Septic and on-site wastewater in the Redlands
Updated October 2026
A great deal of the Redlands has no sewer main, and that changes the whole shape of a drain problem. There is no council main to blame, no connection point to argue over and no reimbursement path. The pipe, the tank, the pump and the disposal area are all yours. Redlands Blocked Drains connects you with QBCC-licensed local plumbers who work on drainage and on-site wastewater across the Redlands.
Where the Redlands is not sewered
This comes from Redland City Council's own catchment information, in the council's own terms.
- Russell Island, Macleay Island, Lamb Island and Karragarra Island are unsewered and serviced by on-site wastewater treatment and septic systems. All four.
- Amity Point. The council states that residential areas in Amity are unsewered.
- Dunwich and Point Lookout. The council states that approximately half the urban areas of each are unsewered. It publishes no property-level service map that settles any particular address, so this site will not name a street as sewered or unsewered. A council property search or a service enquiry is how you find out which half you are in.
- The rural south. The council states that rural non-urban properties in the Redland Bay area and in the Native Dog Creek, Serpentine Creek and Upper Tingalpa Creek catchments use septic or on-site systems. In suburb terms that means acreage Redland Bay, Mount Cotton and Sheldon.
Coochiemudlo Island is the exception among the islands. The council states that wastewater from the Coochiemudlo Island population is piped and treated at the Victoria Point treatment plant, so it is sewered. That does not mean every single property on the island is connected, so check your own arrangement rather than assuming.
It is worth knowing that the unsewered status of the four southern bay islands is structural rather than a gap about to be closed. The council lists seven wastewater treatment plants, at Capalaba, Cleveland, Dunwich, Mount Cotton, Point Lookout, Thorneside and Victoria Point. There is no plant on those islands and none at Amity Point. This site publishes no cost or timeline for sewering the islands, because the figures that circulate are neither current nor a council commitment.
Septic tank or treatment system
The two are often spoken of together and they behave quite differently.
A conventional septic tank separates solids and lets the liquid go out to a soil absorption trench or bed. It has no moving parts, it relies entirely on the ground to do the final treatment, and it fails when the solids are never pumped out or when the trenches become saturated or clogged.
An aerated or advanced on-site treatment system pumps air through the effluent, uses bacteria to treat it, and then discharges treated water to a sub-surface irrigation field. It has a blower, pumps, alarms and often a chlorinator, so it needs power and periodic servicing, and it fails for mechanical reasons as well as biological ones.
Which you have determines what a back-up means. A gurgling, slow house on a septic tank usually points at a full tank or failed trenches. The same symptoms on a treatment system might be a tripped blower, a seized pump, a float switch or a blocked irrigation line.
What backs up, and what to check
- The tank is full. The most common cause, and the cheapest to rule out. Pump outs are routine maintenance, not a repair.
- The disposal area is saturated. After a wet summer week on the bay islands or heavy rain on a flat block, the ground simply cannot take any more, and the system backs up from the far end. Wet, smelly or unusually green ground over the trenches or irrigation field is the tell.
- A pump or blower has failed. On a treatment system this stops the process. Many systems have an alarm, and many alarms have been silenced by somebody at some point.
- Roots or a collapse in the line to the tank. Ordinary drain work, and a camera and jetter handle it the same way as anywhere else.
- Too much water at once. A long guest weekend, a leaking toilet cistern or a washing machine running all day will overload a system sized for normal use.
- The wrong things going in. Wipes, fats, bleach in quantity and heavy disinfectant all affect a biological system.
Who can work on it, and what the council requires
On-site systems in Redland City must meet plumbing, health and environmental standards, and council approval applies to installing or altering one. That is the honest level of detail. If someone tells you a specific type of system is mandatory on your island, ask them to show you the council document, because this site has not been able to verify that claim and will not repeat it.
Plumbing and drainage work in Queensland requires a QBCC licence at any value, which is stricter than the general building work threshold for other building work. Ask for the licence number and check it on the QBCC register before signing. Some plumbing and drainage work is notifiable work, which the licensed plumber registers with the QBCC and gives you a copy of, and the QBCC's categories of notifiable work page sets out what that covers. Servicing contracts on aerated systems are a separate arrangement, often with the manufacturer or an authorised servicing agent.
Getting a trade to an island property
This is the part worth being straight about. A plumber with a jetter, a camera reel or an excavator reaches Russell, Macleay, Lamb and Karragarra islands on a booked vehicle barge from Weinam Creek at Redland Bay, and reaches Dunwich, Amity Point and Point Lookout on the vehicle barge from Toondah Harbour at Cleveland, which takes about 45 to 50 minutes each way. The passenger ferries do not carry work vehicles, vehicles have to be booked ahead, and services can run late at low water on spring tides. Vehicle access permits also apply on North Stradbroke Island.
So an island job is a planned job. We will call you back promptly and tell you honestly whether a plumber can get to you and when, and some of the trades who work the islands live on them, which is often the fastest answer. Pump out services operate on the islands as well, and for a full tank that is the call to make rather than a mainland plumber.
For current barge fares and bookings, go to the operator at SeaLink. This site states no fare, because a state subsidy, an operator discount and a fuel surcharge all apply and the figures move.
What it costs
On-site wastewater work is priced separately from drain clearing, because it is different work. A pump out is a scheduled service with its own rate. A pump, blower or float replacement is a parts and labour job. Trench or irrigation field remediation is excavation work and is quoted on the site. Clearing a blocked line into the tank is ordinary drain work and sits in the usual $150 to $400 range, with camera and jetting as per the cost guide. On the islands, the crossing is a line item the plumber will quote.
Frequently asked questions
How often should a septic tank be pumped out?
It depends on tank size, household size and what goes in, and the servicing schedule for your system is the guide. If it has never been done, that is the first thing to arrange.
Is my back-up a blocked drain or the system?
If the house is backing up and the ground over the tank or disposal area is wet, smelly or unusually green, suspect the system. If the ground is dry and one branch is slow, suspect the line. A plumber can tell quickly on site.
Can I put a new system in myself?
No. Installing or altering an on-site sewerage facility requires council approval, and the plumbing and drainage work requires a QBCC-licensed plumber.
What about the stormwater on an unsewered block?
Separate system, separate problem. Stormwater still has to go somewhere lawful, and on a block with an on-site disposal area it matters even more that rainwater is kept off the trenches. See the blocked stormwater page.
Will the islands ever be sewered?
Not a question this site will answer with a number or a date. Community groups have campaigned on it and the council has looked at it, but there is no commitment that would be honest to quote here.