This is the state law:
§ 73.62. Standards for holding tanks.
(a) A holding tank shall be constructed to meet the specifications of § 73.31(b)(1) (relating to standards for septic tanks).
(b) The minimum capacity of a holding tank is 1,000 gallons or a volume equal to the quantity of waste generated in 3 days, whichever is larger.
(c) The holding tank shall be equipped with a warning device to indicate when the tank is filled to within 75% of its capacity. The warning device shall create an audible and visual signal at a location frequented by the homeowner or responsible individual.
(d) Disposal of waste from a holding tank shall be at a site approved by the Department.
I have a 1,000 gallon holding tank for my "gray water". My property is small and is very close to a small stream. The SEO
advised that the holding tank needed to be at least 50 ft from the stream when I installed it about 8 years ago. I have it pumped out every 1 or 2 years. However, I only visit my camp for short periods of time 4 or 5 times a year. You really need to conserve water when showering, flushing and washing dishes. I came from a camp with no running water and only an outhouse. So I don't mind the inconvenience to have a hot shower and a flush toilet inside of the building. We still have our old outhouse and use it quite often. Some townships and counties have different restrictions, so be sure to check with the SEO
as has been said before. By the way, the cost to pump out the tank is somewhere between $250 and $300.