There are many alternatives available to the conventional water based toilet and leach field approach to human waste and wastewater. However, if you want to build a house with plumbing in Vermont, not all of them will be able to meet the state’s (VT Agency of Natural Resources) wastewater rules. At this point, all new residences need to meet these rules. There are two kinds of more ecologically sustainable or “green” systems that have been approved by the state. These are composting toilets and constructed wetlands.
Composting Toilet
What is it?
A composting toilet is a dry toilet. A ‘flush’ in a composting toilet usually consists of adding a cup full of wood shavings, chopped straw or leaves. The waste usually ends up in a bin in the basement of the house where it composts. There are several brands of manufactured composting toilets. Some have baffles which make sure that the newest waste and the oldest waste don’t mix. This assures that the end product is more thoroughly composted. Some toilets have small fans which run continuously to maintain proper air flow for decomposition. Some toilets have small electric heaters to keep the ‘compost’ warmer than the ambient temperature and to speed up decomposition. Composting toilets for a single family house can vary in expense from $2,000 to $7,000 depending on size and design features.
Permitting Issues
The end product of a composting toilet is, ideally, dark and soil like, just like a garden compost pile, and is usually manually emptied out with a shovel. The state, however, does not consider the end product of a composting toilet to be compost. Since there might still be some viruses in the end product, the product from a composting toilet is required to be buried more than 6” deep in the ground and not used as fertilizer for food crops. A composting toilet does not require a special review process to be permitted.
Constructed Wetland
What is it?
A constructed wetland is an artificial wetland which is constructed to pre-treat the effluent from the septic tank before it goes to the leach field. In Vermont, these are constructed so that water never rises above the surface. The wetland plants are typically planted in a bed of compost. Below the compost is a layer of gravel. Perforated pipes disperse the effluent into the gravel so that the plant roots can feed on it. Some systems use a patented aeration system to enhance wastewater treatment. Often, in the summer, there is no effluent from the wetland. When there is, it is pumped to a leach field.
Permitting Issues
An aerated wetland system has been recently approved by the state on a pilot basis. This kind of system can now be designed into a project without an additional permitting process.
Project Cost
A quality composting toilet for a single family house can cost $2,000 to $7,000 more than a conventional toilet. A composting toilet can generally enable you to reduce the size of the leach field by 25%. This might save you up to a few thousand dollars. The cost of a constructed wetland is in the $10,000 range and is comparable in cost to a mechanical pre-treatment unit. It also offers the same advantage of a mechanical unit by possibly reducing the size of the leach field. Generally, though, the reductions in leach field size gained by using alternative systems do not offset the increased costs of the alternative systems themselves.
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FAQ’s
If I have a property that doesn’t have enough septic capacity, are there any alternative “green” systems I can use to allow me to build a house?
Possibly. At this time, a building constructed with composting toilets and without any flush toilets can receive a 25% reduction in leach field size as compared to a building with flush toilets.
There are several types of pre-treatment units available for pre-treating the effluent that comes out of the septic tank before it goes to the leach field. In some cases these can increase the septic capacity of the property. However, they often do not help much on properties with very poor soils for wastewater disposal.
If I use a composting toilet or other “green” system, do I still need a leach field?
In almost all cases, some form of leach field will be required. There are no alternative technologies currently approved in Vermont that are allowed to be used without a leach field.
What about a composting toilet and a pipe which drains the greywater into the ground?
If a composting toilet is used, a reduced sized leach field must still be designed and constructed to handle the greywater.
Will a composting toilet or constructed wetland save me money?
Not generally. A composting toilet can enable you to reduce the size of the leach field by 25%. This might save you up to a few thousand dollars. On the other hand, a composting toilet can cost up to $7,000 more than a conventional toilet.
A constructed wetland, when approved, can be used like a mechanical pre-treatment unit (see definitions page) and, in some cases, can allow you to reduce the size of your leach field. The cost of the wetland is comparable to the mechanical unit. However, the cost of any of the pre-treatment units will likely be greater than the savings from reducing the size of the leach field.
Go to the Definitions page for more information.
Information provided on this website is not to be construed as professional advice. Please call us or email us about your unique project.
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