Waste Water Treatment (Greywater & Blackwater)

Goals of Innovation:

To pretreat liquid waste from the home reducing the burdon on the environment.

Description:

Wastewater from the sink, shower, dishwasher and washing machine is filtered and reused beneficially (by live plants) on-site prior to entering the on-site wastewater collection and treatment system. The water from these drain sources is channeled through a trough at floor level running the entire length of 80 feet along the southern side of the house.

The trough is graded from 2 feet deep on one end of the house to 5.5 feet deep on the other end. It has a layer of gravel overlain by one foot of sand and then capped with soil. The soil is located in a raised rock planter, which sits directly in front of the southern windows.

Greywater is discharged from its' source through a filtration box to remove larger particles at the shallow end of the trough. It then travels along the trough, remaining within the gravel layer and providing water to the vegetables planted in the soil above. Overflow runs under the exterior wall and enters the blackwater settling system and ultimately into the drainage field.

The blackwater system pretreats the effluent from the septic tank with the same method as the greywater system before it discharges into the drainfield.

Obstacles:

The initial filter box requires manual cleanout on a weekly basis by the homeowner. This is not a large task but requires periodic attention for proper operation.

This system has the potential to release excess moisture into the living environment, not a big concern in a dryer climate, but here in Tennessee it could require additional management. The humidity is monitored to track this concern. So far, it has not evolved into a problem. Suggested humidity levels for optimum comfort are around 40 - 50%; this home shows levels at 60 - 70%. These levels actually compare to other structures in the area and the homeowners are happy. Levels will continue to be monitored as will the homes' interior building materials, in case any moisture-related issues appear.

A learning curve is required to bring contractors up to speed on this design.

Cost Information:

This system is not expensive to install or maintain. All of the plumbing uses conventional parts that are readily accessible. This home acquires its' water from springs, so no cost is saved by reusing water, the benefits are environmental and aesthetic. The situation would typically be the same for a home that utilizes public water services since most utility companies charge based on water intake rather than disposal. The system would reduce costs associated with irrigation if the alternative was to purchase water from a supplier.

Additional Benefits/Drawbacks:

The ability to grow year-round food without watering requirements is a huge benefit for the homeowners. They grow beautiful tomatoes that brighten the living space and put food on the table.

Related Path Technology Fact Sheet: For additional benefits, drawbacks and cost information, visit the Toolbase Services Path Technology fact sheet at: http://www.toolbase.org/tertiaryT.asp?TrackID=&DocumentID=2137&CategoryID=1002