Austin Water is piloting an innovative and integrated on-site blackwater reuse facility at the City of Austin’s new Permitting and Development Center to promote and advance decentralized reuse goals contained in Austin Water’s 100-year Water Forward Plan.


Read some of the most frequently asked questions about OSCAR and CLARA - the future of water management.


What is CLARA and why was it installed?

CLARA or Closed-loop Advanced Reclaimed Assembly is an on-site blackwater reuse system that collects up to 5,000 gallons per day of wastewater from the building’s sewers, treats it using advanced membrane technology, and then recycles the clean water back to the building to flush toilets and urinals. The water can be used repeatedly for this purpose.

With a rapidly growing city and a changing climate, Austin Water has led the effort to develop Water Forward a water plan for the next century. The goal of the Water Forward plan is to ensure a diversified, sustainable, and resilient water future, with strong emphasis on water conservation. This plan includes a range of strategies including on-site water reuse. In addition to reducing the potable water demand of the site, Austin Water piloted CLARA as a demonstration project to encourage new developments in the city to implement onsite reuse.

Where can I learn more about the treatment process in CLARA?

View the case study document for a description of the treatment process.

How much did it cost?

The cost to design and construct CLARA was about 1.7 million dollars. This does not include operation and maintenance costs.

What were the challenges in building CLARA? What lessons were learned in piloting CLARA?

As a first-of-its-kind project in the City of Austin, it was critical to hold in-person meetings with city staff to explain the project and its purpose. Getting the blackwater reuse system through the city’s development review process was no small task, with hang-ups at multiple stages of review and approval. However, as a result of this project and the expectation of more to come, the city will be requiring backflow prevention plans to be submitted earlier on in the development review process. This will facilitate fewer construction and building occupancy disruptions while ensuring adequate cross connection prevention measures between the potable and non-potable water supplies. Early consultation with the city’s backflow prevention group for this project, for example, resulted in a time and water saving dye injection system that will allow cross connection testing to occur without shutting the building down to drain water lines.

How does CLARA supply water to only toilets and urinals?

The building is dual plumbed, with separate potable and non-potable piping systems. The potable piping delivers to water drinking fountains and sinks. Non-potable water from CLARA is piped to the toilets and urinals. There is a potable makeup water supply for CLARA in case the treatment system needs to go offline for maintenance. Cross-connection and backflow prevention measures are put in place to keep the potable and non-potable systems separate. Additionally, non-potable pipes are colored purple for easy identification. Signs are also provided where non-potable water is in use, namely the toilets and urinals.

Is CLARA water used in irrigation?

CLARA water is only piped to the toilets in the building. Although CLARA water is not used for irrigation at the building, irrigation is an allowed end use for non-potable water supply from blackwater reuse systems.

Is CLARA water safe?

Yes, CLARA is designed and regulated per the requirements of Title 30 Texas Administrative Code, Chapter 210 for Type I reuse which can be used for toilet and urinal flushing.  These regulations lay out monitoring requirements for systems like CLARA to ensure water quality requirements are met on an ongoing basis. The minimum sampling frequency requirement for Type I reclaimed water is twice per week. However, since this is a pilot system, Austin Water operators will initially collect samples daily for additional data on treatment capabilities and operational requirements.

Is it safe to drink the building’s tap water?

Yes, the building’s drinking water fountains and sink faucets are all supplied by Austin Water’s potable water supply and therefore completely safe to drink from. CLARA’s non-potable water is separately piped to the building’s toilets and urinals. Austin Water will monitor the systems regularly to prevent any potential cross connection between the potable and non-potable systems.

Will CLARA emit offensive odors?

CLARA was designed with an odor control system to prevent odors from escaping during normal operations. The system utilizes an in-line fan to pull air/gases from the headspace of the bioreactors and trash tanks. This air is discharged through a container of activated carbon which will remove odorous compounds.

Can CLARA overflow into the pedestrian areas on the PDC site?

CLARA is designed with overflow piping to the City’s sewer mains. Any backups in the treatment system will cause wastewater to overflow into the City’s sewer mains and not into pedestrian areas.

How long does the treatment process take?

Once the effluent is pumped into the pre-anoxic chamber, CLARA takes about 32 hours to treat the sewage and make non-potable water available for flushing toilets.

How much space does CLARA take?

CLARA occupies an area of about 800 sq. ft.

Who manufactured and installed CLARA?

Many entities were involved in the design, manufacturing and installation of CLARA.




Who is responsible for operating and maintaining CLARA?

CLARA will be operated and maintained by Austin Water’s certified wastewater treatment plant operators. The operators will receive special training in the operation of CLARA by the design engineer and manufacturer at the time of commissioning. The design engineer is also required to provide an operations and maintenance manual that includes resources on safety, the use of the equipment and control, recommended maintenance frequencies, troubleshooting, and process optimization.



What is OSCAR and why was it installed?

OSCAR or On-site Collection and Reuse is a rainwater harvesting and air-conditioning condensate collection system that can collect up to 40,000 gallons of water. The collected water is filtered and then stored in tanks to reuse for outdoor landscaping.

With a rapidly growing city and a changing climate, Austin Water has led the effort to develop Water Forward a water plan for the next century. The goal of the Water Forward plan is to ensure a diversified, sustainable, and resilient water future, with strong emphasis on water conservation. The plan includes a range of strategies including on-site water reuse. OSCAR collects rainwater and A/C condensate to meet the building’s non-potable irrigation demand with a non-potable source. This fit-for-purpose approach conserves drinking water, saves energy and increases resilience of the site and the city by utilizing a locally available water source.

Where can I learn more about the treatment process?

View the case study document to learn more about the treatment process.

How much does OSCAR cost?

The cost to design and construct OSCAR was about $625,000. This does not include operation and maintenance costs.

Who is responsible for operating and maintaining OSCAR?

OSCAR is operated and maintained by a third-party facility management contractor. Operations and maintenance needs for OSCAR are low and include basic leaf and debris clearing in the filters and gutters, and the occasional maintenance of pumps.

Who manufactured and installed OSCAR?

OSCAR is a RainFlo Collection System with Graf XXL filters. The system was installed by RYAN Companies, the design builders for the entire PDC project.

Why are you collecting both A/C condensate and rainwater?

Central Texas weather patterns alternate between long dry periods that are punctuated by short periods of intense rainfall. In the absence of massive and expensive storage infrastructure, rainwater may not be available when it is needed the most. A/C condensate is a readily available and relatively clean on-site water supply that yields high volumes in the summer when rainwater may be in short supply and irrigation demands are high. A/C condensate is also easy to plumb for collection. Both water sources need minimal treatment to be suitable for outdoor irrigation use making A/C condensate a good companion source to be coupled with rainwater to ensure a continuous on-site water supply for irrigation demands.