Standard Historical Last Updated: Dec 21, 2022 Track Document
ASTM E2635-14

Standard Practice for Water Conservation in Buildings Through In-Situ Water Reclamation

Standard Practice for Water Conservation in Buildings Through In-Situ Water Reclamation E2635-14 ASTM|E2635-14|en-US Standard Practice for Water Conservation in Buildings Through In-Situ Water Reclamation Standard new BOS Vol. 04.12 Committee E60
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Significance and Use

4.1 General—As the world’s population increases, so does the need for water to meet various needs, as well as the need to manage wastewater. Already accepted and endorsed by the public in many urban and agricultural areas, properly implemented nonpotable water reuse projects can help communities meet water demand and supply challenges without any known significant health risks.

4.1.1 Many communities throughout the world are approaching, or have already reached, the limits of their available water supplies; water reuse has become necessary for conserving and extending available water supplies. Where the availability of water limits development, water reuse can facilitate social and economic developmental needs in an environmentally responsible manner.

4.1.2 Many communities are also approaching, or have already reached, the limit of available water treatment facilities. New facilities and infrastructure are costly. In-situ water reuse reduces load on community wastewater facilities.

4.1.3 Additionally, many communities face increased security issues in safeguarding water sources and treatment. In-situ systems provide for redundancies and diversified systems that decrease security issues associated with centralized facilities.

4.2 Sustainable Development—This practice is consistent with the general principles for sustainability relative to building as identified in Guide E2432. It addresses the environmental, economic, and social principles as follows:

4.2.1 Environmental—Water is a natural resource. Sustainable use of natural resources requires that the resource is utilized efficiently and in a manner that preserves or enhances the quality of that resource and does not adversely alter the balance between the renewable resource and the rate of consumption for building-related purposes. Utilization of technologies, such as in-situ water reclamation systems that help conserve water enable more sustainable use of water than standard construction.

4.2.2 Economic: Direct Costs/Benefits—Direct cost/benefits include first costs/benefits as well as operating costs/benefits such as: utility costs, maintenance and repair costs, and costs associated with replacement of component materials and systems. Utilization of technologies, such as in-situ water reclamation systems that help reduce building demand for potable water can reduce utility costs and prevent moratoriums on new construction. Indirect Cost/Benefits—Sustainable building practices seek to identify associated external costs/benefits, minimize associated external costs, and maximize external benefits. Utilization of technologies, such as in-situ water reclamation systems that help reduce the amount of wastewater discharge from a building reduce demands on municipal water infrastructure. This includes costs for centralized treatment and distribution. Significant energy is expended for treatment and distribution of water. For example, in California, an estimated 19 % of electricity, 32 % of natural gas consumption, and 88 billion gallons of diesel fuel annually power the treatment and distribution of water and wastewater.6

Note 1The Final Report includes Table 1–2: Range of Energy Intensities for Water Use Cycle Segments, below:6


Range of Energy
Intensity, kWh/MG

Water-Use Cycle Segments



Water Supply and Conveyance


14 000

Water Treatment


16 000

Water Distribution


1 200

Wastewater Collection and Treatment

1 100

4 600

Wastewater Discharge



Recycled Water Treatment and Distribution


1 200 Social—Sustainable buildings protect and enhance the health, safety, and welfare of building occupants. Utilization of technologies, such as in-situ water reclamation systems that help diversify and decentralize critical health, safety, and welfare infrastructure help promote the safety and security of the general public.

4.3 Continual Improvement—No specific technology is required by this practice. Utilization of performance requirements rather than prescriptive requirements is intended to promote continued research, development, and improvement of as in-situ water reclamation systems.


1.1 In an effort to help meet growing demands being placed on available water supplies and water treatment facilities, many communities throughout the United States and the world are turning to water reclamation and reuse. Water reclamation and reuse offer an effective means of conserving the Earth’s limited high-quality freshwater supplies while helping to meet the ever growing demands for water in residential, commercial, and institutional development. This practice sets forth a practice for water reuse in buildings and related construction, encompassing both graywater and blackwater in-situ reclamation.

1.1.1 This practice specifies parameters for substituting reclaimed water in place of potable water supplies where potable water quality is not required.

1.1.2 This practice specifies limitations for use of reclaimed water in-situ. It is not intended for application to the use of reclaimed water delivered from an offsite municipal wastewater treatment facility.

1.1.3 This practice specifies performance requirements for in-situ reclaimed water systems. It does not specify particular technology(ies) that must be used. A variety of technologies may satisfy the performance requirements.

1.1.4 This practice specifies requirements for water stewardship associated with in-situ water reuse. Consistent with Guide E2432 and for purposes of this practice, water stewardship includes both quantity and quality impacts on water used in buildings.

1.2 Implementation of this practice will require professional judgment. Such judgment should be informed by experience with sustainable development, including environmental, economic, and social issues as appropriate to the building use, type, scale, and location.

1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

1.3.1 Exception—Solely SI units are used in Table 1, Table X3.1, and Table X4.1.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

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Book of Standards Volume: 04.12
Developed by Subcommittee: E60.01
Pages: 11
DOI: 10.1520/E2635-14
ICS Code: 13.060.25