your basement, check the level of water in your sump to see if there is an air gap between the surface of water and the goose neck. Fill the sump with water from a hose and replenish the level until it begins draining out the sump outlet. Backwater valves should be checked annually to see whether they are functioning properly. Unscrew the top cap of the backwater valve to insure the flapper is correctly seated and can shut in cases of backflow from the main sewer-line. Summertime is a good time to inspect your sump.
Sumps can be located in a number of places depending on the design and age of the home. Sumps are often in one of the following places: inside the basement, outside under the front steps, porches, or in the yard. Sometimes sumps are covered over with flooring and cannot be easily located inside the home. Some older homes do not have sumps.
If you cannot find your sump, the plumbing inspections branch may have a sump permit on hand which sometimes indicates the location. Contact the inspections branch at 604-873-7601 and find out how to initiate a search for a sump permit for your address. There may be a small charge associated for this service.
The drawing above is intended for general information only. Enquiries regarding sump specifications, placement, and regulations should be directed to the Plumbing Inspections call: 3-1-1
Sewer Service and Sewer Main
The pipes that collect the rainwater runoff and sewage from your house and convey it to the sewer main are referred to by several names. Technically these pipes are called the building sewers, most people refer to them as the connection or services. The portion of the pipes that run from your home to the property-line are often referred to as the private-side connection. The pipes that run from the property line to the sewer main are often referred to as the city-side connection.
Maintenance of the private-side connection is the responsibility of the property owner. However the City has a prevention program that helps prevent connections (private-side and city-side) from becoming chronic problems.
