Building Inspection Division Hand Outs
Guidelines for Graywater Systems,
Residential Laundry Washing Machine Drains, and
Surface Irrigation
THESE GUIDELINES PERTAIN ONLY TO GRAYWATER SYSTEMS FOR RESIDENTIAL LAUNDRY WASHING MACHINE DRAINS FOR SURFACE IRRIGATION. ONLY THE WASTEWATER FROM RESIDENTIAL LAUNDRY WASHING MACHINES SHALL BE UTILIZED FOR T HE GRAYWATER SYSTEM. ALL OTHER WASTE MUST DRAIN TO THE PUBLIC SEWER IN ACCORDANCE WITH THE CITY OF ABILENE PLUMBING CODE.
INSTALLATION
- Piping installed inside or within a structure shall comply with this guideline and with the International Residential Code, as adopted by the City of Abilene.
- All piping shall be installed by a licensed, bonded plumbing contractor, or a homeowner at his/her homestead.
- A permit shall be obtained from the Building Inspection Department.
- An inspection shall be made before any piping work can be covered up.
- Piping outside the structure shall be installed in accordance with the TNRCC, On Site Sewage Facilities Rules and the City of Abilene Health Department.
- A Certified OSSF Installer or a homeowner of a single-family residence shall install all piping outside the structure.
GRAYWATER DISPOSAL
Disposal shall comply with TNRCC Guidelines as follows:
Graywater from residential laundry washing machines may be discharged directly onto the ground surface under the following conditions:
- Irrigation must not create a public health nuisance such as surface ponding.
- The irrigated area must support plant growth such as bushes or be overlaid with vegetative cover. The area must be of a limited access and use by residents, pets, and to foot traffic.
- Graywater from soiled diapers must be treated in accordance with 30 TAC 285.32 (relating to Criteria for Sewage Treatment Systems), 30 TAC 285.33 ( relating to disposal processes-non-standard for surface irrigation systems), and disinfected in accordance with 30 TAC 285.7 ( relating to Additional Requirements for Surface Irrigation Systems ) prior to irrigation
- Do not irrigate an area if the soil is already wet.
- The use of detergents, which contain a significant amount of phosphorus, sodium, or boron, should be avoided.
- A lint trap at the end of the discharge line is required.
- Residences or commercial laundry operations utilizing permanently installed surface irrigation systems shall adhere to all 30 TAC 285 requirements for surface irrigation.
SPECIFIC REQUIREMENTS FOR PIPING INSTALLATION INSIDE AND ON THE STRUCTURE
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TRAP AND STANDPIPE Each standpipe shall be trapped, and the trap shall be a minimum 2" Each standpipe shall be installed a minimum of 18" and a maximum of 42" above the trap. The trap must be installed above the floor |
DRAIN
Horizontal drain must have a minimum slope of ΒΌ" per foot of fall. PVC and ABS must be supported every 4', Cast Iron must be supported every 5'(may be extended to 10' where 10' lengths are installed.), Copper must be supported every 12' horizontal & 10' vertical. Piping shall be installed to be protected from physical damage. The maximum distance of the fixture drain (the horizontal piping from the vertical drain stack to the p trap, see illustration) shall be 6', measured from the weir of the trap to the vent opening. |
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VENT Each standpipe trap shall have a vent. Each vent shall vent to the outside and be installed by one of the following methods: Vent to the outside independently, and extend a minimum of 6" above the roof terminating in an approved flashing. Revent to an existing sanitary vent. A vent that is to be revented must extend a minimum of 6" above the height of the standpipe before the vent can be offset horizontally, and must be connected to the existing vent with a proper fitting such as a solvent cemented tee for PVC and ABS, soldered tee for copper, and a tee installed with no-hub clamps for cast iron. Or an approved transition fitting listed and approved for the use. The existing vent must terminate outside the structure. An approved Air Admittance Valve conforming to ASSE 1051, and installed a minimum of 4" above the horizontal branch drain or fixture drain being vented, and in a ventilated area. The Air Admittance Valve shall be installed in accordance with the manufacturers installation instructions which are supplied with each valve. |
REROUTING OF THE EXISTING DRAIN
If the existing drain is to be rerouted to the graywater system, provisions must be made to permanently cap the existing abandoned drain line with an approved method:
- PVC and ABS lines shall be capped by solvent cementing a permanent cap on the drain line.
- Copper drain lines shall be capped by soldering a permanent cap on the drain line.
- Cast iron shall be capped by installing a clean-out plug or a cast iron blind plug on the end of the drain.
- Different material may be used to cap the line if a proper transition fitting is used. The manufacturers instructions will show which material may be joined by the use of these fitting.
INDEPENDENT GRAYWATER PIPING SYSTEM
If the graywater system is installed independently of the existing laundry washing machine drain line; measures must be taken to ensure that sewer gas will not enter the structure through the abandoned drain system by capping or plugging the drain line or installing a trap primer to the existing standpipe.
