Community Development

 HOME OWNER'S MANUAL Septic Systems 101

 


WASTEWATER DEPARTMENT FREQUENTLY ASKED QUESTIONS

What is a septic system?

What is a septic tank?

What happens to the solid materials in the tank?

Why should I maintain my septic system?

How often should a tank be pumped?

How can I locate my septic tank?

What is involved in pumping a septic tank?

Who pumps septic tanks?

Do septic tank additives help?

What is a drain field?

What is a cesspool?

What can I put down my drains into the septic tank?

How close can my septic tank be to...?

How do I find out what kind of sewage system my lot will need?

Who can design my on-site sewage treatment system?

WHAT IS A SEPTIC SYSTEM?

The septic system is a two-part sewage treatment and disposal system buried in the ground. It is composed of a septic tank and a soil drain field. The sewage flows by gravity into the septic tank where the solids settle out of the liquid.  The liquid, called effluent, then flows to the drain field where it soaks into the ground and oxygen breathing bacteria consume and/or kill the remaining sewage, bacteria and viruses so that the water is clean and ready to re-enter the fresh water supply. 

typical septic system

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WHAT IS A SEPTIC TANK?

The conventional septic tank is usually a concrete, fiberglass or plastic watertight structure where the wastewater from toilets, bathtubs, showers, laundry and kitchen collects. It is designed to hold the wastewater long enough to for most of the heavy suspended materials such as fecal matter, soil, grit, and food residues to sink to the bottom of the tank to form sludge. At the same time, lighter materials such as grease, fats and paper products float to the top of the tank where they remain trapped between the inlet and outlet pipes. The water portion or effluent is pushed out of the tank. The effluent, containing organic matter and high numbers of bacteria and viruses, is discharged into the underground piping network called drain field or leach field.

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WHAT HAPPENS TO THE SOLID MATERIALS IN THE TANK?

Solid materials will, over a period of time, settle to the bottom of tank or float to the top. Bacteria that live in the absence of oxygen break down a small part of the solid material and the remainder is removed from the tank by pumping the tank.  Some organic materials decompose very slowly and others such as plastics, metals and other inorganic materials do not decompose at all.

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WHY SHOULD I MAINTAIN MY SEPTIC SYSTEM?

The wastewater drain field will last longer if a regular maintenance schedule is followed rather than waiting for signs of failure to develop. Once signs of failure occur, expensive repairs may be needed. The main obstacle to effective septic tank maintenance is its "out of sight, out of mind" characteristic. There are few tell-tale signs that something is wrong until a major sign appears such as surfacing sewage or back- up’s into the home. If sludge and scum are not removed from the tank they build up resulting in sewage particles being washed out into the drain field where they prematurely clog the soil.  This is the main reason for system failure and usually requires a new system to be installed. Maintenance Tips for a Healthier Septic System:

  • Have the tank pumped every 3 to 5 years, depending on use.
  • Minimize excess water use.
  • Fix leaking faucets and running toilets.
  • Avoid the use of septic system additives.
  • Minimize the use of a garbage disposal.  We recommend that homeowners compost or throw food wastes in the garbage.
  • Avoid planting trees around the system.  Take extra caution when planting near the absorption field inlet pipe.
  • Avoid flushing objects and substances down the toilet that do not easily decompose.
  • Avoid vehicular traffic and construction activities on and around the absorption field area before and after the field system is installed.
  • Divert run-off water from downspouts from your roof, basement and lawn.  They must drain away from the absorption field.

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HOW OFTEN SHOULD A SEPTIC TANK BE PUMPED?

How often depends on the size of the tank and how many people are living in the household. It depends on the overall daily flow and the solids that go into the system. A rule of thumb is that a home with 3 occupants and a 1000 gallon tank should be pumped every 4 years; with more occupants and bigger tanks this number will change.  Some systems may not need maintenance for several years while others may need it every two (2) years, due partly to the particular habits of individual households and the number of people in the family.  It is important to regularly pump a septic system. Please see pumping chart for recommended time frame for pumping your tank.  The volume of scum and sludge accumulated in the tank is another guide for when to pump your tank.  These guidelines are:

            Scum + Sludge > 25-33% of tank volume below outlet level, or

            Scum > 3” &/or Sludge > 12”.

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HOW CAN I LOCATE MY SEPTIC TANK?

If you are not sure where your septic tank system is located, contact the Gila County Wastewater Department to see if there is a record of your septic system. To expedite the file search please provide your Assessor Parcel Number, the 911 address and/or the name of the owner of the property. Your yard may contain clues to the location of your septic system such as pipes sticking out of the ground - a two-way cleanout on the side of the house where the septic tank is located, a black diverter valve after the septic tank, white inspection pipes at the end of each leach line or indentations in the ground where excavation took place. You can also probe the yard to see if you can physically locate the tank. Contractors who are qualified to locate your system can be found in the Gila County Contractors List – Transfer of Ownership Inspectors.  

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WHAT IS INVOLVED IN PUMPING A SEPTIC TANK?

Pumping a septic tank involves exposing the lid of the tank so that both manholes can be opened.  Once the tank is uncovered and opened the scum, sludge and liquid in the tank is completely cleaned out and hauled off by the pumper truck (this cannot be accomplished through a 4 or 6 inch pipe). The liquid/solid mixture, called septage, must be disposed of at an approved disposal site, usually a sewage treatment plant.  Ask your pump truck operator where they will dispose of your septage.

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WHO PUMPS SEPTIC TANKS?

Septic Tank Pumpers are listed in the telephone book yellow pages under "Septic Tanks & Systems- Cleaning".

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DO SEPTIC TANK ADDITIVES HELP?

Yeast, bacteria, enzymes and chemicals are sold with a claim of helping septic systems work better.  However, there is no scientific evidence that additives are effective.  In fact, some cleaners allow the solids in an overloaded tank to be re-suspended in the effluent and transported into the leach lines causing clogging and premature failure.

Additives are not an alternative to proper maintenance and do not eliminate the need for regular pumping of a septic tank. Therefore routine pumping of the tank is a necessity to keep your system in proper operating condition and to avoid premature failure of your system. Addition of chemicals or additives is not recommended and some will actually damage your drain (leach) field.

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WHAT IS A DRAIN FIELD?

The drain field (leach field, disposal trench or subsurface disposal field) distributes the effluent from the septic tank over a large soil area allowing it to percolate through the soil. The soil acts as a filter and disinfectant by removing most of the pollutants and disease causing viruses and bacteria found in the effluent.

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WHAT IS A CESSPOOL?

A cesspool is an excavation or non-watertight unit that receives untreated, water-carried, liquid human waste from a home or business allowing direct discharge into the soil.  The use of cesspools in Arizona has been prohibited since 1976.  More information regarding properties where sewage disposal is by cesspool can be found in these documents: Water Quality and Your Property Value, Gila County Cesspool Policy.

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WHAT CAN I PUT DOWN MY DRAINS INTO THE SEPTIC TANK?

Be Careful About What Goes Down the Drain!  Make your septic system last a long time.  Replacing it will cost $3,000 to $12,000, that is if your land still qualifies for a conventional septic system, and up to $30,000 if it requires an alternative system because of the characteristics of the soil and lot.  Homeowners must be aware that what is disposed of within their household plumbing system eventually ends up in their septic system, and eventually into the groundwater.  Unusually large water usage from inefficient water fixtures and very large amounts of laundry can cause hydraulic overload of the absorption field.  This can result in surface ponding and damage to the system.  Chemicals such as: paint thinner, automotive oil or bleach that are poured into the household drains disrupt biological activity in the tank, contaminate your ground water, and clog the soil pores in the absorption field.

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HOW CLOSE CAN MY SEPTIC SYSTEM BE TO...?

The most frequently requested setbacks from any part of your on-site wastewater system are:

            Building footings and foundations - 10’

            Driveways and parking areas – 5’

            Home water lines – 5’

            Water mains – 10’

            Wells – 100’

Here is a complete list of Wastewater Setbacks.

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HOW DO I FIND OUT WHAT KIND OF SEWAGE SYSTEM MY LOT WILL NEED?

Having a Soil Test conducted on your lot in the area where the leach field will be installed is the first step toward knowing what type of system your lot will accept to process the sewage generated by your home or business.  Soil Tests are conducted by private contractors who have received training on soil testing, sewage treatment system design and the Arizona On-site rules that govern soil testing, sewage system design and installation.  According to Gila County Ordinance #01-2 the soil test must be observed by a Gila County employee.  In addition to the fees charged by the private contractor there is a fee of $150 payable to Gila County.  The Gila County Contractor’s List – Soil Evaluators Section is a list private parties who may conduct soil tests in Gila County.  The selected party will schedule the soil test with Gila County.

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WHO CAN DESIGN MY ON-SITE SEWAGE TREATMENT SYSTEM?

According to Gila County Ordinance #01-2 septic systems may be designed by private contractors who have received training on soil testing, sewage treatment system design and the Arizona On-site rules that govern soil testing, sewage system design and installation.  A septic system can be designed by any private party listed in the Gila County Contractor’s List – Designers Section.  Ordinance #01-2 further requires that all alternative systems be designed by  Arizona Registered Professional Engineers who are denoted by an * before their name in the same Designer Section of the Contractors List and installed by properly licensed Arizona Contractors listed in the Contractors Section of the Contractors List. 

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