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Residential dishwashing machines and their possible effects on septic systems are explained in this article. Will the discharge from a home dishwashing machine into a private septic system harm the septic tank or drainfields? What detergents are best to use in a home dishwasher to minimize impact on the septic system and the environment. How can we reduce the impact of a dishwasher on a septic system - should we install a separate drywell? This document explains how to extend the life of the septic system by being careful about what goes into it. Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman. A Guide to Home DISHWASHER Machines - and Septic SystemsDoes a dishwasher water volume overload and harm the septic system?
Dishwasher & Laundry Detergents Containing Phosphates & Surfactants May Contaminate the EnvironmentDoes dishwasher detergent or dish soap harm the septic tank or septic system drainfield?
However many if not most dishwasher detergents contain phosphates or nonylphenol ethoxylate surfactants. Surfactants are what make detergents effective in lifting soil particles off of a surface (a dish in the dishwasher or a shirt in the washing machine). Dishwasher detergents do not make a high level of suds inside the dishwashing machine. If you've ever made the mistake of putting normal dish soap into a dishwasher (as did this author) you know what a disaster will ensue - with sudsy soap overflowing out of the dishwasher and across the floor. Dishwashers rely on surfactants, high water temperature, and time spent spraying across the dishwasher contents to clean them. Even if they don't kill off your septic tank or drainfield bacteria, surfactants and phosphates that run through a dishwasher ultimately enter ground water and surface water may also become contaminated. Surfactants in dishwasher detergents (and from any source) are toxic to fish, basically suffocating them by interfering with the ability of the fish's gills to absorb oxygen from water. Phosphates in dishwasher detergents pass through the septic system (or municipal wastewater treatment system) and enter surface water causing very high growth rates of algae. The algae growth, in turn, suffocates fish and other life in rivers, streams, lakes, and ponds. The rapidly growing "dead zones" at the edges of major water bodies around coastal areas of the U.S. and other countries are blamed on surface runoff that contains phosphates, (probably largely from agricultural use). According to Cliff Davies, a U.S. EPA engineer reported in the New York Times the level of phosphates in dishwasher detergent has been significantly reduced since the 1970's. But Mr. Davies was unable to identify specific dishwasher detergent products or brands that were high in surfactants or phosphates, and the Times article reported that the U.S. EPA "Design for the Environment Program" which he administers does not track products that are problematic. The EPA does, however, list dishwasher detergent products whose manufacturers report to the EPA that they use the safest chemicals. The EPA does not perform tests to confirm the accuracy of product claims. In sum, consumers who want to minimize their contribution to environmental pollutants by their choice of dishwasher or washing machine cleaning products may want to purchase products listed by the EPA's "Design for the Environment Program" but the listing designation does not appear to be supported by independent testing nor publicly available data. As of February 2009 it's the best we've got. Laundry detergents & soaps used in washing machines & dishwashers are discussed separately at WASHING MACHINES & SEPTIC SYSTEMS Install a Drywell to Handle Dishwasher Drainage to Protect the Drainfields from OverloadOne option is to install a separate graywater system (greywater) or drywell to receive water from the dishwasher. If you are considering this step, consider connecting both dishwasher and clothes washer to a common drywell. At some properties with very limited septic capacity, a large drywell may be installed to handle additional gray water from other building fixtures such as sinks and showers. See DRYWELL DESIGN & USES for additional information. Citation of this article by reference to this website and brief quotation for the sole purpose of review are permitted. Use of this information at other websites, in books or pamphlets for sale is reserved to the author. Technical review by industry experts has been performed and comments from readers are welcomed. Contributors are listed at the end of each article. This article is a section of our online book SEPTIC INSPECTION & TEST GUIDE whose chapters are shown at the left of this page. Citation of this article by reference to this website and brief quotation for the sole purpose of review are permitted. Use of this information at other websites, in books or pamphlets for sale is reserved to the author. Technical review by industry experts has been performed and comments from readers are welcomed. Contributors are listed at the end of each article. Frequently Asked Questions (FAQs)... Ask a Question or Search InspectApediaQuestions & answers or comments about the effects of a dishwasher on private septic systems Ask a Question or Enter Search Terms in the InspectApedia search box just below. Technical Reviewers & ReferencesRelated Topics, found near the top of this page suggest articles closely related to this one.
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