Living area (m2) (all living space, excluding basement) If your total is greater then 20, calculate the additional flow of 50 L for each additional fixture over 20 (round up for each half)įor example, if your total is 23, then you may have to add 150 L to the bedroom base rate. Use the chart below to figure out the number of fixtures: If the total fixture count exceeds 20, then 50 L per additional fixture will need to be added to the bedroom base rate. The greater of these calculations will need to be added, as opposed to both being added. The OBC refers to the Maximum Daily Flow as “Q” for all calculations.įigure out if the number of fixtures (bathrooms, sinks, etc) OR total living space will also need to be calculated to ADD additional L/day to the base bedroom rate. Average daily use per person is approximately 275 L, and therefore, the maximum daily flow could be around 500-600 L / bedroom.ĥ Bedrooms – 2500 L (If you are building a home with more then 5 bedrooms, consult a professional) The OBC assumes that for every bedroom, 2 people could be living in the residence. Most people assume it is based on the number of bathrooms or current occupants, but that is not the case. Step 1: Calculate the maximum daily flow, as per the OBC calculation.Īll daily flow calculations start with the number of bedrooms. The two main factors that dictate the size and design of a septic system are the maximum daily flow and soil/site conditions. Local governing authorities may have additional by-laws in place requiring additional design requirements. The following guide has been put together to assist you with meeting minimum OBC regulations for residential septic systems. It is the homeowners responsibility to contact local governing authorities and acquire the necessary permits associated with the septic system installation or repair. The system must be built to meet the maximum use possibility of the residence in case the property is sold to new owners or changed from seasonal use to a year round residence.
The average 3-4 bedroom house is rated at 2000L.Īll systems must be built according to the OBC regardless of how the residence will be used such as seasonal cottage use or low occupancy numbers. Here is a quick guide to help you with how to design a new system.Īll septic systems that are within a single lot and rated to accept a total daily flow rate of <10,000 L must comply with the Ontario Building Code (OBC). The building code can be quite intimidating and confusing. Or both phone and email at 90 or to interpret the code! Additioanl Concrete Septic Tank information and drawings are also available on our website.įor additional questions you may have, we’re here to help on-site at 5377 Elcho Road, Wellandport. If you’re looking to learn about how to calculate the best septic tank and septic tank bed for your needs, this guide is for you. The original article was found at ontarioseptictank.ca
Therefore, the minimum size septic tank required for this example is 2,750L.Septic Tanks – Ontario Building Code Explained Step 3: Add 2,000L to your litres produced per dayĬarrying on with the example above: 750L (step 2) + 2,000L = 2,750L To calculate the number of litres per day for your property, just multiply the number of people x 150L.Įxample: three bedrooms house = 5P (see step 1) Step 2: Calculate the number of litres of wastewater produced per dayīritish Water estimates that one person creates 150L per day. *Reference: Flows & loads from British Water for larger domestic housing, commercial and industrial premises. House with five bedrooms = minimum 7P system (5+2)Ī house with six bedrooms = minimum 8P system (5+3) House with three bedrooms = minimum 5P systemĪ house with four bedrooms = minimum 6P system (5+1) Single house – up to and including three bedrooms: P = 5, add 1 P for each bedroom thereafter. Small one and two-bedroom houses or flatsįlat with one bedroom = minimum 3P systemįlat with two bedrooms = minimum 4P system **Please note that the abbreviation for Minimum Population is “P” *Reference: Flows & Loads from British Water
This is calculated based on the number of bedrooms in your home. The volume of effluent coming from your house is determined by the number of people using the system. Step 1: Determine “P” (Minimum Population) from the number of bedrooms you have