Benoit Septic Homeowner’s Guide

Not sure if your tank needs to be serviced?

Septic tank servicing frequency depends on tank size and number of household occupants. The following chart gives a rough estimate of how often your septic tank should be pumped:

  • Tank Size (gallons)
  • 500
  • 1000
  • 1500
  • 2000
  • 1 Occupant
  • 5.8 years
  • 12.4 years
  • 18.9 years
  • 25.4 years
  • 2 Occupants
  • 2.6 years
  • 5.9 years
  • 9.1 years
  • 12.4 years
  • 3 Occupants
  • 1.5 years
  • 3.7 years
  • 5.9 years
  • 8.1 years
  • 4 Occupants
  • 1.0 years
  • 2.6 years
  • 4.2 years
  • 5.9 years
  • 5 Occupants
  • 0.7 years
  • 2.0 years
  • 3.3 years
  • 4.5 years

Signs that may indicate your septic tank needs to be pumped:

Look for the following signs:

  • Septic odours in the house.
  • Difficulty flushing toilets or draining water.
  • Toilets or drains backing up into the house.
  • Gurgling sounds when flushing.
  • Lush grass growing over your septic field; this means septic effluent is percolating up, and not down as it should.
  • Soggy ground around the septic tank or absorption area.
  • Surface flooding of sewage.
  • High levels of nitrates, bacteria or other contaminants in well water.

How does a septic tank work?

Waste from house plumbing (sinks, showers, toilets, laundry) flows through drain pipes into a two-part system:

  1. A septic tank, whose job is to retain solid waste and begin the process of breaking down contaminants. This process occurs without oxygen, so the tank needs to be sealed.
  2. A soil absorption system, whose job is to permit liquid from the tank to seep into the soil. This consists of underground perforated pipes which evenly distribute liquid into the soil. Naturally-occurring bacteria digest impurities such as suspended solids, organic chemicals, viruses, and bacteria. The resulting purified liquid is then safely absorbed by surrounding groundwater. There is some bacterial action in the tank, but the most important action occurs in the absorption field.

Why does it need to be pumped?

The job of the septic tank is to keep solids from flowing out into the soil absorption system. Floating wastes (such as grease) collect in the scum layer and heavier solid waste settles to the bottom of the tank forming the sludge layer. Separators known as tees (or baffles) permit only liquid to flow out of the tank to the soil absorption system. Should these layers accumulate, solids will flow out and clog the soil absorption system.

If you wait until there are odours, slow drains, sewage backups, or sewage coming up in the yard, it’s probably too late to avoid costly repairs to the soil absorption system.

You can avoid these repairs by having the tank serviced regularly.

Septic tank additives or rejuvenators are not needed in your septic tank.

Some additives such as yeast or harsh chemicals can actually damage the septic system. Yeast can cause frothing and excessive activity in the septic tank, preventing normal settling of solids and coagulation of greases. This agitation forces solid waste into the drainfield and by clogging  the soil, shortens its life. Other septic chemicals can contaminate the environment.

In general, septic system chemicals are not needed and are not recommended. Chemicals and other additives promoted to keep a septic system “healthy” or “free-flowing” or “nourished” are not required nor recommended by experts.

The best way to extend the life of your septic system is to pump and service it regularly.

Tips on maintaining your septic system:

The following 13-point list will help you achieve a long-lasting and healthy septic system;

  1. Reduce water use. Too much water will overload a septic system.
  2. Pump the tank regularly to keep the soil absorption system clear of solids.
  3. Try not to dispose of garbage down the drain. These solids are not digested very well (if at all) by the septic system.
  4. Never cover the ground above the absorption system; this includes pavement, patio stones, sheds, or concrete. The bacterial action required to neutralize septic liquid requires oxygen and this will limit oxygen from getting into the soil.
  5. Do not allow any traffic over the absorption area. This can crush pipes or compact the soil in the summer and reduce the natural insulation provided by snow cover in the winter.
  6. Install a lint filter on your washing machine to keep lint out of your septic system.
  7. Use phosphate-free liquid detergents.
  8. Do not plant trees or shrubs in the absorption area. Roots can clog the perforated pipes and shade the absorption area thereby limiting evaporation.
  9. Keep a good cover of grass over the absorption area to help with evaporation.
  10. Do not water grass in the absorption area. Extra water in the soil will reduce its ability to absorb septic liquid.
  11. Install risers to allow access to the tank without digging.
  12. Keep septic tank lids closed! The tank contains gases that can kill you. There is no oxygen in the tank and bacterial action works best without it.
  13. Some liquids can kill bacteria in the septic tank and thus interfere with normal digestion of solids to liquid. Even if a particular substance does not damage bacterial action, dumping it down your drain can damage the environment or contaminate well water.

What can be flushed into the septic tank in moderation:

  • Ammonia: in normal dilute quantities such as from mopping a kitchen floor.
  • Bleach: if you’re doing a lot of washing using bleach, consider using an oxygen bleach product (sodium percarbonate) as an alternative. Large quantities can damage the septic system.
  • Espom salts: such as used to bathe feet, at normal use.
  • Household cleaners: detergents, fabric softeners, shampoos, and bath soap, at normal levels of household use.
  • Liquor: a bottle or two of unwanted liquor is ok.

What should NEVER be flushed into the septic tank:

  • Toilet bowl cleaners, drain cleaners.
  • Fats, oils, grease.
  • Gasoline, antifreeze.
  • Photographic solutions.
  • Cat box litter.
  • Coffee grounds.
  • Cigarette butts.
  • Furniture polish.
  • Oils such as used motor oil, or unwanted cooking oil.
  • Paints of any kind, latex, oil, alkyd, acrylic, water based.
  • Pesticides.
  • Putty.
  • Paint thinners.
  • Varnishes.
  • Antibiotics.
  • Hydrochloric acid (HCl).