Water can reach a house from the ground around the foundation and through the pipes that carry waste and rain away. On a lot near a creek or on a slope, the water outside the house can also limit what you are allowed to build. This chapter explains which parts of that system belong to the owner, how to confirm what a house is connected to, and which questions to ask for a lot near a watercourse.
It is part of the property checks guide. The home inspection chapter explains why buried pipes sit outside a visual inspection, and the title chapter explains the rights of way that may hold city pipes.
Three kinds of evidence about water and services
What you can observe: water stains at the base of basement walls, a sump or pump, cracked paving that slopes toward the house, downspouts that run into the ground, a creek or ditch nearby, and a steep bank at the back of the lot.
What a document proves: city records about the service connections at the property line, a camera inspection report on the private pipes, invoices for drain work, the city's maps of floodplains and watercourse setbacks, and any covenant on title.
What needs a professional: where the drains actually go, the condition of the buried pipes, how groundwater moves on the lot, and whether a slope is stable. A plumber or drainage specialist, a geotechnical engineer and an environmental professional each answer different parts.
Who owns which pipe
A house has several buried connections. The sanitary sewer carries waste from toilets, sinks and appliances. The storm system carries rain and groundwater. The water service brings drinking water in.
Coquitlam's sewer page describes the two sewer systems. Storm sewers and catch basins collect rainwater and melting snow from roads, roofs, downspouts and building foundation drains, then empty directly to waterways. Sanitary sewers carry wastewater to a regional treatment plant on Annacis Island.
Responsibility is split at the property line. Port Coquitlam's risk management page says the private water service, from the property line to the house, is the owner's responsibility. For sewer backups, it says it is the owner's responsibility to find where a blockage is, on private or public land, and that a plumber should be called to find it. Coquitlam's inflow and infiltration page says nearly 50 percent of the city's sanitary sewer system is on private property and is privately owned.
So a buyer takes on the private pipes along with the house. Their age and condition are part of what you are buying.
Perimeter drains and where they go
A perimeter drain, also called a foundation drain, is a pipe laid around the base of the foundation to collect groundwater. It is buried and out of sight.
Coquitlam's sewer page names building foundation drains among the sources that storm sewers collect. Its inflow and infiltration page explains why the connection matters. Rainwater and groundwater that enter the sanitary system through damaged pipes or wrong connections use up space meant for wastewater, which can cause backups into homes and overflows to the environment. The page asks owners to check that basement and foundation drains, gutters and outside drains are not connected to the sanitary sewer.
A home inspection is visual, so a buried drain sits outside what the inspector can see. A drainage specialist can camera inspect it, find where it discharges, and report on its condition. If the house has had water in the basement, ask the seller what was done, by whom, and whether there are invoices.
Confirming the connections for a Coquitlam address
Coquitlam's building and construction page says you can view records about the sanitary, storm or water service at the property line at the Engineering and Public Works customer service counter at City Hall. Its building permits FAQ adds that you can visit that counter or email staff to locate a service connection, and that staff can help if you cannot find it.
The same FAQ says most homes have a main water shut off where the water connection enters the house, usually in the basement or crawlspace. Find it during a viewing or the inspection.
Some properties are not on the city sanitary sewer. Coquitlam's sewer page includes advice for septic system owners: have the system inspected every one to three years and pump the tank as needed, generally every 18 to 36 months. If the house you are buying has a septic system, ask for its inspection and pumping records.
Coquitlam also runs a sanitary connection grant program. It funds 25 percent of the cost of replacing the private sanitary connection between the property line and the house, up to $2,000. As read on 30 September 2026, the city describes it as a pilot, with the first phase focused on properties fronting a portion of Chapman Avenue in the Stoney Creek catchment. The same page reports that a camera inspection of laterals near Chapman Avenue in early 2022 found deficiencies in more than 40 percent of the connections inspected.
Confirming the connections for a Port Coquitlam address
Port Coquitlam's single-family permit page says information on the location and condition of water, storm and sanitary sewer services is available from the Engineering and Operations Department. It adds that the same information can be found on PoCoMAP, the city's online map. The page also says PoCoMAP shows zoning, land use and flood construction levels.
Start with PoCoMAP for the address. Then ask Engineering and Operations about anything the map does not answer.
| Question | Where to ask in Coquitlam | Where to ask in Port Coquitlam |
|---|---|---|
| Where are the service connections? | Engineering and Public Works counter, City Hall | PoCoMAP, then Engineering and Operations |
| Is the lot in a floodplain? | QtheMap, then Building Permits Division | PoCoMAP flood construction levels |
| Is there a watercourse setback? | QtheMap environment layers | Watercourse development permit page |
| What condition are the private pipes in? | A plumber or drainage specialist | A plumber or drainage specialist |
Questions to put to the seller
Ask the seller, in writing and through your real estate professional, a short set of questions about water and services. Has water ever entered the basement or crawlspace, and when? Has the perimeter drain been cleaned, inspected or replaced, and by whom? Has the sewer line been camera inspected, and is there a report or video? Have there been sewer backups, and where was the blockage found? Is there a sump pump, and what does it discharge to? Has the house ever used a septic system?
Some of these questions also appear on the seller's disclosure statement, which the journal article on the property disclosure statement explains. Keep each answer with the date and the name of the person who gave it. A written answer is a statement you can check. An invoice or a camera report is evidence you can hand to a drainage specialist. Where the seller does not know, record that too, and plan your own inspection before the subject deadline.
A lot near a creek or on a floodplain
Coquitlam's watercourse setbacks page explains the rules for land near streams. The city applies a Streamside Protection and Enhancement Area, a 30 metre zone on each side of a watercourse measured from the top of the ravine bank, with a 15 metre zone on a few watercourses. That area restricts development and the removal of trees or vegetation. The page lists other setbacks that may also apply: setbacks from the protected area for rear and side yards, setbacks in registered covenants, flood protection and slope control rules in the zoning bylaw, and setbacks from geotechnical assessments. The city's QtheMap shows these layers.
Coquitlam's building permits FAQ says QtheMap identifies lots that may be affected by high water levels, and recommends contacting the Building Permits Division for a final determination. It defines the flood construction level as the lowest elevation at which livable floor space can be built.
In Port Coquitlam, the single-family permit page says a new or revised floodplain covenant may be required if the site is on a floodplain, and that development within 50 metres of a watercourse should be checked against the city's watercourse development permit rules.
For a buyer, these rules matter most if you plan to add a suite, a garage or an addition later. Check them before you remove subjects, and read the land and zoning guide for what the zoning allows.
A lot on a slope
On a sloping lot, ask where surface water goes in heavy rain and whether the house has had water enter. Look at retaining walls. Coquitlam's building permits FAQ says a retaining wall over 1.2 metres needs a building permit and must be designed by a professional engineer, so ask for the permit and the engineer's documents for any tall wall. The permits chapter explains how to request them. Ask the seller whether any work was done on the slope, such as new drains, wall repairs or regrading, and whether an engineer was involved. Questions about slope stability belong with a geotechnical engineer, who can also say whether the lot needs monitoring or further study before you commit.