AWTS Irrigation Area Rules in NSW: Sprinklers, Drip Lines, Signs and Setbacks

In NSW, treated effluent from an AWTS can only go onto the irrigation area your council approved, by the method it approved: subsurface drip, surface drip covered with mulch, or low surface sprinklers where council has specifically allowed them. The area has to be signposted, kept free of vegetables, fruit, buildings, cars and stock, and set back from boundaries, buildings, pools and water.

Those rules come from two places. The NSW Office of Local Government’s Onsite Wastewater Management Guidelines (April 2025) set out how councils should assess and condition irrigation areas, and the conditions printed on your own Section 68 approval turn that guidance into obligations for your property. Where the two differ, your approval wins, so dig it out before you change anything in the yard.

What the irrigation area actually is

The guidelines call it the effluent application area, or EAA. On a conventional septic system that’s the absorption trench. On an AWTS it’s usually a lawn or garden zone fed by a pump in the last chamber of the tank, which pushes disinfected effluent out through drip lines or sprinklers.

Council treats it as part of the system, not part of the garden, so a problem on the lawn is a compliance problem in the same way a dead blower is. Septic tank vs AWTS explains the treatment side, and council OSSM inspection rules covers approvals and renewals for each Hunter council.

The three ways AWTS effluent can be irrigated

NSW Health accredits each AWTS design, and its accreditation guideline lists the forms of irrigation the effluent is suitable for: above-ground spray, surface drip covered by mulch, shallow subsurface drip at 100 to 150 mm below ground, and subsurface disposal in trenches or beds. It adds that each form is subject to the approval of the local council, and that the effluent is not for internal household reuse. So an accredited unit can legally feed sprinklers, but only if your council has approved sprinklers for your site.

Two things are off the table whichever method you have. The guidelines say open pipe irrigation and domestic hoses are not allowed, and that flood irrigation, soaker hoses and end-of-pipe discharge are not permitted surface irrigation options.

Why subsurface drip has become the default

The 2025 guidelines are blunt about it: subsurface irrigation represents a significantly lower risk of human contact and is preferred to surface irrigation. Putting the effluent in the root zone keeps it away from kids, pets and mowers, and cuts surface run-off in long wet spells.

Hunter conditions push the same way. For medium to heavy clays, which the guidelines class as Category 6 soils and which many Hunter blocks sit on, the notes to their sizing table say low-pressure effluent distribution is not advised and drip irrigation of secondary effluent is the preferred method. The guidelines also say surface irrigation designs are inappropriate where rainfall exceeds evaporation for extensive periods and soils may be saturated.

Some councils have written this into policy. Upper Hunter Shire Council’s inspection page says surface irrigation will not be permitted for new systems on blocks under 4,000 m² or in sensitive locations, and lists subsurface irrigation at more than 100 mm below ground level. For a new AWTS, the guidelines make subsurface drip the starting point, and spray needs a site that suits it.

Subsurface systems have their own upkeep. The guidelines’ installation notes call for a disc filter before the sequencing valve, cleaned at each quarterly service, plus a flush valve on the return line, air release valves at high points, and either root-inhibiting drip line or a filter that doses a root inhibitor.

If your approval allows sprinklers

Some older AWTS approvals allow surface sprinklers. If yours does, the OLG’s model approval conditions give a good picture of what councils expect. They are published as a guide for councils rather than law in themselves, so check them against your own approval.

• Low, coarse spray. Where surface irrigation is approved, the model condition calls for sprinklers with a plume of coarse droplets no higher than 0.4 m, on a supply line buried 0.1 m below ground. The guidelines say sprays must not generate aerosols.
• No garden-hose fittings. Irrigation pipework and fittings must not use standard household hose fittings or sprinklers, and must not be able to connect to mains water. That rules out clicking a normal garden sprinkler onto the effluent line.
• Buried lines. All distribution lines must be buried at least 0.1 m below finished ground level.
• No run-off or drift. The system must be installed and run so no effluent runs off or drifts out of the irrigation area.
• Fixed heads, not portable ones. The guidelines say moveable sprinklers are not recommended because of the risk of misuse, damage and hose kinking.

The guidelines also list what makes surface systems risky in practice: mower and UV damage, pets and stock, how easy it is to redirect effluent toward boundaries, drains or vegetable patches, and people retrofitting the wrong hoses and sprays.

Signs, fences, cars and stock

The irrigation area has to be marked and protected, whatever method feeds it.

Signs. The guidelines say signage should indicate at all access points that effluent is being irrigated, and warning signs are required in every area that is surface irrigated. The OLG model condition asks for at least two signs within the irrigation area, complying with AS 1319-1994, with a green background, 20 mm black or white capital lettering and the words RECLAIMED EFFLUENT - NOT FOR DRINKING - AVOID CONTACT. Signs fade and get knocked over, and their condition is on the guidelines’ quarterly checklist.

Fencing or planting. For surface systems, the installation notes say to erect fencing or plant shrubs around the edge of the area to keep out vehicles, livestock, domestic animals and children. The Easy Septic Guide also suggests a low bund, about 15 cm, around an effluent irrigation area to stop stormwater running on and effluent running off.

Cars and stock. The model conditions require the treatment system and irrigation area to be protected from damage by vehicles and stock, because crushing and compaction damage the pipework and the soil. Cessnock City Council’s owner guidance says the same in plain terms: exclude vehicles and large animals from the area above your system. On acreage with stock, a sign alone won’t keep them off.

Nothing built on it. Buildings, driveways, concrete, tennis courts, pools, garden beds, vegetable gardens and large trees are all listed in the model conditions as things that must not be placed in or on the irrigation area. It’s meant to stay a permanent, dedicated area.

Setbacks from boundaries, buildings and water

The 2025 guidelines give ranges for an effluent application area rather than fixed figures: 1.5 to 15 m to property boundaries, 2 to 6 m to buildings, 1.5 to 6 m to drives and paths, 3 to 15 m to pools and recreation areas, 15 to 40 m to farm dams, intermittent creeks and drainage lines, 15 to 100 m to bores and wells, and 50 to 100 m to permanent waterways. They say buffers should be at the upper end of the range for any surface application of effluent, and that subsurface drip of secondary effluent downslope of an upslope boundary may come down to 0.5 m from that boundary.

Many existing approvals predate the 2025 guidelines, having been issued under the 1998 Silver Book they replaced, and older fixed figures still appear in the Easy Septic Guide and on Upper Hunter Shire Council’s inspection page. For surface spray those are 6 m uphill and 3 m downhill of driveways and boundaries, 15 m to dwellings, 3 m to paths and 6 m to pools. For surface drip and subsurface irrigation, 6 m uphill and 3 m downhill of pools, boundaries and buildings.

The setbacks that apply to you are the ones in your system’s design report and approval. Planning a pool, shed or driveway near the irrigation area? Ask council before you commit, and if a second dwelling is on the cards, read our granny flat septic requirements first.

What you can plant, and what you can’t

No food crops. The OLG model conditions say the irrigation area must not be used to grow vegetables or fruit for human consumption, and no effluent from the system may be used for that purpose. NSW Health’s accreditation limits AWTS effluent to garden use. Keep the veggie patch and fruit trees well away and upslope.

Lawn is best. The guidelines say managed lawn gives a high evapotranspiration rate and is recommended best practice for most irrigation areas. Shrubs, ground covers, sedges and grasses growing to 0.5 to 1 m are also suitable.

Keep big trees back. Large trees, big shrubs and species with invasive roots should not be planted on the area. The guidelines’ rule of thumb is to plant large trees at a distance from the irrigation area equal to their expected height.

Choose tolerant plants. The Easy Septic Guide warns that disinfected AWTS effluent can cause chloride toxicity in plants and that many natives don’t cope with high nutrient loads. Ask a local nursery; the guide’s own plant list includes lawn grasses and lomandra.

Mow regularly. Long grass hides ponding and damaged heads.

Moving, extending or changing the irrigation

The OLG model conditions say an on-site system must not discharge onto any land other than its approved application area and by the approved method, and that no alterations or additions to the system are allowed without written approval from council.

Cessnock City Council’s page on unauthorised work lists changing the location of disposal, and changing how treated wastewater is disposed of, as alterations. It says a system approved to dispose underground cannot be changed to surface irrigation, and that installing or altering a system without approval is an offence.

So moving sprinklers outside the approved area or swapping drip line for spray heads needs council’s written approval first. Running a hose off the pump line to the orchard is not an option at all: the guidelines do not allow domestic hoses, and the model conditions bar effluent on food crops. If you’re unsure whether a job counts as an alteration, ask council before the shovel goes in.

Where the area does need to move or grow, the new pipework and drip lines are laid by licensed plumbing and drainage contractors we work with; their NSW licence number appears on every quote. We can do the site assessment, help with the Section 68 paperwork and coordinate the job. If the irrigation pump itself has failed, which is one reason sprinklers stop spraying, replacing it runs $600 to $1,200 installed.

What inspectors and service agents look for

Your quarterly service and council’s periodic audit both look at the irrigation area as closely as the tank.

The NSW Health model service report, which authorised service agents fill in after each visit, has a land application area section asking about surface ponding, run-off, excess plant growth, effluent leaving the premises, and contamination of high-risk areas such as patios, play areas and barbecues. The irrigation pump and the application area are both on the list of items checked at every service.

The OLG guidelines set at least quarterly checks for irrigation systems by a service contractor or agent: flushing the lines, checking air release valves on subsurface systems, checking every sprinkler works on surface systems, and checking the warning signs. For every application area they add an at least annual inspection covering pooling at the surface, even vegetation growth, and the condition of stormwater diversion.

A quick walk-round before a council inspection, or once a season, catches most of it:

• Soggy or smelly patches, or grass that is much greener in one spot
• Sprinkler heads broken, blocked, pointing off the area or spraying too high
• Drip lines exposed by mowing, digging or erosion
• Signs missing, faded or hidden by plants
• Fence down, or stock or vehicle tracks across the area
• Garden beds, sheds or veggies crept onto the zone
• Stormwater from roofs or driveways running onto it

A wet, smelly irrigation area can point to a problem further back: sludge carrying over, an empty chlorinator or a failing pump. Our AWTS servicing covers the whole system for $90 to $150 a visit, and we send the service report to your council after each visit. If the alarm has gone off as well, start with why your AWTS alarm is beeping, or call 0468 278 123.

Frequently Asked Questions

Can I use normal garden sprinklers on my AWTS?

No. The OLG model approval conditions say irrigation pipework and fittings must not use standard household hose fittings or sprinklers, and the guidelines say domestic hoses are not allowed. Where council has approved surface spray, it expects fixed coarse-droplet sprinklers no higher than about 0.4 m on a buried supply line.

Is subsurface or surface irrigation better for an AWTS?

The NSW Office of Local Government’s 2025 guidelines prefer subsurface drip, because it carries much less risk of people touching effluent and less surface run-off. Surface spray is still found on some older systems, but only where council has approved it.

Can I grow vegetables on my AWTS irrigation area?

No. The OLG model conditions prohibit growing vegetables or fruit for human consumption on the irrigation area and using the effluent for that purpose. Lawn, grasses and shrubs up to about a metre are the recommended planting.

Can I move my septic sprinklers to another part of the yard?

Not without council’s written approval. The OLG model conditions bar alterations without it, and Cessnock City Council, for example, lists changing where or how treated effluent is disposed of as altering the system and says altering a system without approval is an offence. Any new pipework should be laid by a licensed plumbing and drainage contractor.

Does my irrigation area need a sign?

Yes. The guidelines require signs at the access points to an irrigation area, and warning signs wherever effluent is surface irrigated. The OLG model condition asks for at least two green AS 1319 signs reading RECLAIMED EFFLUENT - NOT FOR DRINKING - AVOID CONTACT.

How far does the irrigation area have to be from my house and boundary?

It depends on your approval and the irrigation method. The 2025 guidelines give ranges, such as 1.5 to 15 m to boundaries and 2 to 6 m to buildings, with the upper end for surface spray, while many older approvals use fixed figures such as 15 m from a dwelling for spray. Check your design report or ask your council.

Sources and further reading

• NSW Office of Local Government, Onsite Wastewater Management Guidelines (April 2025): subsurface and surface irrigation (sections 5.7.5, 5.7.6, 6.2.9, 6.2.10), buffer ranges (Table 4-2), slope limits, climate, suitable vegetation (6.11), model approval conditions (Appendix 2), installation notes (A4.5.3, A4.5.4) and maintenance checks (Appendix 5).
• NSW Office of Local Government, The Easy Septic Guide: signposting, the 15 cm bund, chloride toxicity, plant list and the older fixed buffer distances.
• NSW Health, Secondary Treatment System Accreditation Guideline: permitted irrigation forms for accredited AWTS effluent, service items and the model service report’s land application area checks.
• Upper Hunter Shire Council, On-site Sewage Management System Inspections: no surface irrigation for new systems on blocks under 4,000 m², and buffer distances by irrigation method.
• Cessnock City Council, Your responsibilities and inspections: keeping vehicles and large animals off the system.
• Cessnock City Council, Unauthorised installation, alteration or operation: changing the disposal location or method is an alteration that needs approval.
• Singleton Council, On-site Sewage Management: AWTS effluent suited to irrigation of lawns or gardens; septic tank effluent must go below ground.