In rural and semi-rural areas where municipal water and sewage lines are unavailable, homeowners must provide their own water and sewage systems.

A safe and effective septic system consists of an underground tank and a leach or drain field that work to cleanse and purify household waste water.

septic system


The average individual uses anywhere from 50 to 350 gallons of water per day for drinking, cooking, washing, flushing the toilet, and other household purposes. Most (99.9%) of sewage is water. The remainder is solid. The solid component is 80% organic and the remaining 20% is inorganic. The organic substances derive from feces, detergents, soaps, urine and food bits produced by garbage grinders. Water softeners, borax, paint, photographic chemicals, household cleaners and the like are sources of the inorganic solids found in household sewer lines.

About 50% of sewage is Gray Water. It is less polluted water, such as the water from the kitchen sink, the shower and the bathtub. The other 50% is Black Water which is water used to flush the toilet.


Currently, permits are required from the local Health Authority before installation of a septic system. It is also common practice for lending institutions to require a septic sewer system inspection prior to loaning funds for the purchase of a new home with a septic system.

Canadian Home Inspection Services performs a comprehensive evaluation of the septic system which focuses on the needs of the home buyer. The inspection begins similarly to that of the Health Authority and also includes a determination of tank capacity, an observation of the inside of the tank,a test on the efficiency and effectiveness of the leaching field and a percolation test of the soil. Further explanation of these tests is provided on the underside.

The diagram to the right shows a typical septic system and its components. Potential and existing problems can occur in any of the main components (dwelling, tank, leaching bed, sewer line). Therefore, it is extremely important to assess the system’s condition and working order prior to the purchase of a new home. A new system can cost approximately $20,000+ which is a high price to pay after the purchase of a new home. An inspection will either help detect a problem that currently exists or give peace of mind.

If you plan to upgrade and add square footage to your home, you will need to know what the existing system was initially designed for and what upgrades you will need to do to allow for your new bathroom or living area upgrade.

If your existing dwelling is serviced by a private septic system, the Ontario Building Code requires that the performance level (the ability of the septic system to function properly) of the existing septic system cannot be reduced or degraded. It further states that the performance level may be reduced or degraded where proposed construction will:

a) Increase the number of bedrooms in the existing house, or

b) Exceed 15% of the existing finished area of the existing house, or

c) Add new plumbing fixtures to the existing house.

In order to determine possible performance level changes resulting from your plans, you will need to complete a “Septic Change of Use” permit application and to submit it with your building permit application.

During the review process, your municipal Planning and Development Official will look at the existing septic system design and the proposed changes to confirm that the performance level of the septic system will not be degraded as a result of these changes. Even though you as the current resident may not have additional people in your house, the use of the space may change should you decide to sell your house, and this must be taken into consideration during the review process.


Sizing the Tank — determining the capacity of the tank will ensure that the tank will accommodate for all residents of the household. This step is particularly important for larger households.

Leaching Field — the effluent from the septic tank is carried into the leach field through perforated plastic pipe or short lengths of loosely-joined clay pipe.

The liquid flows out of the pipe and through the coarse gravel in which the pipe is bedded. The location and adequate functioning of the field is extremely important for the effluent treatment and evaporation process.

PercolationTest — determines the rate at which the soil in the drain field can absorb water. The ideal drain field is light, airy, porous and dry. Percolation is so important that some property sales contracts require good percolation rates.