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CONSIDERATIONS:
Composting toilets are lawful in Austin provided the units are approved by the National Sanitation Foundation (NSF) or engineered by a registered Professional Engineer.
Austin presently composts sewage waste derived from its central wastewater system. The composted product is marketed as a landscape fertilizer called Dillo Dirt. For this reason, it may be difficult to justify the extra expense and maintenance needs of a composting toilet in order to gain compost when a city sewer line is available. Additionally, the low volume of water required to be used by toilets in Austin (1.6 GPF) makes the water savings from using a waterless toilet quite low.
If a home does not have central wastewater services, a composting toilet may be practical. Coupled with a sub-surface greywater irrigation system, the composting toilet can avoid the installation of a blackwater septic system. Although kitchen sink wastewater is defined as blackwater along with toilet wastewater, the Austin-Travis County Health Department may permit the discharge of kitchen wastewater with greywater in a sub-surface irrigating system if the site conditions are suitable.
There are commercial products available that range in cost from $1000 for simpler units to $10,000+ for fully integrative wastewater/composting systems. In areas where these systems can supplant large investments in septic systems, they are cost competitive.
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Implementation Issues |
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| Composting Toilets |  |
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Satisfactory |
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Satisfactory in most conditions |
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Satisfactory in Limited Conditions |
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Unsatisfactory or Difficult |
GUIDELINES
The separate storage chamber needs to be accessible to remove the compost. This is a design consideration that must be addressed in a home that may typically use a slab floor on a flat site.
Some split units may flush the commode with a small amount of water or foam.
Several manufacturers offer heaters to accelerate the decomposition process in cold temperatures. There are different sized models available to meet the needs of various sized households.
Professional engineering services are generally unnecessary unless unusual installation or size requirements must be met.
To use solar energy to help in the decomposition process (by heating the wastes), an engineered system would be needed.
On-Site Inc.
8105 Perry Hwy.
Pittsburgh, PA 15237
(412) 366-4260
primarily consulting and design
Biolet USA, Inc.
Water Conservation Systems
Damonville Square
Concord, MA 01742
(508) 369-3951
distributor for imported models, NSF approved
Sun-Mar Corporation
Bio-Sun Systems Inc.
5035 N. Service Rd., C2
Burlington, Ont. Can. L7L 2G5
(905) 332-1314
manufacturer, NSF approved
Bio-Sun Systems, Inc.
Box 134A, RD #2
Millerton, PA 16936
(800) 847-8840
not NSF approved
Clivus Multrum Inc.
15 Union Street
Lawrence, MA 01840
Tel 1- 800-4-clivus
1-978-725-5591
Fax 1-978-557-9658
manufacturer, NSF approved
On-Site Insight, free newsletter re: on-site wastewater treatment
Write: Texas Water Resources Institute
Texas A & M University
301 Scoates
College Station, Texas 77843
(409) 845-1851
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Sustainable Building Sourcebook web version copyright Sustainable Sources 1994-1999.