Your vent problem is very easy to correct, however there are a number of serious design problems in your leach bed, which could result in serious fines or jail time.

If you are under the International Residential Code (IRC) the maximum developed length of pipe from the trap weir to the vent opening my not exceed the diameter of the pipe divided by the pitch of the run. In simple terms, if you have a 2" pipe with a ¼" per/ft pitch the maximum distance from the trap weir (the point on the trap where the inverted U section turns horizontal on the output side) to the vent opening may not exceed 2" / .25" = 8.

Under the Uniform Plumbing Code the maximum developed length of a 2" waste arm may not exceed 5.

The vent pipe must rise vertically until it reaches an elevation not less than 6" higher than the flood level rim of the highest fixture served by that vent.

In plumbing any line which rises at an angle of 45degrees or greater above horizontal is considered a vertical pipe, therefore to correct your vent problem you could cut out the horizontal offset and install a riser at 45degress from the waste line to the vertical vent.

Having now corrected your vent problem, let us now examine the leach field.

Quote-"The way we first ended the gray water system was to tee in three place at the end of the run, spaced approximately 10 apart, and put a short vertical drain pipe in each of the three "final drain ports" to distribute the gray water over a larger area."

"When we discovered we were having a drainage problem, we eliminated the three "final drain ports", trenched out to a lower portion of our back yard and just left the end of the 2" ABS drain pipe - at its minimum ¼" per foot slope facing straight out nearly parallel to the ground allowing the water to run down a small hill to remove any backpressure issues that were introduced by the vertical pipes at the end of the gray water drain system in our first design."
Under Federal Law willfully discharging effluent (gray-water or black-water) on a surface watershed is punishable by fines up to $10,000 per day for every day of proven offence and jail terms not to exceed 1yr.

From the specifications set forth by the California Graywater Standards we may use a graywater system to discharge waste water from bathtubs, showers, lavatories, laundry washing machines (no soiled diapers) and laundry sinks.

We may not use a graywater system to discharge waste from a toilet, kitchen sink, dishwasher or a laundry washing machine that is used to wash soiled diapers.

The first step in designing the graywater leachbed is to first determine the volume of flow. Understanding that the number of occupants in a structure may change from day to day we then use a formula based upon the number of bedrooms in the structure thus for computing occupancy we allow 2 persons for the master bedroom and 1 person for each additional bedroom. Example, a 3br house would have an occupancy rating of 2 for the master and 1 for each additional bedroom so the combined occupancy for a 3br is 4 people.

We must then allow 25gal/day for each occupant plus, if the laundry is connected to the graywater system we must allow an additional 15gal/person per day.

Based upon your description let us assume that you only have one shower in the master bedroom connected to your graywater system. The volume would then be 2 occupants x 25gal/person = 50gallons/day.

You could then connect your pipe to a perforated pipe, which has a minimum volume of 50gal, but the total overall length of the perforated pipe may not exceed 100. A 3" pipe has a volume of 2.75gal/ft so a 3" line 137.5 long would contain 50gal, however, the length of the line exceeds the maximum allowable length of 100 so you would have to increase the line to 4" diameter. A 4" line has a capacity of 1.53/gal so you would need 50gal x 1.53ft/gal = 76.5 of 4" perforated pipe.

If you have more than one shower connected to your graywater system you would need to configure for a larger whole house type system. For a larger system you can consult the Calif.Graywater Landscaping Guide Book, which can be downloaded in PDF format at:

http://www.owue.water.ca.gov/docs/graywater_guide_book.pdf

Thank you so much for your swift and wonderfully detailed response. Your knowledge and experience is a great help to us.

First, let me say that our initial gray water system drain setup was just a test to see how it was working before we finalized the system. We had plans to drain into a storage tank system if we exceeded the Tucson, AZ gray water guidelines which are much less stringent than Californias gray water guidelines as a result of AZs restricted supply of fresh water and our states desire to conserve the limited fresh water supply we have. Fortunately, we do not exceed our local gray water guidelines as our gray water is only from one shower and does not run off of our property.

If I understand your statement:

"if you have a 2" pipe with a ¼" per/ft pitch the maximum distance from the trap weir (the point on the trap where the inverted U section turns horizontal on the output side) to the vent opening may not exceed 2" / .25" = 8"

then we are OK as our vent pipe is almost exactly 8 from the trap weir.

Im not sure what this means:

"Under the Uniform Plumbing Code the maximum developed length of a 2" waste arm may not exceed 5."

But since we are under and are within the specifications of - the local Tucson, Pima County, AZ plumbing gray water guidelines it might not matter.

Do you happen to know whether there is a limitation on how far we can run the drain before the actual drain opening into the perforated pipe youve proposed? Right now, our run is about 60 from the drain in the shower to the end of the gray water drain pipe.

Regarding the vent pipe rise: I can replace the 2 flat vent pipe run with a 45 degree bend then take that directly to the 10 vertical vent pipe. Or replace the tee and this time turn the tee up and set the branch off point from the tee to the vent pipe at 45 degrees instead of (almost) parallel to the ground like the existing one is set. Thanks for clarifying this for me.

I believe federal law supersedes state and local law. However, the AZ Department of Environmental Quality clearly spells out the guidelines for using gray water at home in Arizona. I have pasted an excerpt of the guidelines at the end of this posting, along with the web address for the entire brochure.

Thank you also for the estimation of water usage per person per shower:

"2 occupants x 25gal/person = 50gallons/day"

There is nothing else hooked up to this gray water drain system, only this one shower. So 50 gallons/day is about how much water will be going out for gray water irrigation.

And this information you gave us is invaluable:

"You could then connect your pipe to a perforated pipe, which has a minimum volume of 50gal, but the total overall length of the perforated pipe may not exceed 100. A 3" pipe has a volume of 2.75gal/ft so a 3" line 137.5 long would contain 50gal, however, the length of the line exceeds the maximum allowable length of 100 so you would have to increase the line to 4" diameter. A 4" line has a capacity of 1.53/gal so you would need 50gal x 1.53ft/gal = 76.5 of 4" perforated pipe."

This formula will help us calculate what kind of leach field we need based on the length of the run of the perforated portion of the drain pipe. The entire width of our back yard (the part were trying to irrigate) is not much more than 70. Right now, the gray water from a 10 minute shower wont even make it to the end of the temporary test trench I dug from one end of our lower back yard to the other. And the water never even runs off anywhere into the back yard at 102 degree Fahrenheit average daytime / 90 degree Fahrenheit average evening temperature the water doesnt even sit in the trench very long. What doesnt get absorbed into the dirt right away evaporates pretty quickly even in the evening. So I feel confident that were not going to exceed the basic requirements from our local and state laws. The local plants and critters (lizards, ants etc.) are having a great time at our new back yard oasis though!

My wife and I really want to thank you for all your time and for sharing your knowledge and experience. The information you provided will help us set up our gray water system so it is safe, efficient and environmentally sound. Thank you very much again.

Here is the information I mentioned earlier:

http://www.azdeq.gov/environ/water/permits/download/graybro.pdf

The basic requirements to use gray water at your home are simple:
Residents must adhere to the guidelines for a Reclaimed Water Type 1 General Permit. A Type 1 General Permit requires no formal notification to the department, no review or design approval, and no public notice, reporting or renewal.

Although you dont have to apply to receive a formal permit for permission to use gray water, you must abide by the 13 best management practices (BMPs) listed in this brochure, which were developed to protect public health and water quality.

Permit Eligibility and Usage Requirements
The general permit is meant for private residential use only. Gray water must be used on the site where it is generated. The area of use cannot be accessible by the public.

Under this general permit, gray water can only be used for irrigation not for dust control, cooling or other water uses.

Only drip or flood irrigation with gray- water is allowed. Spray irrigation is not permitted due to the potential for inhalation or drifting off-site.

Gray water flow must be less than 400 gallons per day.

In general, no city, town or county may limit the use of gray water if the use is allowed by this general permit (ARS §49-204).

For a copy of the gray water rule, call the nearest ADEQ office or download it at:
www.azsos.gov/public_services/title_18/18-09.pdf.
The gray water rule can be found in Title 18, Chapter 9, Article 7.

Having done a consulting job for new construction in Phoenix, I know for certain that the Phoenix,Az City plumbing code is based upon the Uniform Plumbing Code and I believe that the Ariz. State Plumbing code is also based upon the UPC.

Under the UPC the maximum allowable length of a 2" line from the trap weir to the vent opening is 5'.

Thanks for the clarification. If we swap out the 2" for 3" pipe will we be able to go to 8' from the trap weir to the vent opening?

Or is the maximum distance fron the trap weir to the vent opening 5' regardless of the size of the pipe?

And if we go so far as to swap out the 2" drain pipe should we just go to a 4" pipe to ensure that we solve the "pooling water in the shower floor" problem?

Thanks very much again for all your time and help!