In rural areas, the septic tank system is the most inexpensive and efficient method to dispose of household sewage. A septic tank system that is correctly designed, located, constructed and well maintained will function effectively and safely for years. An improperly designed, located, constructed or inadequately maintained system can seriously endanger health and the environment, and can lead to considerable nuisance and expense.

This Factsheet addresses the care and maintenance of existing septic tank systems. For the construction, alteration, or enlargement of a private sewage disposal system a Certificate of Approval for a sewage system is necessary before any related building construction may begin. In most cases applications for Certificates of Approval, should be directed to the local health unit which acts on behalf of the Ministry of Environment.

Fundamentals of a Septic Tank System

A septic tank system consists of a septic tank and a leaching bed. In Ontario this system is commonly referred to as a Class 4 Sewage System. The septic tank is typically a two chamber concrete (or other approved material) 3,600 - 4,500 litre airtight tank. The leaching bed is comprised of rows of perforated 3 in pipe set 1.6 metres apart on a 6 in stone layer. The bottom of the trenches must be at least 0.5 metres above the groundwater table and 3 ft above bedrock or impermeable soil.

Figure 1. Typical Lay-out of Septic Tank Tile Bed System	Figure 2. Cross-section of the Actual Septic Tank

The septic tank and leaching bed work together to dispose of household sewage. Household sewage includes human body waste, toilet or other bathroom waste, waste from showers and baths, liquid or water-borne kitchen waste or laundry waste.

As household waste enters the larger first chamber of the septic tank the solid portion of the waste settles to the bottom of the tank, while fats and grease rise to the top to form a scum. The settled solid portions are prevented from entering and plugging the leaching bed. Treatment of the settled solids then takes place by anaerobic (without air) bacterial action.

The leaching bed receives the relatively clear but highly polluted liquid portion of the sewage from the septic tank. The sewage is then treated by aerobic (with air) bacterial action as it filters downward through the soil from the leaching bed distribution pipes.

Distances from a Septic Tank System

In locating a septic tank system, the following are minimum horizontal distances that are required under Provincial Regulations. As these distances are minimums, they may have to be increased to prevent pollution if soil or other site conditions so dictate or if a raised leaching bed is used.

No septic tank shall be closer than:

• 15 metres (50 ft) to a well, lake, river, stream, watercourse, pond, spring, or reservoir;
• 1.5 metres (5 ft) to any building or structure (including a swimming pool);
• 3 metres (10 ft) to any property boundary.

No distribution pipe in a leaching bed shall be closer than:

• 15 metres (50 ft) to a well which has a watertight casing to at least 6 metres (20 ft) below ground;
• 30 metres (100 ft) to a spring used as a source of potable water or a well that does not have a watertight casing to 6 metres (20 ft) below ground;
• 5 metres (16 ft) to any building or structure;
• 3 metres (10 ft) to any property boundary;
• 15 metres (50 ft) to a lake, river, pond, stream, reservoir or spring not used as a source of potable water.

Preventative Care and Maintenance

Water Use

Minimize the amount of water used in the household. Excessive use of water could flush solids from the septic tank to the leaching bed which would lead to clogging or plugging of the leaching bed pipes.

Each person in Ontario uses about 300 litres (66 gal) of water a day, the majority of which is used in washrooms by toilets, sinks, showers and baths. Approximately 45% is used for toilet flushing, 30% for bathing, 20% for dish washing and laundry, and 5% for cooking.

Water usage in the home should be kept to a minimum to avoid exceeding the capacity of the septic tank system. If automatic washers and dishwashers are used, make sure full loads are washed each time and stagger their use to reduce peak flows. Retrofitting existing toilets to use less water will also ease the stress on the septic tank and the water supply systems.

Direct all surface waters, pumps, and roof drains away from the leaching bed. This includes the lawn sprinkler.

Chemical Contamination

Moderate use of household drain solvents, cleaners, disinfectants, etc., should not interfere with the operation of the septic tank system; however, indiscriminate use may cause problems.

Do not discharge water softener waste water into the septic tank, unless the system was designed for the extra capacity. Not only does the extra water decrease the capacity of your system, the added salts may lead to a failure of the leaching bed. Water softener waste water should be directed to a leaching pit.

The use of garbage grinders is discouraged as sludge accumulation in the septic tank can be increased by up to 40%. The tank will then have to be pumped annually.

Do not dispose of fuels, grease, paints, thinners, weed or insect killers, cigarette butts, condoms, paper towels, diapers, sanitary napkins, etc., into the septic tank system. A septic tank system can only handle bio-degradable items.

There should be no need to use commercial "starters," "bacterial feeds," or "cleaners." Bacteria in a septic tank system occurs naturally.

Leaching Bed

The area over a leaching bed should have a good grass cover, but should not be planted with trees or shrubs. Tree and shrub roots will seek out nutrient-rich leaching bed tiles and eventually plug them. It is important not to add excessive amounts of solid (more than 0.3 metres) to the top of the leaching bed, as this may prevent evapo-transpiration and reduce oxygen transfer to the bed.

Structures such as patios, pools, sundecks and toolsheds must not be erected over or near the leaching bed.

Keep all vehicles including snowmobiles off the leaching bed. Any compaction of the soil reduces leaching bed performance. Crushed leaching bed pipes can cause backups into your home.

Good ventilation and adequate sunlight should be maintained in the area of the leaching bed.

Repair Maintenance

The septic tank should be inspected at least once every two years and the tank pumped out by a licensed contractor every three or four years. Check the local telephone book yellow pages under "Septic Tanks" for a licensed contractor near you. Regular pumping of the septic tank is the best preventative maintenance you can do and well worth the investment.

Warning: Under no circumstances should a home owner enter a septic tank. Noxious gases which are heavier than air remain in the tank after the top is removed and have caused death both to the original victim and to those who attempt to rescue him/her from the tank.

A septic tank will require pumping if the bottom of the floating scum mat is within 7.6 centimetres (3 in) of the bottom of the outlet fitting or if the surface of the bottom sludge accumulation is within 46 centimetres (18 in) of the inlet fitting. Inspection of scum and sludge layers is not a pleasant task--a septic tank servicing firm can inspect for you.

Septic tank maintenance records should be kept to help you ensure that regular maintenance is carried out.

Trouble Signs

The following is a list of possible trouble signs that indicate septic tank system failures:

• Leaching bed ground is frequently wet and spongy;
• Extra plant growth over the leaching bed area;
• Odours coming from leaching bed area;
• Pooling or bubbling of waste water noticeable on the leaching bed surface;
• Well water containing nitrates or fecal coliform bacteria,
• Slow drains in the house.

In the interest of health and the protection of the environment, any malfunction of a septic tank system must be promptly reported to the local health unit or Ministry of Environment office.