Ontario Rural Wastewater Treatment
Ontario Rural Wastewater Centre – provides education for individuals who install and
maintain wastewater treatment systems --- these systems are called on-site systems
(septic systems is a specific type of on-site system)
There are approximately 1.2 million on-site systems in Ontario
5 classes of systems of which four of them are:
Class 1 – privies (outhouses)
leaching pits
Class 4 – septic tank/leaching bed
Class 5 – holding tanks (there are concerns regarding this system regarding how the
tank is emptied because of the cost associated with pumping)
On-site systems are used in rural homes and cottages, some small towns and hamlets,
rural businesses and campgrounds --- wherever municipal sewer systems are not
available
Regulations for On-Site Systems
OBC – Ontario Building Code, regulates systems that have a daily flow <10000L/day
MOE – Ministry of the Environment, regulates systems that have a daily flow
>10000L/day
OBC – dictates the location of on-site systems so there is no contamination to water
(e.g. wells, water ways) --- helps to ensure public health, it also regulates the materials
that the systems are made of, as well as the size that is required to be installed (size is
dependent on two things: 1) amount of water being generates and 2) soil conditions (the
faster that the soil can absorb the effluent the better conditions – therefore, the ideal soil
type of sand)…better conditions = smaller system… or… big flows + slow soils (such as
clay) = big system
When water percolates through the perforated pipes, effluent soaks through the soil
‘and’ is treated by the soil before it reaches the groundwater (i.e. the soil cleans the
water)
Wastewater flows, and consequently, the size of an on-site system that must be built, is
determined by…
1) Number of bedrooms in a house
2) Number of bathrooms in a house
3) Size of the house (bigger house = more entertaining = more drinking = more
flushing)
4) Is NOT judged by the number of people living there as this can change when
a house changes ownership
Basic Septic System
Production
Pretreatment
Disposal
Evapotranspiration
Septic
Tank
Leaching Bed (surrounded by stone)
Soil Absorption
Filtration & Treatment
Groundwater
Streams/Lakes
Measures of Water Quality
BOD (biochemical oxygen demand) – if this is high, the water is dirty, if it is low, the
water is clean, drinking water has a BOD of zero
TSS (total suspended solids) – the greater the TSS, the greater amount of bacteria
present because bacteria likes to ride on solids in the wastewater
E. Coli – some are harmless, but some are very harmful (i.e. one is enough to make you
sick, e.g. Walkerton – E. Coli got into the municipal water supply killing 7 people and
making 1000’s of people sick), this is an indicator organism (indicates the water quality)
Septic tank
-acts as primary treatment
-it is designed so only clear, settled water is allowed to leave the tank to the leaching
bed
-is an oxygen poor environment
Effluent filter
-helps to keep solids from leaving the septic tank on its way to the leaching bed
Leaching bed
-aerobic environment (lots of oxygen, good for allowing microorganisms in the soil to
treat the water)
-has pore spaces filled with oxygen
-treatment of wastewater is physical, biological and chemical
Operation and Maintenance of On-Site Systems
In rural areas, this responsibility falls on the property owner who usually has no training
about how to maintain the system
To maintain…
Pump – every 3 – 5 years
Inspect the tank
Inspect the leaching bed (don’t let the soil on top become compacted)
Ensure that excess water is not going onto the bed
Each system has a life span, typically 20 – 30 years, some signs of system failure would
be…
Sewage backup
Sewage ponding on the leaching bed
Lush growth on the leaching bed