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Guide · Drainage

Yard drainage: slopes, downspouts, French drain, catch basin and dry well

Most water problems are solved at the surface: extended downspouts and ground that slopes away from the house. When more is needed, this guide explains the French drain, the catch basin and the dry well, with the minimum fall, the materials and the rule against making runoff onto the neighbour worse.
Level : IntermediateDraftReviewed October 10, 2026Next review: April 10, 202721 sources
Ava paver driveway in a hexagon pattern, image from Rinox's article on permeable paving
Photo: Rinox
Draft.This guide is a draft. It has not yet been reviewed by an experienced installer or an engineer. Quantities and times come from the engine; the text may still change.
In this guide

Your project

The guide's typical project: 20 m (66 ft) of French drain and 2 downspouts. The quantities below come from the calculator and drive every time in this guide.
MaterialQuantity
20 mm clear stone4.52 t
Non-woven geotextile33 m² (355.2 sq ft)
100 mm perforated drain and solid outlet pipe24 m (78.7 ft)
Catch basin with gratenot needed for this project
Downspout extensions3 m (9.8 ft)
Splash pads2
Computed for: Quebec (province)
Estimated total working time
Beginner
49 person-h30 to 93 person-h
Intermediate
33 person-h22 to 56 person-h

The total and each step's time come from the same calculation as the estimator: the steps plus machine learning add up to the total. Planning steps (locate request, permits) keep the guide's fixed time.

Customize these quantitiesThis project's cost
Phase 1 · Assessment

Understand where the water goes

Before digging a drain, watch where water runs during a heavy rain and where it sits. Often it is enough to extend the downspouts away from the foundation and give the ground a slope that takes water away from the house.

  • Next to the foundation, the ground must fall away: the APCHQ plans 10% over the first 2 m at backfill, and the Calgary guide at least 4% over 1.2 m.
  • A lawn or a swale needs at least 2% of fall to drain.
  • Lower land must receive the water that flows naturally from higher land, but you may not make your neighbour's situation worse by concentrating or redirecting water toward them (Civil Code, art. 979).

Then choose the structure: extended downspout, swale, French drain, catch basin or dry well. The calculator gives the quantities for each.

  1. 01Watch the water and measure the slopes[1, 2, 3, 4]

    1. During a heavy rain, go out with an umbrella and note where water runs, where it pools and where it comes from (roof, driveway, neighbouring land).
    2. Find each downspout and where its water ends up.
    3. Measure the slope next to the foundation: set a level 1.2 m board against the wall and measure the gap under its free end.
    4. Note the direction of flow at the property lines.
    5. Make a sketch with this information.

    Done when : You have a sketch of the yard with the downspouts, the low spots, the direction of flow and the slopes measured next to the foundation.

  2. 02Choose the structure, the route and the outlet[2, 4, 5, 6]

    1. Start with the downspouts and the ground slope; add a drain only if water still sits.
    2. For a French drain or a catch basin, choose the outlet: to daylight on your land, into a dry well, or to the storm system only where the municipality allows it.
    3. Measure the height difference between the start and the outlet: you need at least 1% of fall over the full length, never less than 0.5%.
    4. Keep the outlet at least 2 m from the property line and from public infrastructure, and do not aim it at the neighbour.
    5. For a dry well, plan an infiltration test and a good distance from the foundation (we plan at least 3 m, an estimate).

    Done when : The start, route and outlet are chosen, the height difference gives at least 1% of fall over the full length, and the outlet stays on your land at least 2 m from the line.

    Safety : Never look into the rotating laser beam or aim it at anyone's eyes. Set the tripod on firm ground, out of the way of traffic.

Phase 2 · Permits and locates

Rules, permits and locates

A yard drain, a French drain or a swale on your land is not plumbing under the Construction Code: the plumbing chapter excludes piping not attached to a building and foundation drains. A connection to the building drain or the municipal sewer needs a plumber and, generally, a permit. Municipalities also have their own rules on downspouts and rainwater. Before you dig, file your Info-Excavation request.

  1. 01Check municipal rules and plumbing status[4, 7, 8]

    1. Ask your municipality for its rules on downspouts (disconnection from the foundation drain), rainwater management and connections to the storm system.
    2. A yard drain not connected to the house is not plumbing. If the outlet goes to the municipal system or the building drain, hire a plumber who is a CMMTQ member and get the permit.
    3. For a dry well, ask whether the municipality regulates it (distance, soil, connected surfaces).
    4. Keep the answers in writing.

    Done when : You have the municipal rules affecting your outlet in writing, and any required permit is issued.

  2. 02File the locate request[4, 9]

    1. File the free Info-Excavation request at least 4 business days before digging, for the whole drain route and the location of any catch basin or dry well.
    2. Write down the request number and its end date (180 days at most).
    3. Wait for marks or clearances from every owner notified.
    4. Also find your private lines along the route: garage wires, lighting, irrigation.

    Done when : You have a valid request number and all marks or clearances along the route before digging.

Phase 3 · Excavation

Dig the trench on a fall

A French drain is a trench somewhat wider than the pipe, deep enough to hold a stone bed, the pipe and a stone cover. Its bottom must fall continuously toward the outlet: at least 1%, never less than 0.5%. A dip or a back-fall holds water and eventually clogs the drain. The calculator gives the width, the volume to dig and the spoil.

  1. 01Check that the soil absorbs (dry well)[2, 4, 6]

    This step applies only to a dry well.

    1. Once the locate marks are in, dig a test hole where the well will go, to its planned depth.
    2. Note the soil you find: sand and gravel absorb well; clay and silt absorb poorly.
    3. Fill the hole with water, let it drain, fill it again and measure how far the level drops over a set time, using the method your municipality or a professional asks for.
    4. If the water barely drops, give up on the dry well and choose another outlet.

    Done when : You have written down the soil and the water level drop measured in the test hole, and decided whether the dry well is feasible.

    Safety : Do not leave a test hole open without covering or fencing it: a child can fall in.

  2. 02Lay out the drain and its fall[4, 5, 10]

    1. Drive a stake at the start and one at the outlet, then intermediate stakes at changes of direction.
    2. Stretch a string that drops at least 1 cm per metre (1%) toward the outlet, checked with a line level or laser.
    3. Mark the trench width on each side of the string with paint.
    4. Check that the route stays outside the 1 m strip around the locate marks, or plan to dig there by hand.

    Done when : The string falls toward the outlet everywhere, at least 1 cm per metre, and the trench width is marked.

  3. 03Dig the trench along the fall[4, 5, 10, 11, 12, 13]

    1. Dig with the mini excavator along the string, to the width and depth the calculator gives.
    2. Check the bottom with a laser or the string every few metres; fix dips by hand.
    3. Near the locate marks, dig by hand.
    4. Place spoil at least 1.2 m from the edge.

    Done when : The trench bottom falls toward the outlet everywhere, with no dip or back-fall, checked with a laser or string every few metres.

    Safety : Never go into a trench deeper than 1.2 m unless its walls are shored or sloped back. Keep soil and materials at least 1.2 m from the edge and machines at least 3 m back. No machine within 1 m of the marks.

Phase 4 · Base

Place the fabric, the stone and the drain

Geotextile lines the trench so fine soil cannot clog the stone. The perforated drain sits on a bed of clear stone, gets covered with stone, then the fabric is closed over the top. Check the fall of the pipe itself, not only the bottom's. The calculator gives the tonnes of stone, the square metres of fabric and the pipe length.

  1. 01Lay the bed, the pipe and the cover[1, 4, 5, 14, 15, 16]

    1. Roll the geotextile into the trench, with overlaps, and leave enough fabric on each side to close it over the top.
    2. Spread a 100 to 150 mm bed of clear stone and set its fall.
    3. Lay the perforated drain (with a sock in silty soil), holes as the manufacturer says, and check its fall every few metres.
    4. Connect the drain to the solid pipe that leads to the outlet.
    5. Cover the pipe with at least 150 mm of clear stone, then close the fabric over the top with an overlap.
    6. Pour water into the high end and check that it comes out at the outlet.

    Done when : Water poured into the high end comes out at the outlet without pooling, the pipe's fall is nowhere flat or reversed, and the fabric is closed over the stone.

    Safety : Stone and rolls are heavy: half-full wheelbarrow, gloves and safety boots.

  2. 02Install a catch basin at the low spot[4, 5, 13, 17]

    This step applies only to a catch basin.

    1. Place the catch basin at the low spot where water collects.
    2. Dig its hole and the trench for the solid pipe to the outlet, with a continuous fall of at least 1%.
    3. Set the basin on a compacted bed, its grate slightly below finished grade (about 10 to 20 mm, our estimate) so water gets in.
    4. Connect the solid pipe on a bed of clear stone or sand and check its fall.
    5. Backfill around it by hand and plan to empty the sump every spring.

    Done when : A bucket of water poured into the grate comes out at the outlet, and the grate sits slightly below the surrounding ground.

    Safety : Do not go into a hole deeper than 1.2 m unless its walls are sloped or shored. The basin is heavy and awkward: lift it with two people and keep spoil at least 1.2 m from the edge.

Phase 5 · Install and finish

Backfill, connect the downspouts and finish the surface

Above the fabric, backfill with site soil and reshape the surface so water heads to the swale or the outlet rather than the house. Downspouts are extended away from the foundation and discharge onto a surface that absorbs, never into the foundation drain. A catch basin goes at the low spot, its grate slightly below the surrounding ground, and connects through a sloped solid pipe. A dry well needs soil that absorbs: do an infiltration test before building it.

  1. 01Backfill and reshape the slopes[2, 4, 18]

    1. Put the site soil back over the fabric, in lifts, lightly compacting each lift.
    2. Keep the surface slightly crowned over the trench: it will settle.
    3. Reshape the slopes: the ground falls away from the foundation, and the lawn keeps at least 2% toward the swale or outlet.
    4. For a swale, keep at least 150 mm of depth and gentle sides (no steeper than 3 to 1).
    5. Put the topsoil and sod back.

    Done when : Water from a hose on the reshaped ground runs to the swale or outlet, away from the house and not toward the neighbour.

    Safety : Bend your knees when shovelling and switch tasks to spare your back. Wear gloves and boots; do not stand on fresh fill at the edge of a trench that is still open.

  2. 02Extend the downspouts[2, 4]

    1. Disconnect any downspout tied into the foundation drain, if your municipality allows or requires it.
    2. Add an extension to discharge water away from the foundation, onto a splash pad.
    3. Send the water toward lawn, a planting bed or a swale, not a driveway, a walk or the neighbour's land.
    4. For a catch basin or a dry well, connect the downspout through a sloped solid pipe.

    Done when : Every downspout discharges away from the foundation onto a surface that absorbs, and none is tied into the foundation drain.

  3. 03Test and maintain the drainage[2, 4, 5]

    1. Run a garden hose into the start of the drain and at each downspout: the water must come out at the outlet without coming back toward the house.
    2. Mark the outlet with a stake so you can find it under snow, and keep it clear of leaves and ice.
    3. After the first heavy rains, walk the yard again: puddles, soil settled over the trench, an outlet that does not flow.
    4. Every spring, empty the catch basin sump and check the downspout extensions.

    Done when : Hose water comes out at the outlet, the outlet is marked and clear, and a spring check is in the calendar.

Common mistakes

Sending the water to the neighbour[3]

What happens

You make the flow onto the lower land worse, which the Civil Code forbids, and risk a dispute and the cost of fixing it.

How to avoid it

Keep outlets on your land, at least 2 m from the line, and do not concentrate water toward the neighbour.

Tying downspouts into the foundation drain[2]

What happens

Roof water floods the foundation drain at the worst moment and can get into the basement.

How to avoid it

Discharge downspouts at the surface, away from the foundation, onto a surface that absorbs.

A French drain with no outlet[5]

What happens

The drain fills up, holds water and does nothing.

How to avoid it

Plan the outlet before digging: daylight, dry well or an allowed system.

A flat or back-sloped drain[5]

What happens

Water sits in the dips, drops silt and clogs the drain within a few years.

How to avoid it

At least 1% of fall, never under 0.5%, checked with a laser or string on the pipe itself.

Leaving out the geotextile in fine soil[14]

What happens

Silt and clay migrate into the stone and clog the drain.

How to avoid it

Wrap the stone in a non-woven geotextile, and use a socked drain in silty soil.

Ground that slopes toward the house[1, 2]

What happens

Surface water collects against the foundation, even with a drain.

How to avoid it

Reshape the slope to shed water: 10% over the first 2 m at backfill according to the APCHQ.

A dry well too close to the house or in soil that does not absorb[6]

What happens

Water comes back toward the foundation or stays in the well, which overflows.

How to avoid it

Do an infiltration test, keep the well away from the foundation (we plan at least 3 m, an estimate) and check municipal stormwater rules.

Going into a deep trench[12]

What happens

A wall that caves in can bury the person at the bottom.

How to avoid it

Beyond 1.2 m, shore or slope the walls before going in; otherwise, work from the edge.

Digging without a locate request[9]

What happens

A long drain trench often crosses a cable or a pipe.

How to avoid it

File the Info-Excavation request at least 4 business days ahead and dig by hand near the marks.

When to call a pro or an engineer

  • LocateApplies to the typical project

    File a free Info-Excavation request at least 4 business days before you dig.[9]

  • Land surveyor

    The outlet is less than 2 m from the line: confirm the line with your certificate of location or a land surveyor, and do not send water toward the neighbour.[2, 3]

  • Plumber

    A connection to the storm system or the building drain is plumbing work: hire a plumber who is a CMMTQ member.[7, 19]

  • Municipality

    A connection to the municipal system generally needs a permit and must follow the municipality's stormwater rules.[6]

  • Contractor

    A downspout tied into the foundation drain overloads it: have it disconnected and discharged at the surface, away from the house.[2]

  • Contractor

    A dry well less than 3 m from the foundation may send water back toward the basement: have the location checked.[6]

  • Contractor

    Without an infiltration test, nobody knows whether the soil will absorb the dry well's water: have the test done before building it.[6, 20]

  • Contractor

    Trench deeper than 1.2 m that someone enters: shoring or sloped walls required. Hire an equipped business.[12]

  • Contractor

    Less than 0.5% of fall: the drain will not flow. Rework the route, depth or outlet with a professional.[5]

  • Municipality

    Near a watercourse, a shoreline or a steep slope, special municipal rules apply: check them before changing the drainage.[6]

  • Contractor

    A slope steeper than 33% does not hold well without a structure: have the stabilization or the wall designed.[2, 6]

Rules in Quebec

  • NeighboursAll of Quebec

    Lower land receives the natural flow of water from higher land, but the upper owner may not make the neighbour's situation worse (Civil Code of Quebec, art. 979). Do not aim your downspouts, drains or slopes at the neighbouring lot.[3, 21]

    Checked October 10, 2026

  • LicenceAll of Quebec

    Yard drains, French drains and swales not connected to a building, as well as foundation drains, are excluded from the Construction Code's plumbing chapter. A connection to the building drain or the municipal sewer belongs to a plumber who is a CMMTQ member (interpretation, to confirm with your municipality).[7, 19]

    Checked October 10, 2026

  • Permitquebec

    Quebec City: increases in impervious area refer to the stormwater management sheets; near water and steep slopes, special rules apply; slopes are limited to 50% and 3 m high.[6]

    Checked October 10, 2026

  • Permitsaint-remi

    Saint-Rémi: the explanatory document on rainwater management asks for a 10% slope over the first 1.8 m around the house, and about 2% toward the street. An example of a local drainage rule.[8]

    Checked October 10, 2026

  • SafetyAll of Quebec

    Never go into a trench deeper than 1.2 m unless its walls are shored or sloped back. Keep soil and materials at least 1.2 m from the edge and machines at least 3 m back. These rules bind employers; the danger is the same for a homeowner.[12]

    Checked October 10, 2026

  • LocateAll of Quebec

    Before digging, file a free Info-Excavation request at least 4 business days ahead; it is valid 180 days at most.[9]

    Checked October 10, 2026

Words used

Sources

  1. 1.

    Fiche technique S3-05 : fondations de béton (détail du nivellement et du drain) · APCHQ

    Consulted October 10, 2026Source page

    • The APCHQ plans a 10% slope over 2 m along the foundation at backfill, which later settles to about 2%.
    • The APCHQ detail covers the foundation drain with 150 mm of 19 mm clear stone.
    • 10% slope over 2 m at backfill.
    • Slope along the foundation and drain cover.
  2. 2.

    Guide to Lot Drainage · City of Calgary

    Consulted October 10, 2026Source page

    • The Calgary guide asks for at least 4% over 1.2 m next to the foundation and at least 2% for lawns and swales.
    • The Calgary guide keeps downspout outlets at least 2 m from public infrastructure.
    • Calgary recommends consulting a professional before building a dry well, because topography and soil decide how well it works. (section 5.3)
    • At least 2% of fall for lawns and swales.
  3. 3.

    Écoulement des eaux (rapports de voisinage) · Gouvernement du Québec

    Consulted October 10, 2026Source page

    • Lower land receives natural runoff; the upper owner may not make it worse. (C.c.Q. art. 979)
    • Summary of article 979. (C.c.Q. art. 979)
    • Ban on making runoff onto the neighbour worse. (C.c.Q. art. 979)
    • Quebec government summary. (C.c.Q. art. 979)
  4. 4.

    Experience curve effects · Wikipedia

    Consulted October 10, 2026Source page

    • Wright's law links task time to the number of repetitions; published progress ratios range from 0.75 to 0.90.
  5. 5.

    Pente minimale d'un drain français au Québec · Soumission Rénovation

    Consulted October 10, 2026Source page

    • The minimum fall cited in Quebec for a French drain is 1%, with an absolute minimum of about 0.5%.
    • Minimum fall of 1%, absolute minimum about 0.5%.
    • The pipe must keep at least 1% of fall to the outlet.
    • The pipe keeps at least 1% of fall to the outlet.
  6. 6.

    Fiche 60 : Mur de soutènement, clôture et talus combinés (juillet 2023) · Ville de Québec

    Consulted October 10, 2026Source page

    • Quebec City refers increases in impervious area to its stormwater management information sheets.
    • Quebec City refers increases in impervious area to its stormwater rules.
    • Quebec City frames stormwater management through its information sheets.
    • Municipal stormwater rules to check.
  7. 7.

    Code de construction, RLRQ c. B-1.1, r. 2 · LégisQuébec, Éditeur officiel du Québec

    Consulted October 10, 2026Source page

    • Chapter III of the Construction Code excludes piping not attached to a building and foundation drains from plumbing. (art. 3.02.01)
    • Plumbing covers installations connected to the building; unconnected yard drains are excluded. (art. 3.02.01)
    • Chapter III exclusions. (art. 3.02.01)
    • Yard drains excluded from plumbing. (art. 3.02.01)
  8. 8.

    Document explicatif : gestion des eaux pluviales · Ville de Saint-Rémi

    Consulted October 10, 2026Source page

    • Saint-Rémi publishes an explanatory document on rainwater management that asks for a 10% slope over the first 1.8 m around the house.
    • Saint-Rémi explanatory document.
  9. 9.

    Travaux d'excavation · Régie du bâtiment du Québec

    Consulted October 10, 2026Source page

    • Info-Excavation request at least 4 business days before the work, free, valid 180 days at most.
    • 4 business day lead time.
    • RBQ page on excavation work.
  10. 10.

    Fiche technique 34, Protéger les services publics souterrains · APSAM (Association paritaire pour la santé et la sécurité du travail, secteur affaires municipales)

    Consulted October 10, 2026Source page

    • 1 m strip exposed by hand on each side of the marks.
  11. 11.

    Mini-excavatrice en location : est-ce rentable pour creuser votre drain vous-même ? · Construction Rénovation Québec

    Published March 21, 2024Consulted October 10, 2026Source page

    • Construction Rénovation Québec covers renting a 1.5 t mini excavator to dig your own drain, with round-trip delivery or towing it yourself.
  12. 12.

    Code de sécurité pour les travaux de construction, RLRQ c. S-2.1, r. 4 · Gouvernement du Québec (LégisQuébec)

    Consulted October 10, 2026Source page

    • 1.2 m rules for walls and materials, and 3 m for machines. (art. 3.15.3)
    • Shoring rules. (art. 3.15.3)
    • Construction safety code. (art. 3.15.3)
  13. 13.

    Guide des prix d'excavation : tout ce qu'il faut savoir · Soumission Rénovation

    Published May 7, 2026Consulted October 10, 2026Source page

    • Soumission Rénovation gives 4 to 6 mini excavator hours for 100 linear feet of trench 2 to 3 feet deep.
  14. 14.

    DTNI-3C, Mise en oeuvre des pavés et des dalles en béton ou en pierre naturelle sur lit de pose granulaire · Ville de Montréal

    Published October 3, 2024Consulted October 10, 2026Source page

    • For filtering use, Montreal specifies a non-woven geotextile meeting BNQ 7009-210. (s. 6.5.2)
    • Non-woven geotextile for filtering use. (s. 6.5.2)
  15. 15.

    TS 3.80, Construction Specification for Concrete Unit Pavers · City of Toronto

    Consulted October 10, 2026Source page

    • Toronto publishes the gradation of a 19 mm clear stone with almost no fines. (Table 4)
  16. 16.

    Coût d'un drain français au pied linéaire au Québec en 2026 : guide complet · Soumission Rénovation

    Published September 18, 2026Consulted October 10, 2026Source page

    • Soumission Rénovation publishes 100 to 150 $ per linear foot for a foundation French drain; a shallower yard drain should cost clearly less.
  17. 17.

    puisard (fiche du Grand dictionnaire terminologique) · Office québécois de la langue française

    Consulted October 10, 2026Source page

    • The OQLF describes a catch basin as a shallow well with a grate and a settling basin that carries runoff away.
  18. 18.

    Lot Grading Plan Review Checklist · Town of Midland (Ontario)

    Consulted October 10, 2026Source page

    • Swale at least 150 mm deep, sides no steeper than 3 to 1.
  19. 19.

    Liste des sous-catégories de licence (document 1592, édition 2025-10) · Régie du bâtiment du Québec

    Consulted October 10, 2026Source page

    • Subcategory 15.5, plumbing.
  20. 20.

    puisard d'absorption, puits perdu (fiche du Grand dictionnaire terminologique) · Office québécois de la langue française

    Consulted October 10, 2026Source page

    • A dry well disposes of water by percolation into the soil: it works only if the soil lets water through.
  21. 21.

    Code civil du Québec, RLRQ c. CCQ-1991 · LégisQuébec, Éditeur officiel du Québec

    Consulted October 10, 2026Source page

    • Civil Code text. (art. 979)

Review and history

Status
Draft awaiting review
Last reviewed
October 10, 2026
Next review due
April 10, 2027
Reviewers
Rédaction paysagement (editor)
Change log
  1. October 10, 2026

    First version, written from the article 979 summary, the Calgary and APCHQ drainage guidance and the trench safety rules. Draft awaiting review by an installer.