Existing CWMS customers

• We will manage and treat your wastewater
• We will maintain and service the pipes that are external to your property
• We will facilitate for you to have your septic tank pumped out as required to manage the solids entering the network

• When you receive a letter from the contractor, call and arrange a time for them to pump your tank
• Ensure the tank lid is exposed at the agreed time
• Use septic tank friendly chemicals
• Don’t flush wipes or other items
• Minimise fats and oils you put down your drains

Several different fees and charges are associated with existing and new connections to CWMS. Residential customers pay an initial connection fee and an annual service charge.

See our schedule of fees and charges(PDF, 423KB)

In accordance with the legislative requirements the City of Onkaparinga has also published a customer charter for all CWMS customers and a complaints and resolutions procedure. See below.

Customer charter(PDF, 618KB)

Complaints and resolutions procedure(PDF, 317KB)

If you are experiencing financial difficulties and are unable to pay your account by the due date you are urged to contact council as soon as possible to discuss you individual situation. If you are a residential customer you may be eligible to apply for the hardship program.

Hardship policy(PDF, 165KB)

If you are experiencing hardship and would like to apply for the hardship program please contact council.

To ensure your septic tank works properly the follow simple steps can help.

• Don’t overload the system hydraulically – this can cause odour issues to you and your neighbours, instead of doing 5 loads of washing in one day try to spread them out throughout the week.
• Only use septic tank friendly chemicals and even then use them sparingly.  Anything that is going down your drains can impact the bacteria living in the septic tank.  Unhappy bacteria can cause odours.
• Think about what you flush.  Only flush toilet paper! Products marked as flushable wipes aren’t septic tank friendly .  They don’t breakdown in tanks and can lead to numerous problems and out of pocket expenses.  If we see these in your tank you may need to pump the tank out at your own cost.
• Avoid putting food scraps down the sink – foods, fats and oils have the potential to block up the system put them in the bin instead

Only residential wastewater is permitted to be discharge to CWMS without prior agreement.

These items are prohibited and must not be directed to your septic tank or CWMS connection:

• Stormwater including roof and rainwater tank overflow and surface drainage waters
• Backwash from a swimming pool or spa
• Sanitary napkins, liners, clothing and plastic material
• Trade waste including wastewater contaminated with substances such as grease oils, solid and chemicals
• Petrol or other flammable or explosive substances whether solid, liquid or gas
• Medical waste and sharps

If you have an overflow or blockage, locate your boundary connection point (IP) and remove the cover. 

If there is no water flow observed through the IP when you turn a tap on in your house the blockage is most likely on your property.  Please contact a licensed plumber to clear the blockage. 

If water is filled the IP, the blockage is most likely in council’s drain. Please contact council to arrange for an assessment.

Septic tanks work by the bacteria breakdown of sewerage.  If the bacteria are out of balance there can be an odour produced – this is why it is common to have some odour from a new septic tank.  To minimise any odours coming from your tank you can take the following simple steps:

• Don’t overload the system hydraulically – this can cause odour issues to you and your neighbours, instead of doing 5 loads of washing in one day try to spread them out throughout the week.
• Only use septic tank friendly chemicals and even then use them sparingly.  Anything that is going down your drains can impact the bacteria living in the septic tank.  Unhappy bacteria can cause odours.
• Think about what you flush.  Only flush toilet paper!
• Products marked as flushable wipes aren’t septic tank friendly – if we see these in your tank you may need to pump the tank out at your own cost.
• Proprietary products are available from hardware stores that claim to help balance the septic tank’s environment to help support the good bacteria to grow.

Council manages the de-sludging of the septic tanks connected to the CWMS to ensure the amount of solids entering the network are managed appropriately.  When your tank is due for de-sludging you will receive a letter from Council’s contractor you will need to call them to arrange a suitable time for them to service your property. 

If you feel your septic tank is overdue for a pump out please contact the CWMS Coordinator.

If you have any feedback in regards to your experience in getting your septic tank desludged please submit a customer request.

The septic tank is a private piece of infrastructure. Council’s Environmental Health team may be able to help in an approximate location, however you will need to locate and expose the lid for any pump outs or any other reason. It is strongly recommended (and required for newer approvals) for septic tanks to be fitted with risers to bring them to surface – that way you will never have to locate or dig it out again.

There are several reasons you may need to replace the septic tank. Any alterations require an approval which is issued through council’s Environmental Health team. 

Visit our Wastewater management page for more information. 

See: I would like to connect

No structures can be built over a service easement.

These may include but are not limited to dwellings, dwelling extensions, industrial buildings, sheds (outbuildings), decks, concrete slabs, retaining walls and swimming pools. All infrastructure/assets must remain clear and readily accessible.

The Water Industry Act contains provisions that makes it an offence to build any structure over water industry infrastructure or associated land regardless of the presence of an easement.

Yes but think about what plants first!

Many plants have the potential to cause problems for the pipes buried underneath. Trees, in particular, have extensive root systems that can infiltrate pipes. Tree roots seek out moisture and nutrients which are both contained in drainage and sewerage pipes.

The Water Industry Regulations include a number of plants that are prohibited within a certain distance of sewerage infrastructure. Ultimately this has potential to damage both public and private infrastructure and can be disruptive and expensive for the home owner.

There are a number of plants that can safely be planted on and near an easement that won’t impact the drainage system. In general, groundcovers, climbers, grasses and small shrubs do not have deep root systems that can damage pipes.

Generally if not urgent, Council will notify the property owner of their intent to access the easement prior to works.

Urgent access usually only occurs in emergency situations where immediate action is required. In these circumstances notification may not be possible but all efforts will be made to discuss the situation with you.

Due to the age of the infrastructure unfortunately not all drains associated with CWMS are identified on Certificates of title.  However, as an acknowledgement of the essential nature of this infrastructure the Water Industry Act provides protection to these assets and generally it should be treated as if an easement exists (see other FAQs).

Further specific information can be discussed with the CWMS Coordinator.

Several different fees and charges are associated with existing and new connections to CWMS.

Non-residential customers are subject to a unit charge which is determined in accordance with the CWMS Property Units Code and may be subject to Trade Waste Charges based on the quality of the effluent discharged. 

For all current fees and charges see our Schedule of Fees and Charges(PDF, 423KB)

In accordance with the legislative requirements the City of Onkaparinga has also published a customer charter for all CWMS customers and a complaints and resolutions procedure. See below.

Customer charter(PDF, 618KB)

Complaints and resolutions procedure(PDF, 317KB)

We apply a methodology used by councils across South Australia that seeks to equitably share the costs based on a user pays approach. A copy of this methodology is available from www.onkaparingacity.com

Community Waste Management System (CWMS) fees are determined by dividing the total cost of operating the network by the number of connected properties. The cost to each single residential premises is the same.  However, as non-residential properties can produce significantly more wastewater than a household, they may be counted as more than one property unit.

It is not always practical to measure actual wastewater volumes discharged from a business, so the methodology considers the type and intensity of the business activity to determine the number of unit charges that should apply.

This information is best captured via questionnaire. However, we may also cross reference other sources of information such as liquor license details and development approval conditions to determine the appropriate unit numbers.

Completing the questionnaire will allow us to review the current unit charges and ensure that they are applied appropriately.

If your property is tenanted you may need to speak with your tenant to complete the questionnaire.

It is not uncommon for businesses to make changes to their operations over time.  A regular questionnaire of the non-residential connections is the best way to ensure that charges are fair and equitable.

While the questionnaire may result in the unit charge numbers for some businesses increasing or decreasing, we anticipate that for most connections there will be no change.   

If we do not receive a response, the CWMS Coordinator will determine if an inspection is required to undertake the review of the unit charges.  Other information sources, such as liquor license details, development approval conditions, may also be used to determine a suitable unit charge.  

As the CWMS levy is an annual charge, any changes arising from the questionnaire will be implemented next financial year (2025-26).  

We envisage a questionnaire, or similar information gathering exercise, will be undertaken approximately every three years to ensure that charges are current.

If your business changes significantly between questionnaires, it is recommended that you contact the CWMS coordinator to discuss the changes and if they will impact the number of units charged.

Since Council’s decision last year to retain our water assets we have been working to improve efficiencies and reduce operating costs. This has included discussions with our CWMS contractor, investigations into solar to reduce energy costs and pursuing opportunities for external funding.

No. The questionnaire specifically relates to setting of CWMS charges for non-residential properties. The CWMS petition relates to the future ownership and management of the CWMS networks.

Further information on the CWMS petition is available from www.yoursay.onkaparinga.sa.gov.au.

It is likely that Council records indicate that your property while residential includes a non-residential component, this may tourist accommodation or a home based business.  

Please contact: Cassie O’Connor, CWMS Coordinator via CWMS@onkaparinga.sa.gov.au or (08) 8384 0666.