Septic System

Operating Instructions & Guidelines

FOR EMERGENCIES, PLEASE CONTACT:   MWRD – Operations & Maintenance at (615) 893-1223 


It’s important to understand that the first step to a successful sewage treatment and disposal system begins with homeowner education.  A knowledgeable homeowner can prevent premature failures and eliminate costly repairs.  Your effluent collection system is composed of a septic tank, effluent pump, and plastic pressure mains.  All waste from your house flows into the septic tank where it is digested.  The solids settle to the bottom of the tank. The scum floats to the top.  The middle portion of the tank remains fairly clear.  This liquid, commonly referred to as gray water, is pumped out of the tank into the pressure sewer main.

A properly maintained septic tank provides a high degree of treatment and yields an effluent that is relatively free of greases and solids that can clog the effluent filter and pump.  The best practice is not to discharge anything into a septic system that is poisonous or that may inhibit the ability of the bacteria in the tank to break down the solids.  An excellent guideline that should be practiced in every household is not to dispose anything into the septic tank that hasn’t first been ingested, except for toilet paper and mild detergent.


DO call MWRD at 615-893-1223 whenever the alarm comes on (sounds like a smoke alarm). The audible alarm can be silenced by pushing the illuminated light located directly above the “PUSH TO SILENCE” label on the front of the electrical control panel. With normal use, the tank has a reserve storage capacity for 48 hours.Step System

DO familiarize yourself with the location of the electrical control panel and note the number on the panel.

DO coordinate the location of new landscaping or permanent structures with MWRD prior to installation to ensure that the integrity of the septic tank and service lines are not jeopardized.

DO practice water conservation.  By reducing the amount of water going into your system, you can extend the life of the system and reduce the power consumption.  Wash clothes and dishes only when you have a full load.  When possible, avoid several loads in one day.

DO be aware that a simple toilet float can hang up and result in over 2,000 gallons per day of wasted water; normal household usage ranges from 160-260 gallons per day.


DON’T dispose water softener backwash in the tank.  The backwash brine contains high levels of chlorides that can destroy the microorganisms and inhibit the biological digestion that occurs in the tank.  The brine solution also interferes with the solid’s sedimentation that occurs in the tank and may increase the flow through the tank from 25 to 50 percent.

DON’T encumber access to the septic tank with landscaping or fencing.

DON’T connect rain gutters or storm drains or allow surface water to get into your STEP system.  This additional water will overload your system and cause a premature failure.  Your septic system was designed only for domestic water use.

DON’T remove the riser access lid on your tank for any reason. If bolts are lost or damaged, contact MWRD.

DON’T ever enter your tank. Any work on your tank shall be done by MWRD. Gasses in the tank may be fatal.

DON’T use an excessive amount of water.  Repair leaky toilets, faucets, or plumbing fixtures (leaky toilets can result in excess flows at 1 gallon per minute).  Use water saving devices such as low-flow showerheads and low volume flush toilets.

DON’T flush or pour any poisons or dangerous and damaging items into your household plumbing system or wastewater treatment system. This list includes but is not limited to the following: 

• Prescription medications or similar substances

• Combustibles or poisonous products

• Sanitary napkins or tampons

• Diapers

• Condoms

• Rags

• Coffee grounds

• Chlorine bleach, chlorides, or pool/spa products

• Eggshells

• Water softener treatments, backwash, or salts

• Fruit seeds

• Cigarette butts

• Beans

• Flushable/baby wipes

• Chewing gum

• Paper towels

• Trash

• Newspapers

• Cooking grease and meats

• Swiffer Sheets

• Hair

• Pet dander

• Chewing tobacco

• Cleaning products, floor waxes or carpet detergents 

• Excessive amounts of oils, including bath/body oils

• Fertilizers, pesticides/herbicides, or agricultural compounds

DON’T dump recreational vehicle (RV) waste into your septic tank because it will increase the amount of solids entering the tank and the frequency of required septage pumping.   Some RV waste may contain chemicals that are toxic or that may adversely affect the biological activity in your tank.

DON’T use garbage disposal systems to dispose of non-biodegradable materials because they increase the amount of solids entering the septic tank and the frequency of required septage pumping.  Compost scraps or dispose with your trash.

DON’T pour grease down the drain.  Collect grease in a container and dispose of in the trash.  Pouring grease down the drain is the fastest way to ensure a system failure and expensive repair.

DON’T use special additives that claim they will enhance the performance of your tank.   Additives do not improve the performance of the septic  tank and can cause major damage in other areas of the collection system.  The natural microorganisms and bacteria that form in your system are sufficient.   These organisms generate their own enzymes for breaking down solids.


Replace the following hazardous products with ones less environmentally harmful.  The hazardous cleaners are listed in boldface, followed by a suggested substitute.

Ammonia-Based Cleaners:   Sprinkle Baking Soda on a damp sponge.   For windows, use a solution of 2 Tbs. White Vinegar to 1 qt. water.  Place the mixture into the spray bottle.

Disinfectants:  Use Borax: ½ cup in a gallon of water; deodorizes as well.

Drain Decloggers:   Use a plunger or metal snake, or clean trap.

Scouring Cleaners and Powders:   Sprinkle baking soda on a damp sponge or add 4 tbs. baking soda to 1 qt. warm water or use Bon Ami.  These options are inexpensive and will not scratch.

Carpet/Upholstery Cleaners:   Sprinkle on dry cornstarch or baking soda, then vacuum.  For stains, blot with white vinegar in soapy water.

Furniture/Floor Polishes:   To clean, use oil soap and warm water.   Dry with soft cloth.  Polish with 1 part lemon juice to 2 parts oil of any kind, or use natural products with lemon oil or beeswax in mineral oil.

Toilet Cleaners:   Sprinkle on baking soda or Bon Ami, then scrub with toilet brush.

Brass and Copper Cleaner:   Scrub with a used half of lemon dipped in salt.

Stainless Steel Cleaner:   Use scouring pad and soapy water.

Silver Cleaner:  Rub gently with toothpaste and soft wet cloth.

Oven Cleaner:   Quickly sprinkle salt on drips, then scrub.  Use baking soda and scouring pads on older spills.

Laundry Cleaners:   Choose one with zero phosphate content or use soap flakes with 1/3 cup of washing soda.  Wash clothes in pure washing soda to remove detergent residues before switching.