California greywater regulations and design

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All countries and states have specific requirements pertaining to greywater use and reuse. This page provides information pertaining to California looking at some of the history of greywater in California, current regulations and then presenting a method for designing a greywater system that is appropriate for use in California.

General information

Graywater policies vary around the world and within the country, Table 1 shows several water quality constituents of concern and each countries guidelines or regulations on the constituents. The United States has some of the most stringent requirements, with California having the first graywater code in the nation ^[1]. California’s code has up until 2009, been very restrictive and in most circumstances made it infeasible to install a permitted system. On August 4, 2009, California Plumbing Code adopted new regulations to help provide flexibility with water reuse systems.

California greywater defined

Greywater, defined by the California Health and Safety Code (Section 17922.12a) is “untreated wastewater that has not been contaminated by any toilet discharge, has not been affected by infectious, contaminated, or unhealthy bodily wastes, and does not present a threat from contamination by unhealthful processing, manufacturing, or operating wastes.” The Code continues to specify what systems can provide water to the system, the list includes: bathtubs, showers, bathroom washbasins, clothes washing machines, and laundry tubs. Any wastewater coming from kitchen sinks or dishwashers cannot be classified as greywater. The California Water Code (Section 14877) defines a greywater system as “a system and devices, attached to the plumbing system for the sanitary distribution or use of greywater.” The most commonly approved greywater systems are for irrigation purposes with heavy support for drip systems. However, greywater can also be used indoor if needs require. Cities or countries have the ability to add stricter standards to that of California’s and care must be taken learn about the local standards.

Summary Plumbing Code Ch. 16A

Chapter 16A, "Nonpotable Water Reuse Systems" was added as an emergency greywater regulation to the 2007 California Plumbing Code. The regulations were identifies as "emergency" to eliminate the 18 month waiting period that would otherwise have been required. Chapter 16A was approved by the California Building Standards Commission (CBSC) on July 30, 2009. The emergency regulations were filed with the Secretary of State on August 4, 2009, effective immediately upon filing. The Nonpotable Water Reuse Systems (Chapter 16A) is now part of Title 24, under Part 5 of the 2007 California Plumbing Code and was made a permanent part of the HCD Plumbing Code on January 27, 2010, with the unanimous approval of the CBSC.

The objectives of Chapter 16A are to conserve water by facilitating greywater use, reduce the number of non-compliant greywater systems, grovide guidance, and provide an alternative that would relieve stress on private sewage disposal systems^[2]. Chapter 16A establishes minimum requirements for the installation of greywater systems. Part I of the code covers all persons and occupancies regulated by the Department of Housing and Community Development (HCD). The purpose of the code is to provide guidance to users while adding more flexibility to the process. This chapter of the code contains provisions which allows for the installation of limited types of greywater systems to be installed without a construction permit. However the code does not eliminate the need for persons considering the installation of a greywater system from contacting local authorities to ensure they are informed and in compliance with local requirements or prohibitions.

The Department of Water Resources (DWR) adopted Part II of Chapter 16A, which covers general permitting, labeling, signage, inspection and testing of the recycling water system. The main purpose of Part II of Chapter 16 is to insure the greywater system is identified so the public and persons work on or around the system are informed on the contants of the greywater pipes.

Title 24, Part 5, Chapter 16A "Nonpotable Water Reuse Systems" (Parts I and II)

California design criteria

The citeria set by Chapter 16A are given below, however it is important to check with local enforcment agencies for other local rules and regulations.

All greywater systems must meet the following requirements:

• Not connected to potable water system
• Design is based on location, discharge capacity, soil type and groundwater level
• The area of discharge must be on the same plot as the source, unless lawfully exempt.
• No construction until plan is approved (except for cloths washer or single fixture system)
• Dual discharge must be available to switch between greywater and sewer
• No dipper washing or contact with any fecal material
• Greywater may not

be used for spray irrigation pond up runoff discharge to storm sewer discharge to surface body of water

• The discharge point must be covered by 2 in (51mm) material (mulch, rock, soil)
• The greywater can not be used on root crops or edible parts of food crops

Greywater systems are separated into three categories:

1. Single Fixture or Cloths Washer
   • no permit required
2. Single System
   • exceeds washer or single fixture system
   • capacity is 250 gallons per day or less
   • Construction permit required
3. Complex System
   • multi family or multi dwelling unit
   • capacity is greater than 250 gallons per day
   • Construction permit required

For Construction Permit

• Applies for Small or Complex Systems
• Identify groundwater level and soil type for absorption qualities

- may use a 3 foot vertical test hole to show groundwater is lower than hole

• All components must be water tight
• Must be inspected by enforcement agency

Wetland design

A constructed wetland can be used in greywater applications to reduce pollutants before the water is released for irrigation, groundwater recharge, rivers, or natural wetlands. Greywater may contain, high levels of nutrients, and having a wetland treatment system can reduce contaminates through biological treatment and generate a healthier and more productive ecosystem. Greywater is wastewater generated from showers, baths, sinks and cloths washing machines. Greywater may not come in contact with fecal material due to contamination from pathogens. Because greywater it will contain soaps, cleaning products, food particles and dyes, which may have nitrates, phosphates, bacteria, bleaches, solids (organic and not), and foam causing elements. Using water that contains these things may cause degradation to the surrounding environment, by changing the pH, overloading nutrients, and increases oxygen demand ^[3]

How it Works"' Greywater is discharged from the house to a either directly to into the greywater wetland or to a primary treatment system before going into the wetland. The primary treatment separates out some of the larger solids greses and oils. Primary treatment can be accomplished with filters, grease traps and settling tanks. In the greywater wetland the water undergo secondary treatment through filtration and other biological processes. The biological processes include the plants in the wetland, the bacteria that live on and around the vegetation and from the decomposition of the settled solids.

Primary treatment

Filters

Grease traps

Settling tanks

Subsurface flow wetland

Materials

list of required materials for construction of a subsurface flow wetland.

Sizing

Calculator goes here

Plumbing

Maintenance

Provide some general maintenance checks and timeline or continued operation of a subsurface flow wetland

Resources