Section 15.262 - Greywater Systems(1) Greywater from residential, commercial and public facilities may be discharged or reused in accordance with the provisions of 310 CMR 15.262. For purposes of 310 CMR 15.262, public facilities shall include facilities owned or operated by a local political subdivision of the Commonwealth or an agency of the Commonwealth or federal government.(2)Soil Absorption System for Greywater. When the total discharge to an on-site subsurface sewage disposal consists entirely of greywater as defined in 310 CMR 15.002 (Greywater), the following shall apply:(a) the minimum soil absorption area for residential systems, as determined by the results of the site evaluation set forth in 310 CMR 15.100 through 15.107 and in accordance with the appropriate long-term acceptance rate criteria specified in 310 CMR 15.242, for design of a soil absorption system for new construction of a facility, or for upgrades to existing systems may be reduced by no more than 50%, provided, however, that for new construction, the owners of residential facilities shall demonstrate that a system in full compliance with 310 CMR 15.000 can be installed on the facility to serve the proposed design flow. Reductions for commercial and public facility systems shall be determined on a case-by-case basis as approved by the Department in accordance with 310 CMR 15.203(6).(b) the depth of soil placed as backfill over the system shall be at least nine inches, placed in lifts and sufficiently compacted to prevent depression due to settling which may intercept surface runoff above the system. Backfill must be clean and free of stones greater than two inches in size. Tailings, clay, or similar material is prohibited.(c) in a remedial upgrade of an existing system with no increase in flow, the required separation between the bottom of the soil absorption system and the high groundwater elevation may be reduced to a minimum of two feet in soils with a recorded percolation rate of more than two minutes per inch or a minimum of three feet in soils with a recorded percolation rate of two minutes or less per inch.(3)Septic Tanks or Filter for a Greywater System. Greywater systems may include either a septic tank or a filter, provided the filter has been approved by the Board of State Examiners of Plumbers and Gas Fitters and/or the Department in accordance with 310 CMR 15.289(1)(b). (a) The septic tank shall have a minimum effective liquid capacity of 1000 gallons and shall be designed in accordance with 310 CMR 15.223 through 15.226.(b) Septic tanks for commercial and public facilities shall be at least b the size of a septic tank based on the design flows presented in 310 CMR 15.203.(c) When 310 CMR 15.203 does not provide design flows the design flow shall be based on historical flows (one year or more) of the facility or similar facilities if historical flows are not available and shall be 200% of average water meter readings or 125% of the recorded peak flow, whichever is greater.(4) Greywater may be discharged using an alternative to a soil absorption system approved by the Department pursuant to 310 CMR 15.280 through 15.288.(5) Greywater from commercial or public facilities may be approved by the Department on a case-by-case basis for reuse in accordance with 314 CMR 20.00: Reclaimed Water Permit Program and Standards, and applicable policies and guidance of the Department pertaining to wastewater reuse.(6) Greywater systems shall be operated, maintained, and inspected in accordance with 310 CMR 15.300.(7) For residential facilities utilizing composting toilets and greywater systems in nitrogen sensitive areas an allowable loading rate of 660 gpd/acre may be used provided that there is no discharge of blackwater at the facility and the compost is disposed off-site. Annual inspections shall be conducted in accordance with 310 CMR 15.300(5).(8) For commercial and public facilities utilizing composting toilets and greywater systems in nitrogen sensitive areas, an allowable loading rate up to 770 gpd/acre shall be determined by the Department on a case-by-case basis provided that there is no discharge of blackwater at the facility and the compost is disposed off-site. Annual inspections shall be conducted in accordance with 310 CMR 15.300(5).(9) Greywater systems for new construction or increases in flows to existing systems within nitrogen sensitive areas as defined in 310 CMR 15.214 must comply with the nitrogen loading limitations in accordance with 310 CMR 15.215.Amended by Mass Register Issue 1499, eff. 7/7/2023.