If you have a customer who would like to open up a spa or is already offering spa services and is served by a septic system, there are numerous concerns to be addressed in the design and management of the system.

Previously, it was assumed spa wastewater may contain hazardous materials, but recent studies have not shown this to be true — although the typical chemicals used in a spa may create a challenging environment for the necessary bacteria in a septic tank and soil treatment system. The addition of these chemicals may result in septic tank effluent that does not meet the definition of domestic wastewater. If this wastewater is applied to a soil treatment system the life of the system will likely be reduced.

1. Types of services: Many spas will offer a wide range of services. Each of these has the potential to impact flow, strength and toxics. A detailed survey should be completed which quantifies the number of stations, customers and employees at the facility per day. Commercial survey forms can be found at: http://www.onsiteconsortium.org/awtschecklists.html (see 7.15 Beauty Shops). 

• Hair services include cuts, coloring, perms, relaxers
• Manicure and pedicures
• Messages – oil, mud
• Facials
• Waxing
• Showers or hot tubs
• Food or beverage service
• Restrooms (customers and employees)

2. Current or proposed cleaning practices that will impact the septic system:

• Drain cleaners
• Floor drain waste
• Degreasers
• In-house laundry

Recommendations

• Install a water meter or another device to track daily flow. If it is a new facility, determine water pressure (gallons per minute) of well/water supply and have owner estimate usage per customer for each activity above.
• Sample the effluent from the current system for biochemical oxygen demand, total suspended solids and fat, oil and grease and compare to typical domestic levels.
• If there is a water treatment device, be sure it routes out of the septic system.  
• Discuss the products used in the facility for coloring, perms and relaxing, and encourage natural/biodegradable products. If any are strong disinfectants consider routing one sink to a holding tank.
• Recommend a UPC-approved hair trap for salons.
• Install a washing machine lint filter if laundry will be washed on site.
• Add additional tank capacity and a commercial size effluent screen to try to catch small hair and clay particles (if mud is used).
• Recommend the spa limit the use of petroleum based oils and lotions, as they can be toxic to microbes in the system.
• Limit the use of mud as the small silt and clay particles may pass through the septic tank and plug the soil treatment system. 
• Be sure no chemically treated water from hot tubs is entering the system.
• If food or beverage is provided discuss the extent — for example, are they dumping a significant amount of unused coffee each day?
• A maintenance contract should be in place with a licensed onsite professional to assure the proper operation and maintenance of the treatment system. The contract should include sampling and a minimum of annual checks unless annual evaluations indicate a long time period is warrantied.

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About the author: Sara Heger, Ph.D., is an engineer, researcher and instructor in the Onsite Sewage Treatment Program in the Water Resources Center at the University of Minnesota. She presents at many local and national training events regarding the design, installation, and management of septic systems and related research. Heger is education chair of the Minnesota Onsite Wastewater Association and the National Onsite Wastewater Recycling Association, and she serves on the NSF International Committee on Wastewater Treatment Systems. Ask Heger questions about septic system maintenance and operation by sending an email to kim.peterson@colepublishing.com.