How do I know if my sewage system is not working properly?

Some signs of an improperly operating sewage system and system failure include:

• Toilet is slow to drain or other fixtures do not drain properly or backup.
• Leakage of water is occurring in the leaching bed area.
• There are wet spots, depressions or soggy areas over the leaching bed.
• In the spring or fall or during wet weather one or more of the above problems occur.

 
What causes a sewage system to fail?

Saturation of the leaching bed (tile and trench area remain full of effluent) will eventually lead to sewage system failure. Saturation occurs when the soil surrounding the leaching bed cannot accept the quantity of effluent the leaching bed is discharging. The quantity of effluent from the household may be too great for the design of the leaching bed, surface or ground water may be flooding the leaching bed with water or, the soil has clogged.

Liquid from sources other than the sanitary sewage system may be entering the leaching bed and causing saturation. Sump pumps that drain footing water and enter the household plumbing can easily overload a system. Rainwater downspouts directed toward the leaching bed can saturate the soil and lead to premature failure of the leaching bed. Any or all these factors can lead to saturation and clogging of the soil. Clogging of the soil is associated with the build up of a biological mat (called the biomat) in the leaching bed trenches

In order for the leaching bed to function properly it must drain completely. The leaching bed functions best in the presence of oxygen. Suspended solids discharged form the septic tank are dispersed by the leaching bed over stone in the trenches and into porous fill material in the bed. The suspended solids are held by the stone and soil particles and in the presence of oxygen are readily broken down by aerobic bacteria in the soil and transformed into nutrients and harmless substances that are leached deeply into the soil. If the leaching bed does not drain completely the available oxygen is soon depleted and the aerobic bacteria die off and are replaced by anaerobic bacteria. Anaerobic bacteria will still break down organic matter entering the leaching bed but at a much slower rate and with different results. Consequently an organic biomat eventually builds up and the system fails. Essentially the first few centimetres of the soil (soil interface) become clogged and are unable to pass effluent.

In areas with fissured rock and little soil cover leaching bed clogging can sometimes be missed if channelling occurs. The leaching bed will build up a hydraulic load and will seek the path of least resistance. Sometimes a crack, crevice, void or channel are formed through the leaching bed and soil allowing the effluent to discharge deep into rock fissures rock, rubble, or very porous soil. Under such conditions the sewage will reach the aquifer without proper treatment and contaminate the ground water table. These same conditions can occur if a drainage tile is located too close to the leaching bed area.
 

Salt has also been associated with premature leaching bed failure. This appears to be mainly associated with finely grained soils such as clay. Sodium from the salt through some mechanism not completely understood bonds the soil particles together into an impermeable layer that grows in density over time which ultimately seals the leaching trenches and surrounding soil.