Greywater for landscaping reuses water from showers, baths, bathroom sinks and laundry to irrigate shrubs and trees through mulch basins or subsurface lines. In Ontario the Building Code treats greywater as sewage, so a system that discharges to the ground needs a design and a permit, and outdoor systems must divert back to the drain in winter. Plan and permit over the winter for a spring install.
Key takeaways
Greywater for landscaping means reusing lightly used water from showers, bathtubs, bathroom sinks and washing machines to irrigate plants instead of sending it down the drain. It can cut the amount of treated water you use on the garden, but it has to be done with the right soaps, the right plants and subsurface or mulch-basin distribution so people and pets never contact it. In Ontario there is one more step: the Building Code treats greywater as sewage, so any system that sends it into the ground needs a design and a permit. This guide covers how greywater systems work, what is allowed here, which plants suit our climate and how to plan a system for 2027.
Most guides to greywater are written for dry, warm US states. Simcoe County has freezing winters, many homes on private wells and septic systems, and different rules, so the advice below is adjusted for Midland, Penetanguishene and the surrounding townships.
What is Greywater?
Greywater is wastewater from non-toilet plumbing systems. It includes water from:
- Showers and bathtubs
- Bathroom sinks
- Laundry machines (especially rinse cycles)
It does not include blackwater from toilets. Most greywater guidance also leaves out kitchen sinks and dishwashers, because grease, food particles and higher bacteria levels make that water harder to manage. Greywater can be reused in the yard with the right setup, approvals and filtration.
Why Use Greywater in Landscaping?
1. Saves Water
Reusing household water for irrigation reduces the need for fresh water during summer dry spells and lawn-watering restrictions, when outdoor use peaks.
2. Reduces Utility Bills
Showers, baths and laundry produce a large share of a household's indoor wastewater, so a family can generate hundreds of litres of greywater a day. On municipal water, every litre reused outdoors is a litre you do not buy. On a private well, the saving is in pumping and well demand rather than a water bill.
3. Supports Sustainable Landscaping
Greywater use promotes xeriscaping, native planting, and other water-conscious practices that align with long-term environmental health.
4. Enhances Soil Moisture and Retention
Used correctly, greywater helps maintain optimal moisture levels in soil, making your plants more resilient during hot, dry spells.
Types of Greywater Systems for Landscaping
| System Type | Best For | Key Features | Estimated Cost | Maintenance Needs | Ideal Plants |
|---|---|---|---|---|---|
| Laundry-to-Landscape | DIY homeowners, small yards | Directs laundry water to mulch basins without storage tanks | $150–$300 (DIY setup) | Low – occasional cleaning filter | Shrubs, ornamental grasses, fruit trees |
| Branch Drain (Gravity) | Households with sloped yards | Uses gravity to distribute greywater from multiple sources through PVC piping | $1,000–$2,500 | Medium – pipe inspection annually | Trees, large garden beds, perennials |
| Pumped System | Flat terrain, large or complex yards | Includes surge tank, pump, and filtration; supports multi-zone irrigation | $3,000–$7,500 | High – pump and filter checks | Native landscaping, mixed-use plant zones |
Laundry-to-Landscape (L2L) Systems
- No storage tanks required
- Sends laundry rinse water directly into the yard
- Low-cost and easy to retrofit
Gravity-Fed Branch Drain Systems
- Distributes water underground via sloped piping
- Ideal for households with high-volume showers
Pumped Systems with Filtration
- Includes surge tanks and filters
- Best for multi-zone irrigation and homes with flat yards
Packaged greywater kits are sold by specialist suppliers such as WaterWise Group, a US company. Check that any product you buy can be approved under Ontario rules before you order it.
Best Practices for Using Greywater in Landscaping
Use Biodegradable Soaps and Detergents
Greywater may contain residues from soaps, so always choose non-toxic, plant-friendly products.
Avoid Greywater Contact with Edible Parts of Plants
Use greywater only on non-edible landscaping plants or on trees and shrubs where the water stays below the mulch and never touches fruit or leaves. Never spray greywater through sprinklers.
Mulch is a Must
Mulch basins around greywater outlets help retain moisture, prevent odour, and reduce runoff.
Rotate Application Zones
Spread greywater across different areas to avoid oversaturation or salt build-up.
Comply with Ontario Rules
In Ontario, greywater is sewage under the Building Code. A system that discharges greywater into the ground on its own is a Class 2 sewage system under Part 8 of the Code and needs a permit from the local sewage system authority before it is built. The Code also allows properly treated greywater to be reused inside a building, for example to flush toilets, under its non-potable water rules. Running a washing machine hose straight onto the garden is not an approved setup here. Talk to your municipality's building department, or the agency that issues septic permits in your township, before you design anything.
Greywater on a septic system
Many homes around Midland, Tiny and Tay run on private septic systems. Diverting greywater away from the septic tank changes how the system was designed and approved, so it needs the same permit review. If you are planning a septic replacement or a new build anyway, that is the right time to ask whether a separate greywater system makes sense.
Plants That Thrive with Greywater
Greywater works best on established, deep-rooted shrubs and trees that tolerate slightly alkaline water and occasional salt from detergents. For Simcoe County gardens (roughly Canada hardiness zone 5), good choices include:
- Native shrubs such as red osier dogwood, ninebark, elderberry and serviceberry
- Willows, kept well away from pipes, foundations and septic beds
- Ornamental and native grasses such as switchgrass
- Fruit trees, watered below the mulch and never on the fruit
- Mature shade trees such as maples, with water spread around the drip line
Avoid acid-loving plants such as rhododendrons and blueberries, which do poorly with the slightly alkaline water most detergents leave behind. Our planting team can match species to your soil and exposure.
Water Retention and Soil Health
One of the hidden benefits of greywater is its impact on soil structure and retention. Greywater can:
- Improve soil microbial activity, breaking down organic matter
- Increase soil porosity, allowing water to infiltrate more efficiently
- Help develop deeper root systems for plants, reducing overall watering needs
Mulched greywater basins and subsurface lines also lose far less water to evaporation than overhead sprinklers, because the water goes straight into the soil.
How to Build a Simple Greywater Basin
Once your design is approved, a mulch basin outlet is the simplest way to distribute greywater. The basic layout looks like this:
- Choose a spot at least 3 m from your home's foundation and well clear of your well, septic bed and property lines
- Dig a shallow basin about 300–450 mm deep
- Layer with gravel and mulch
- Direct laundry greywater through PVC pipe
- Test flow and cover with additional mulch
Tip: Install a diverter valve so greywater can go back to the sewer or septic system during wet weather and all winter, to prevent pooling and frozen lines.
Field drawing 01 · Measuring
Measure area, slope and volume before you order
Three numbers drive every landscape quote: square metres, fall and cubic metres.
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- Split odd shapes. Break the yard into rectangles, triangles and circle segments, measure each, then add them.
- Level a string line. Stretch it between two stakes and set a line level in the middle so the string is dead level.
- Measure down at each stake. The difference is the rise. Divide by the run between stakes and multiply by 100 for percent.
- Volume = area × depth. Convert depth to metres first. Tell the supplier the compacted depth you need.
- Check against the standard. In Midland, grass must fall at least 2% away from buildings and hard surfaces at least 1%.
Gravity branch drains only work if the pipe falls steadily from the house to each outlet, so measure the slope across the yard before you plan the route. Size each mulch basin from its area and depth to know how much mulch to order. Check the drainage around the house at the same time: in Midland, lawn areas must fall at least 2% away from buildings, and a greywater outlet should never send water back toward the foundation. If the grade needs work first, our lot grading crew can set it up before the system goes in.
Greywater and Climate Resilience
Using greywater isn't just about your backyard—it's part of a larger strategy to create climate-resilient communities. By reducing strain on municipal systems, homeowners contribute to:
- Lowered urban heat island effect (due to healthier, shaded green spaces)
- Decreased stormwater runoff
- Increased biodiversity in suburban areas
Common Mistakes to Avoid
- Using greywater from kitchen sinks (grease and food particles = harmful to plants)
- Overusing water in one area, leading to root rot
- Ignoring seasonal adjustments, such as diverting to the sewer or septic system before the first hard frost
- Skipping system maintenance (filters and valves clog)
Cost and ROI
Typical 2026 cost ranges, drawn from US installations, are below. Ontario projects also carry design and permit costs, and in some cases septic review, so get local quotes before you budget.
- DIY Laundry-to-Landscape: $150–$300
- Professional Branch Drain System: $1,000–$2,500
- High-end Pumped Systems: $3,000–$7,500
Annual savings depend on your water and wastewater rates and how much you irrigate. In Simcoe County the irrigation season runs only from about May to September, so payback is slower than in year-round climates.
Planning a 2027 greywater landscaping system
If you want greywater watering your garden next summer, start the paperwork this winter. Outdoor greywater systems in Ontario need a design and a permit before installation, and approvals take time. Excavation for basins and branch lines can only start once the ground has thawed and dried, which around Midland usually means late April or May. A design settled by February leaves room for the permit review and a spring install, so the system is ready for the July and August dry spells when it saves the most water.
Over the winter, decide which sources to use (laundry alone is the simplest), where the outlets will go, and how the water will get there. Gravity systems need a steady fall from the house to each basin, so a sloped lot may avoid a pump entirely. If your home is on a septic system, ask how diverting greywater affects your existing permit.
- Map the yard. Note the well, septic tank and bed, foundation, property lines and the trees and shrubs you want to water.
- Choose the planting first. Greywater suits established shrubs and trees, not vegetable beds or lawn.
- Line up approvals. Contact your municipal building department before you buy equipment.
- Plan the winter diverter. Every outdoor system here needs a simple way to send water back to the drain from late fall to spring.
FAQs About Greywater for Landscaping
1. Is greywater safe for my garden?
Yes, if it comes from safe sources (laundry, baths, bathroom sinks) and doesn't contain harmful chemicals or grease.
2. Can greywater be stored for later use?
Not untreated. Untreated greywater should be used within 24 hours to avoid bacteria growth and foul odour. Storage for later reuse calls for a treatment system.
3. Is greywater legal in Ontario?
Yes, with approval. The Ontario Building Code treats greywater as sewage, so a system that discharges it to the ground needs a sewage system permit, and indoor reuse must meet the Code's non-potable water rules. Check with your municipal building department before installation.
4. Can greywater be used in winter?
Not for outdoor irrigation in Simcoe County. Plants are dormant and lines can freeze, so outdoor systems should divert back to the sewer or septic system from late fall until spring.
5. Will using greywater attract pests?
Not if properly filtered, mulched, and underground. Visible pooling or odours indicate poor design.
6. Can greywater harm my soil or plants?
Not if you avoid harmful soaps and rotate usage areas to prevent buildup of salts or residues.
Is greywater right for your landscape?
Greywater for landscaping makes the most sense for homes with established shrubs and trees, a household that produces steady laundry and shower water, and an owner willing to get the design approved and keep the system maintained. It saves the most water in the hottest part of summer, when gardens need it most.
A laundry-to-landscape setup is the smallest starting point. A branch drain or pumped system suits larger yards and more sources. In Ontario, any of them starts with a conversation with your building department.
Product information for kits and pumped systems is available from suppliers such as WaterWise Group. For grading, planting and septic work around a greywater system, contact Forty Five Scapes.
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Frequently asked questions
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