Can You Use Treated Wastewater to Irrigate Your Garden?

For homeowners living on rural, semi-rural or unsewered properties, an onsite wastewater treatment system does more than simply collect wastewater from the house.

After wastewater has been treated, it still needs to go somewhere.

In many onsite wastewater systems, appropriately treated effluent is directed to an approved land application or irrigation area on the property.

This leads to a common question from homeowners:

Can treated wastewater actually be used to irrigate your garden?

The answer is that treated wastewater can form part of an approved irrigation system, but it should never be treated in the same way as ordinary drinking water or unrestricted garden water.

Where it can be applied, what can be planted in the irrigation area and how the area can be used will depend on the wastewater treatment system, the quality of the treated effluent, whether surface or subsurface irrigation is being used, the property’s wastewater report, site conditions and local council requirements.

Understanding these limitations is important because wastewater irrigation is first and foremost a method of safely managing treated household wastewater.

The benefit to vegetation is secondary.

This guide explains where treated wastewater may generally be used, what types of vegetation may be appropriate, which areas should be avoided, the health considerations homeowners need to understand and why the approved wastewater design should always determine how the irrigation area is managed.

What Is Treated Wastewater?

Treated wastewater is household wastewater that has passed through an onsite wastewater treatment system before being discharged to an approved land application area.

Household wastewater can originate from:

• Toilets.
• Showers.
• Baths.
• Bathroom basins.
• Kitchen sinks.
• Dishwashers.
• Washing machines.
• Laundries.
• Other household plumbing fixtures.

Depending on the treatment system, wastewater may pass through a number of treatment stages designed to reduce solids, organic material and other contaminants before the treated effluent leaves the system.

An aerated wastewater treatment system, commonly called an AWTS, uses treatment processes beyond basic settlement to improve the quality of the final effluent.

However, the important point for homeowners is that treated wastewater is not drinking water.

It remains wastewater and should be used and managed only in accordance with the approved onsite wastewater design.

Why Is Treated Wastewater Irrigated?

When a home is connected to a sewer network, wastewater leaves the property and is treated through larger sewerage infrastructure.

An onsite system works differently.

Wastewater generated by the household is managed on the property.

Once it has been appropriately treated, the resulting effluent is commonly directed to a designated land application area.

This allows the property to manage its wastewater in a controlled way.

Vegetation and soil can play a role in this process by helping manage water and nutrients.

The purpose of the irrigation area is therefore not simply to keep the garden green.

It is part of the wastewater management system.

That distinction is extremely important when planning landscaping.

Can Treated Wastewater Be Used on Lawn?

Lawn and appropriately selected grassed areas can often form part of an approved wastewater irrigation area.

Grass can be useful because it provides vegetation across a relatively large area and can help utilise water and nutrients.

A grassed irrigation area may also remain accessible for inspection and maintenance.

However, homeowners need to remember that the lawn is still an approved wastewater land application area.

It should be maintained in a way that does not damage irrigation equipment or interfere with the system.

For surface irrigation, sprinkler heads should be protected when mowing.

For subsurface irrigation, homeowners need to know where underground irrigation lines are located so they are not damaged during landscaping or excavation.

Can You Use Treated Wastewater on Ornamental Gardens?

Depending on the approved wastewater system and site design, ornamental vegetation may be incorporated into wastewater irrigation areas.

Plants that use water effectively and have root systems that will not damage underground irrigation infrastructure may be suitable in some situations.

The exact vegetation should be chosen with the irrigation system in mind.

Before establishing large landscaped gardens over an irrigation area, ask your wastewater consultant, installer or service provider whether the proposed plants are appropriate.

The fact that a plant enjoys moist soil does not automatically make it suitable.

Its root behaviour, mature size and the amount of excavation required to plant it also matter.

What Plants May Be Suitable?

There is no universal plant list that will suit every wastewater irrigation area.

The best vegetation will depend on climate, soil, irrigation method, site design and local conditions.

Generally, homeowners should consider vegetation that:

• Provides good ground coverage.
• Uses moisture effectively.
• Is suited to the local climate.
• Can tolerate the site’s soil conditions.
• Does not require deep excavation around irrigation pipes.
• Does not have highly aggressive root systems.
• Can be maintained without damaging irrigation infrastructure.
• Grasses and suitable ornamental species may work well in appropriately designed areas.
• Local native species may also be suitable depending on the individual site.

If you are planning significant landscaping, obtaining advice before planting is much easier than removing mature plants later.

Be Careful With Large Trees

Large trees require particular consideration around wastewater irrigation systems.

Tree roots naturally seek moisture.

A wastewater irrigation area can therefore be attractive to root systems.

Aggressive roots may interfere with subsurface irrigation lines or other wastewater infrastructure.

Trees can also create access problems when wastewater components need to be inspected or repaired.

This does not mean that every tree must be removed from every property containing an onsite wastewater system.

It means the position and species of trees should form part of the wastewater and landscaping plan.

Avoid planting large trees directly over subsurface irrigation lines without professional advice.

Can Treated Wastewater Be Used on a Vegetable Garden?

This is an area where homeowners should be particularly cautious.

Do not assume that because treated wastewater can irrigate landscaping, it is automatically suitable for direct application to vegetables, herbs, fruit or other food crops.

The permitted use depends on the treatment standard, irrigation method, approved wastewater design and applicable health and council requirements.

Food plants create additional potential pathways for human exposure.

For that reason, homeowners should follow the exact conditions applying to their wastewater system rather than improvising.

If your intention is to grow edible produce near an irrigation area, discuss the proposed layout with your wastewater consultant and council during the design stage.

A separate garden area supplied by an appropriate water source may be the simpler solution.

Treated Wastewater Is Not Drinking Water

This is the most important health message in this article.

Even when household wastewater has been treated through a wastewater treatment system, homeowners should not regard it as potable water.

• It should not be used for drinking.
• It should not be used for food preparation.
• People should not intentionally drink from wastewater irrigation sprinklers.
• Children should not play in wastewater irrigation water.
• Pets should not be encouraged to drink from irrigation outlets.
• Wastewater irrigation components should not be confused with ordinary garden water systems.

Keeping these distinctions clear is an important part of safely managing an onsite wastewater property.

Surface Irrigation Requires Additional Awareness

Surface irrigation distributes treated wastewater above the ground.

Where approved, sprinklers or other distribution devices spread the treated wastewater across the designated land application area.

Because the water is being distributed above ground, homeowners can generally see when the system is operating.

This makes some maintenance problems easier to identify.

However, it also means people and animals may potentially come into contact with the irrigation area.

• The area therefore needs to be managed appropriately.
• Sprinklers should remain within their approved positions.
• They should not be redirected toward:
• Outdoor entertaining areas.
• Neighbouring properties.
• Roadways.
• Buildings.
• Children’s play equipment.
• Swimming pools.
• Other areas outside the approved irrigation zone.

If a sprinkler is damaged, replacing or relocating it should be done in accordance with the wastewater system requirements.

Subsurface Irrigation Keeps Distribution Below Ground

Subsurface irrigation delivers treated wastewater below the soil surface through buried irrigation lines.

For many homeowners, this is aesthetically attractive because there may be no visible sprinkler heads.

The lawn or landscaping can look relatively normal.

However, the irrigation area remains part of the wastewater system.

Subsurface irrigation does not mean homeowners can forget where the system is located.

Underground lines can potentially be damaged by:

• Excavation.
• Fence construction.
• Tree planting.
• Retaining walls.
• Heavy vehicles.
• New sheds.
• Swimming pools.
• Landscaping equipment.
• Future building work.

Keep a copy of the irrigation layout with your property records.

Can Children Play in a Wastewater Irrigation Area?

Homeowners should manage access according to the design and conditions applying to their wastewater system.

Surface wastewater irrigation areas in particular should not be treated like ordinary sprinkler play areas.

Children should not deliberately play in treated wastewater spray.

If your family needs a dedicated children’s play area, this should be considered when planning the wastewater irrigation layout.

Ideally, the wastewater area, playground, pool and primary recreation spaces should be planned together during the design of the property.

This is much easier than discovering after installation that your preferred play area overlaps with the approved land application zone.

What About Pets?

Pets can also interfere with wastewater irrigation systems.

Dogs may chew, dig around or damage exposed components.

Larger animals may damage sprinkler heads or compact areas of soil.

Pets should not be encouraged to drink treated wastewater.

If animals are likely to occupy the irrigation area regularly, discuss this with the wastewater designer.

Rural properties containing horses, livestock and working dogs may require particularly careful planning.

Can Livestock Graze on Wastewater Irrigation Areas?

Do not assume that a wastewater irrigation area can automatically double as livestock grazing land.

Human health, animal exposure and food-chain considerations may apply.

The approved design and relevant requirements need to determine whether a proposed use is suitable.

If your property is used for agricultural purposes, make that clear when your wastewater report is being prepared.

The wastewater consultant needs to understand how the surrounding land is actually used.

Keep Irrigation Away From Swimming Pools

Swimming pools and wastewater irrigation areas need careful planning.

Homeowners should not allow surface wastewater irrigation to spray into a swimming pool or onto surrounding recreation areas.

Pool construction can also dramatically reduce the land available for wastewater irrigation.

A pool includes more than the water itself.

Consider the:

• Pool shell.
• Surrounding paving.
• Fencing.
• Pool equipment.
• Access paths.
• Landscaping.
• Entertaining area.

All of these can affect the wastewater layout.

If you plan to install a pool in the future, include it on your site plans before finalising the wastewater irrigation area.

Keep Wastewater Away From Outdoor Entertaining Areas

Patios, decks, barbecue areas and outdoor dining spaces are generally high-use parts of a property.

They should be considered carefully when locating wastewater irrigation.

The aim is to create sensible separation between wastewater management areas and places where people regularly eat, relax and entertain.

This is another reason early property planning is valuable.

A wastewater system should work with the home layout rather than becoming an obstacle later.

Waterways, Dams and Drainage Areas Need Protection

Treated wastewater should remain within the approved land application area.

It should not be allowed to run uncontrolled into waterways, drainage channels, neighbouring properties or other sensitive areas.

Wastewater irrigation designs take site conditions and environmental risks into account.

The NSW EPA’s guidance on effluent irrigation emphasises that irrigation should be managed in an environmentally responsible way rather than simply used as a disposal method.

Homeowners can help by watching for water leaving the designated area, particularly following heavy rain.

What Happens During Heavy Rain?

Heavy rainfall can make wastewater irrigation more challenging because the soil is already receiving water from the weather.

At the same time, wastewater continues to be generated inside the home.

This is one reason good household water management can be particularly useful during extended wet periods.

Homeowners can reduce unnecessary wastewater loads by:

• Taking shorter showers.
• Spreading washing loads across the week.
• Repairing leaking toilets.
• Repairing dripping taps.
• Avoiding unnecessary high water use.
• Keeping stormwater out of the wastewater treatment system.

Stormwater should not be deliberately directed into the wastewater treatment tank or irrigation system.

Do Not Connect Wastewater Irrigation to Ordinary Garden Taps

Wastewater irrigation infrastructure should remain clearly separate from potable or ordinary household water systems.

Homeowners and future occupants need to understand which infrastructure carries treated wastewater.

Never create cross connections between wastewater equipment and drinking water plumbing.

If changes to the irrigation system are required, use appropriately qualified people and follow the approved design.

Why Irrigation Area Size Matters

A wastewater irrigation area needs enough suitable land to manage the volume of treated wastewater produced by the household.

Making the area smaller simply because a homeowner wants more lawn for another purpose can create problems.

Applying too much wastewater to too small an area may contribute to:

• Persistent wet patches.
• Ponding.
• Poor soil conditions.
• Odours.
• Uneven vegetation.
• Wastewater leaving the intended area.
• System alarms or operational problems.

The required irrigation area is determined through wastewater design and should be respected.

Good Vegetation Can Help the System

A healthy irrigation area provides more than visual appeal.

Vegetation can help use water and nutrients.

Maintaining good plant coverage can therefore form part of responsible land application management.

Bare, compacted or damaged areas may not perform as effectively as appropriately vegetated land.

However, adding fertilisers or other products to an irrigation area without understanding the existing nutrient load is not necessarily beneficial.

The land is already receiving treated wastewater.

If you are planning significant garden improvements, seek advice appropriate to the site.

Household Cleaning Products Can Affect Wastewater Systems

What you put down household drains can influence the biological processes occurring inside a wastewater treatment system.

Homeowners should follow the manufacturer’s recommendations regarding cleaning products and chemicals.

Avoid treating the wastewater system like a disposal point for:

• Paint.
• Solvents.
• Pesticides.
• Motor oil.
• Large quantities of disinfectant.
• Unwanted medicines.
• Other inappropriate chemicals.

A wastewater treatment system relies on controlled treatment processes.

Protecting the treatment system helps protect the quality of effluent being sent to the irrigation area.

Watch for Warning Signs in the Garden

Vegetation can sometimes provide useful clues about wastewater system performance.

Potential warning signs include:

• One unusually lush patch of lawn.
• Persistent wet areas.
• Grass dying in particular locations.
• Water surfacing above buried lines.
• Strong wastewater odours.
• Soil remaining saturated.
• Visible wastewater runoff.
• Sprinklers operating unevenly.
• Repeated pump alarms.

These signs do not necessarily identify the exact fault, but they indicate that the system deserves investigation.

What If the Garden Smells Like Wastewater?

A properly functioning wastewater irrigation area should not simply be accepted as an ongoing source of strong sewage odours.

Persistent odours can indicate a treatment, distribution or land application problem.

Possible causes may include:

• Treatment performance problems.
• Damaged irrigation pipework.
• Excessive wastewater loading.
• Pump problems.
• Poor distribution.
• Saturated ground.
• Maintenance issues.

Contact your wastewater service provider rather than masking the smell or moving irrigation equipment yourself.

Regular Servicing Is Essential

Wastewater treatment systems contain components that need ongoing servicing.

Depending on the system these can include:

• Pumps.
• Blowers.
• Control equipment.
• Alarms.
• Treatment chambers.
• Filters.
• Disinfection components.
• Irrigation equipment.

Servicing helps identify issues before they become major failures.

If the treatment system is not operating correctly, the quality of wastewater being sent to the irrigation area may also be affected.

That is why the garden irrigation system and treatment plant should be thought of as one complete wastewater management arrangement.

What Does Council Approval Have to Do With Your Garden?

For NSW properties, local councils regulate onsite sewage management arrangements.

The wastewater treatment system and land application area can be part of the approval process.

That means homeowners should not substantially relocate or redesign wastewater irrigation solely to suit new landscaping without first determining whether approval is required.

The irrigation area shown on wastewater plans was selected for a reason.

Before constructing a pool, shed, retaining wall, extension or large garden over that area, check the implications.

What If You Buy a House With Existing Wastewater Irrigation?

If you are buying a rural property, ask where the wastewater irrigation area is located.

Request available:

• Wastewater reports.
• Council approvals.
• Irrigation plans.
• System information.
• Service records.
• Approval to operate information where applicable.
• Pump replacement records.
• Maintenance history.

Walk around the irrigation area during the property inspection.

Look for wet patches, odours, damaged sprinklers or unusual vegetation.

Knowing what you are buying is far better than discovering an undocumented irrigation system after settlement.

Can You Move the Irrigation Area Later?

Potentially, but it should not be regarded as a simple DIY landscaping change.

Relocating an irrigation area may require:

• Assessment of the new area.
• Soil considerations.
• New irrigation design.
• Pipework changes.
• Pump considerations.
• Updated plans.
• Council involvement or approval.
• Professional installation.

If you have future plans for a pool, shed or extension, identify them before the original wastewater system is installed.

Design the Garden and Wastewater System Together

One of the best ways to create an attractive property with onsite wastewater is to plan landscaping and wastewater management together.

Before installation, identify:

• House location.
• Driveway.
• Garage.
• Pool.
• Outdoor entertaining area.
• Children’s play areas.
• Major gardens.
• Existing trees.
• Future sheds.
• Vehicle access.
• Wastewater treatment tank.
• Irrigation area.

When these features are considered together, the wastewater irrigation area can become an integrated part of the overall property design rather than an afterthought.

Can Treated Wastewater Be Beneficial to Landscaping?

Appropriately managed treated wastewater can provide water to vegetation and contribute to reducing the need for another irrigation source within the designated area.

However, homeowners should avoid thinking of wastewater as “free garden water” that can simply be redirected wherever plants look dry.

• The wastewater must be managed regardless of whether the garden needs watering that day.
• That is a fundamental difference between wastewater irrigation and an ordinary garden irrigation system.
• An ordinary sprinkler system can simply be turned off when the lawn has enough water.
• The household continues producing wastewater.
• The onsite wastewater system therefore needs to be designed around year-round wastewater management.
• The Best Garden Is One That Works With Your Wastewater System
• Treated wastewater and attractive landscaping can coexist successfully when the property is properly planned.
• The key is understanding that the wastewater irrigation area has a job to perform.
• Select suitable vegetation.
• Protect the irrigation infrastructure.
• Keep recreational and sensitive areas separate where required.
• Do not plant aggressive trees directly over subsurface lines.
• Do not move sprinklers because one part of the garden needs more water.
• Do not treat wastewater as potable water.
• Maintain the treatment system.
• Follow council and wastewater design requirements.

When these principles are followed, the irrigation area can become a functional and well-maintained part of the property.

Talk to Eco Septic About Your Wastewater System

If you are planning a new onsite wastewater system, replacing an existing system or building on an unsewered property, understanding how the treated wastewater will be managed is just as important as choosing the treatment tank.

At Eco Septic, we recommend having your wastewater report available when requesting a quote wherever possible.

The report can help identify the required treatment standard, expected wastewater load, approved irrigation method and land application requirements.

From there, the wastewater treatment system and associated irrigation equipment can be considered as part of the complete solution.

If you are still at the early planning stage, speak with your wastewater consultant and local council about what is required for your property.

The Final Answer

So, can you use treated wastewater to irrigate your garden?

Treated wastewater can be applied to suitable vegetation within an appropriately designed and approved wastewater irrigation area, but it is not ordinary garden water and it should not be used without restrictions.

The exact plants, irrigation method and permitted uses will depend on your wastewater system and property.

Keep food production, recreation and sensitive areas in mind.

Protect children and pets from unnecessary exposure.

Keep wastewater infrastructure separate from drinking water systems.

Maintain your system.

And most importantly, follow the wastewater design and local council requirements applying to your property.

With appropriate planning, your wastewater irrigation area can support healthy vegetation while performing its most important role: safely managing the treated wastewater produced by your home.