Septic Systems and Composting Toilets

Written by d.m. gutierrez
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Septic Systems and Composting Toilets
A composting toilet turns human waste and other organic materials into compost. (toy toilet image by Wayne Abraham from

Septic tanks and composting toilets are two on-site waste management options for homeowners who don't have access to municipal sewage systems. The traditional septic tank option requires expensive installation and adequate space for a buried tank and drain fields that extend well out into the homeowner's property. A composting toilet is a self-contained unit that turns solid waste into manageable compost. Each has its advantages, disadvantages and specific maintenance requirements. An alternative to both options is the incinerating toilet.

Septic Systems

A septic system uses plumbing from the residence that leads to an underground concrete tank. The tank empties out into drain fields on the property. The liquid waste that enters the septic tank from the house stays in the tank until new waste comes in. This water influx forces the existing liquid to stream out into the drain fields (also called leach fields) where it percolates through sand and gravel and is purified. The solid waste sinks to the bottom of the septic tank and must be pumped out every so often for the waste water management to continue working properly.

Composting Toilets

Composting toilets are used most often in areas where there is not enough space for a traditional septic system or the soil is not suitable for drain fields. A composting toilet uses less water than a conventional septic system, so they are often used in coastal areas where fresh water is in short supply. The liquid and solid products of a composting toilet can sometimes be disposed of on site, but more often need to be removed by certified experts. Composting toilets work by diverting liquid and solid wastes into treatment tanks where solids are broken down by biological agents into compost, and liquid waste is either evaporated or drained off. This requires a great deal more inspection and maintenance by the homeowner than a septic tank system.


A septic system requires a pump-out of its solid waste every three to five years, according to the Environmental Protection Agency (EPA). A composting toilet needs more frequent monitoring and tending. Composting toilets need fans, heaters and mixers to keep the compost aerated at a temperature above 15.6 degrees Celsius. It must become neither too dry nor too wet. In perfect conditions, compost from composting toilets can be buried at a six-inch depth in the yard, but usually an annual or biannual compost removal by a professional is carried out.


A properly maintained septic system can last for over 40 years. Though the initial cost to install it is high, a septic system costs relatively little to maintain. Average septic tank pump-outs run less than £130 every few years. Composting toilets cost less to install, and do not use the high volume of water needed by septic tank systems. They do need electricity to run fans, heaters and aerators, which septic systems do not need. Properly maintained composting toilets produce treated waste that can be handled safely by homeowners, while septic systems must be emptied by sewage experts. Composting toilets work well in areas too small or lacking the soil drainage capacity essential to septic tank systems.


One alternative to the septic tank and composting toilet is the incinerating toilet. This type of waste management system is simple to install and much easier to maintain. Often used in areas where the space necessary for septic tanks and composting toilets is limited (such as the beach or a cliffside home), an incinerating toilet needs only access to electricity or gas, and ventilation to the outside. An incinerating toilet burns up solid and liquid waste, leaving nothing but sterile ash that can be easily tossed out.

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