Septic System Installation

NSF Standard 40:
Title: “Residential Wastewater Treatment Systems”
“1.1 Purpose The purpose of this Standard is to establish minimum materials, design and
construction, and performance requirements for residential wastewater treatment
systems.”
“1.2 Scope This standard contains minimum requirements for residential wastewater
treatment systems having simple, defined discharge points and rated treatment capacities
between 1514 L/day (400 gal/day) and 5678 L/day (1500 gal/day).”
“3.6 residential wastewater (wastewater): Human body waste and liquid waste
generated by the occupants of an individual residence.”
“3.7 residential wastewater treatment system: An organized and coordinated system of
components that functions to treat wastewater generated by individual residences.”

30TAC285:
Since the promulgation of these rules in 1997, 30TAC285.91, Table III has stated,
“Commercial/institutional facilities must pretreat their wastewater to 140 BOD5.”
TOWA High Strength Workshop:
“Home plant ATU’s are not designed for high strength, and should not be used for high
strength wastewater.”
“Wastewater is considered high strength if it possesses anything outside the parameters of
residential strength wastewater”, which is considered to be:
BOD < 300 (many say 200) mg/l FOG < no visible film
± 7.4
TSS < 300 (many say 200) mg/l pH

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