In Markham, groundwater questions are usually sewer questions. The City's sewer use by-law does not let foundation drains connect to the sanitary system and allows dewatering water into City sewers only with written approval, so most development needs a hydrogeologist to show how much groundwater a site will produce and where it can go. A hydrogeological study in Markham follows York Region's shared terms of reference.
What this means for your project in Markham
- Most Markham projects that need a hydrogeologist go below the water table: underground garages, deep basements and sewer trenches. The study supports the planning application and, later, the request to pump water into a City sewer.
- The City of Markham approves discharge to its sewers first; York Region follows where Regional sewers receive the water. Toronto and Region Conservation Authority reviews effects on streams and wetlands.
- Foundation drains cannot connect to the sanitary sewer, and dewatering water normally goes to the storm sewer, so it has to meet storm sewer limits.
- The local factor most likely to affect scope and cost: groundwater quality. Water that does not meet the storm sewer limits has to be treated before discharge, and the by-law does not allow dilution.
Markham groundwater data
Calculated from public provincial datasets for City of Markham. Each value names its source; links are under Sources at the end of the page.
| Median depth of wells with a water level | 30.5 m (2,465 records reporting depth and water level) |
|---|---|
| Median static water level | 7.6 m below ground (2,465 records reporting depth and water level) |
| Records reaching bedrock | 4.6% of all records with a depth |
| Well records | 10,024 records (all types) |
| Active Permits to Take Water | 22 permits; largest purpose categories: Construction 8, Commercial 7, Dewatering 2 |
| Active construction and dewatering permits | 11 of 22 active Permits to Take Water |
| Conservation authority | Toronto and Region Conservation Authority (100% of area) |
| Provincial plan areas | Oak Ridges Moraine 2.6%; Greenbelt 27.1% of area |
| Sewer discharge | Dewatering water may go to a City storm sewer only with written City approval (By-law 2014-71, s. 4.2); sanitary discharge only in limited cases (City of Markham) |
Source: Well Records (Water Well Information System), MECP (WWIS_2026a), retrieved 2026-10-14.
Source: Permit to Take Water, MECP (PermitsToTakeWater_26-01), retrieved 2026-10-14.
Source: Conservation Authority Administrative Area, Ontario GeoHub, retrieved 2026-10-14.
Source: Oak Ridges Moraine (ORM) Planning Area, Ontario GeoHub; Greenbelt Outer Boundary, Ontario GeoHub; Niagara Escarpment Plan Boundary, Ontario GeoHub; retrieved 2026-10-14.
Figures count records inside the municipal boundary that report a value; well locations and values are as submitted by well contractors, and MECP notes inaccuracies exist. How these figures are calculated.
Construction drives water taking in Markham: 11 of its 22 active Permits to Take Water cover construction or dewatering, before counting the smaller jobs that register on the EASR instead. Groundwater in the well records typically sits 7.6 m down, shallow enough to meet an underground garage, though only monitoring on the site itself can say where it is under a particular building.
What Markham's sewer use by-law means for a building
Sewer Use By-law 2014-71 governs connections to City sewers and the discharge of sewage, storm water and land drainage in Markham's serviced area. For groundwater it sets four rules that shape hydrogeological work on almost every development site:
| Rule | What it means for the study |
|---|---|
| No groundwater drainage to the sanitary system (s. 19.12 A) | Long-term foundation drainage has to go to the storm system or be avoided with a watertight design, so the study must estimate long-term groundwater flow |
| Foundation drains to the City's Engineering Design Criteria (s. 19.12 C) | The design team needs the hydrogeologist's groundwater levels and flow estimates to size and justify the system |
| Dewatering water to storm sewers only with written approval (s. 4.2) | Construction dewatering needs a discharge plan, volumes and water quality, plus the Permit to Take Water where one is required |
| No dilution (s. 5.1) | Water that exceeds the storm sewer limits must be treated, so baseline water quality sampling decides whether treatment is in the budget |
Sanitary sewers are a last resort. The City may approve a temporary dewatering discharge to a sanitary sewer only in an emergency, for a proposed building with no adjacent storm sewer, or for an existing building with no storm connection, and it can attach conditions such as compensation for extra maintenance of the sewage works.
City approval, then York Region
Markham is a secondary approval municipality under York Region's Sewer Use Bylaw No. 2021-102. You apply to the City first; where the water reaches Regional infrastructure indirectly, the Region issues its dewatering discharge approval after it receives the City's. The Region says its review takes up to six weeks after a complete package, that extension requests must arrive at least six weeks before the approval expires, and that expired approvals cannot be extended. Build both timelines into the construction schedule.
Costs follow the water. York Region charges no application or amendment fee for secondary approvals, but it charges a volumetric fee for dewatering water sent to the sanitary sewer and passes on the laboratory cost of samples its own staff take from the site. Markham's by-law also allows the City to charge an application fee for reviewing a discharge request. A hydrogeological estimate of daily and total volumes is therefore part of the construction budget, not only the approval file.
The report that supports the development application follows York Region's shared hydrogeological terms of reference, used by all nine York municipalities with local additions set at pre-consultation. Our Vaughan page covers those terms of reference in detail: four-season monitoring, private well surveys where needed, settlement assessment and the possibility of a peer review at the applicant's cost.
Getting groundwater quality right early
Because Markham sends dewatering water to storm sewers and does not allow dilution, the water quality results in the hydrogeological report carry real cost. A sample that exceeds a storm sewer limit means a treatment system, more sampling during construction, or a different foundation design. Sampling the monitoring wells for the full storm sewer parameter list during the hydrogeological study, rather than after the contractor is mobilized, gives the owner time to price treatment or change the design.
Hydrogeological study cost in Markham
| Study | Starting point | Full span |
|---|---|---|
| Dewatering assessment and EASR reports | $9,000 – $14,000 | $9,000 – $62,500 |
| Groundwater discharge and drainage permits | $3,500 – $6,000 | $3,500 – $15,500 |
| Development groundwater study | $12,000 – $18,000 | $12,000 – $150,000 |
| Long-term Permit to Take Water | $12,000 – $20,000 | $5,500 – $31,000 |
These are indicative ranges based on typical scopes, the same province-wide ranges the estimator uses, not prices specific to Markham. Locally, the work is reviewed by the City of Markham, York Region and Toronto and Region Conservation Authority and, for water takings, the ministry, and the scope they ask for is what moves a quote. Daily dewatering volumes drive both the discharge approval work and the Region's volumetric fee for water sent to the sanitary sewer. Excludes well drilling, government application fees and HST. See typical study costs across Ontario for the full breakdown.
Projects that need a hydrogeological study in Markham
- Buildings with underground parking. A hydrogeological report under the York terms of reference, construction dewatering approvals from the City and Region, and a long-term foundation drainage design that keeps groundwater out of the sanitary system.
- Subdivisions. Groundwater levels for foundation and servicing design, water balance where TRCA or the City asks for it, and dewatering for sewer trenches.
- Sewer, watermain and road projects. Trench dewatering that discharges to City storm sewers needs the same written approval as building sites.
Working with a hydrogeologist in Markham
Markham's approvals hinge on where pumped water goes. The City issues the first dewatering approval and York Region a secondary one; the Region charges no application fee for secondary approvals but does charge a volumetric fee for water sent to the sanitary sewer and passes on the cost of its own samples. Ask for the hydrogeological assessment in Markham to estimate daily discharge and test water quality early, since those numbers drive both the permit and the fee. Foundation drains cannot connect to the sanitary system, so permanent drainage belongs in the same conversation. The geoscientist or engineer estimating Markham discharge volumes can be checked on the PGO public register search or the PEO licence holder search.
Contractors in Markham can pair the City and Region approvals with the EASR dewatering registration steps.
Markham questions
Can a Markham building connect its foundation drains to the sanitary sewer?
No: section 19.12 of Markham's Sewer Use By-law 2014-71 says no direct or indirect connection between a groundwater drainage system and the private sanitary drainage system is permitted. Foundation drains have to be designed to the City's latest Engineering Design Criteria, and the owner installs and maintains them at their own expense.
Where can construction dewatering water go in Markham?
Normally to a storm sewer or land drainage works, and only with the City's prior written approval under section 4.2 of the by-law. Discharge to a sanitary sewer is allowed only by special approval in limited cases: an emergency, a proposed building with no storm sewer next to it, or an existing building with no storm connection.
What goes to the City with a dewatering discharge request?
Section 4.2 lists the reason for the discharge, the volume, the location of the water source, the location where the water is discharged from, the discharge plan, a copy of the Permit to Take Water where one is required, approvals from other agencies where applicable, and the application fee. The City can also ask for plans, reports, studies and analytical results.
Does York Region also have to approve the discharge?
Where the discharge reaches Regional sewers indirectly, yes. Markham is one of four municipalities where York Region's dewatering approval is "secondary": the City issues its approval first, and the Region issues its own dewatering discharge approval only after receiving the City's permit.
Can we dilute groundwater to meet the storm sewer limits?
No: section 5.1 of the by-law prohibits adding water to a discharge for the purpose of meeting the limits. If dewatering water exceeds the storm sewer limits in Table 2 of Schedule A, it has to be treated, not diluted.
Which conservation authority reviews hydrogeology in Markham?
Toronto and Region Conservation Authority covers all of Markham in the provincial boundary data. About 27.1% of the city is inside the Greenbelt outer boundary and 2.6% is in the Oak Ridges Moraine planning area, so most Markham sites deal with TRCA and City rules rather than provincial plan policies.
Studies for Markham sites
- Construction Dewatering Assessment
Groundwater inflow estimates and dewatering rates for excavations, basements and servicing trenches.
- Groundwater Discharge Permits & Foundation Drainage
Approvals for discharging pumped groundwater to municipal sewers, during construction and over the long term.
- Development Hydrogeological Study
Groundwater assessments that support subdivision, site plan and zoning applications.
- Permit to Take Water & EASR
Work out whether a water taking needs an EASR registration or a Permit to Take Water.
- Hydrogeological study cost guide
Ranges for every study type, side by side.
Near Markham
Sources
- Sewer Use By-law 2014-71 (opens in a new tab), City of Markham.
- Well Records: Water Well Information System (WWIS_2026a) and county Well Record Data Reports (WW_Reports_2026a) (opens in a new tab), Government of Ontario (MECP), Ontario Data Catalogue.
- Permit to Take Water dataset (PermitsToTakeWater_26-01) (opens in a new tab), Government of Ontario (MECP), Ontario Data Catalogue.
- Conservation Authority Administrative Area (opens in a new tab), Ontario GeoHub.
- Oak Ridges Moraine (ORM) Planning Area (opens in a new tab), Ontario GeoHub.
- Greenbelt Outer Boundary (opens in a new tab), Ontario GeoHub.
- Niagara Escarpment Plan Boundary (opens in a new tab), Ontario GeoHub.
- Sewer Use Permits: Temporary Dewatering Discharge Program (Sewer Use Bylaw No. 2021-102) (opens in a new tab), York Region.
- Terms of Reference: Hydrogeological Report (Development Application Supporting Studies, June 2024) (opens in a new tab), York Region.
- Public Register (registered members) (opens in a new tab), Professional Geoscientists Ontario.
- Search for licence holders and engineering interns (opens in a new tab), Professional Engineers Ontario.
- Municipal Boundary - Lower and Single Tier (opens in a new tab), Ontario GeoHub.
- OHN Waterbody, 2M generalized layer (provincial hydrography dataset) (opens in a new tab), Ontario GeoHub.
- O. Reg. 63/16: Registrations under Part II.2 of the Act - Water Taking (consolidated to e-Laws currency date October 9, 2026) (opens in a new tab), Government of Ontario (e-Laws).