Professional engineered septic system design for homes, cottages and businesses across Ontario. Septic design, soil T-time testing and the septic permit, all done by one firm — for new and replacement systems.
Outside a sewered area, every home and business needs its own sewage system, and in Ontario that system has to be designed to suit the lot and the soil, then approved before it is built. The design is what the approval, and the installer, work from.
An engineered septic design starts with a site assessment and a soil T-time test, which measures how quickly the ground drains. From that we size the tank and the leaching bed to the building, prepare permit-ready drawings, and submit the septic permit application to the authority that covers your property. Where the lot or soil needs it, we design an advanced treatment system instead of a conventional bed.
Many septic designers do not do the soil test themselves: the T-time is handed to a separate geotechnical company, which you have to schedule and wait for. King EPCM does the design, the T-time test and the permit application in-house, so the whole job is one scope with one point of contact.
We provide this for new homes and additions on rural and large-lot properties, for failed or ageing systems that need replacing, and for commercial and industrial properties.
| New systemHome, cottage, addition | Replacement systemFailed or ageing bed | Large systemOver 10,000 L/day | |
|---|---|---|---|
| When | A new building, or an addition that adds bedrooms or flow, on a lot with no municipal sewer | The existing bed has failed, is at the end of its life, or no longer suits the building | Commercial, industrial or institutional flows above the Building Code threshold |
| What we do | Site assessment, T-time test, sizing, design, permit application | Re-assess the site and soil, design the replacement, apply for the new permit | Hydrogeological assessment, system design and the provincial approval application |
| Who approves it | Your local principal authority — depending on the municipality, the building department, the health unit or the conservation authority | The Ministry of the Environment, Conservation and Parks (MECP), through an Environmental Compliance Approval (ECA) | |
| Governing rules | Ontario Building Code, Part 8 | Ontario Water Resources Act — see our LSSDS guide | |
One scope covers the field work, the engineering and the paperwork, so you are not coordinating a soil tester, a designer and a permit expediter separately. Before anything is drawn we confirm you actually need a septic system, and whether an existing one can be kept.
The T-time is the number everything else hangs on. It is the soil’s percolation time in minutes per centimetre: a low T-time means fast-draining soil and a smaller bed, a high T-time means slow soil and a larger bed or an alternative system. Our own field team measures it on site, along with the well location, groundwater and the setbacks that limit where a bed can go, so the design fits the ground it will sit in. Read our guide to percolation tests, T-time and infiltration rates.
You choose the trade-off. Septic systems range from a conventional in-ground or raised bed to advanced treatment units with nothing visible above ground. Our starting point is always the cheapest, best-quality bed that fits your yard; where the usable area is not enough, we add treatment technology to make up for it. Your priorities form tells us whether lowest cost, best value or highest quality matters most, and we present up to three options that fit the lot and the soil, so you decide with the costs and the look of the yard in front of you.
Who issues the permit varies by municipality: it may be the building department, the public health unit or the conservation authority. We confirm the right authority for your property, assemble the permit package and prepare the application to its requirements.
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How we help
We assess the lot, test the soil, size and design the system (or check whether the existing system can take the addition), and submit the septic permit application so the building permit can proceed.
← BackHow we help
We re-assess the site and soil, design the replacement system to suit what is there now, and handle the permit application.
← BackHow we help
We confirm whether the flow stays under the Building Code or crosses the 10,000 L/day line, then design and permit the system accordingly.
← BackA septic design is only as good as the soil data under it and the approval it earns. Most design firms do not do the soil test themselves and bring in a separate geotechnical company for the T-time. King EPCM does septic design, T-time testing and permitting together: our own crew tests the soil, so the bed is sized to measured ground, not an assumption, and we prepare the permit application and deal with the reviewing authority ourselves.
Our designs are engineered, prepared by a licensed P.Eng.: reliable, compliant and cost-effective, tailored to the property conditions and the regulatory requirements. Because civil design, geotechnical and hydrogeology sit under one roof, the same team can take a project from a simple residential bed to a large system that needs a provincial approval.
Ontario's Building Code allows some small residential systems to be designed by a licensed sewage system designer rather than an engineer. In practice, an engineered design is what most building departments, health units and lenders expect for a new or replacement system, and it is the usual route for commercial, industrial and multi-unit properties. Large systems over 10,000 litres per day are approved by the province and need supporting studies prepared by a P.Eng. or P.Geo. King EPCM provides engineered septic designs for all of these.
A percolation test measures how quickly water moves through the soil on your property. For septic design the result is expressed as a T-time, in minutes per centimetre. A lower T-time means faster-draining soil. The T-time sets the size and type of leaching bed your property needs, so it is one of the first things we measure during the site visit. More in our T-time guide.
It varies by municipality. Depending on where the property is, septic permits are issued by the local building department, the public health unit or the conservation authority. We confirm the right authority for your property and prepare the application to its requirements.
Once the application is submitted, approval typically takes about 2 to 4 weeks. It depends on the municipality and on other factors, in particular whether a conservation authority permit is also needed. We confirm the likely timeline for your property when we quote.
Whatever the lot and the soil allow: conventional in-ground and raised filter beds and absorption trenches, Type A beds, shallow buried trenches, and advanced treatment units such as Eljen GSF, Bionest and Waterloo biofilter systems, with or without a visible above-ground unit. A holding tank is designed only where nothing else is permitted. We present the options that fit your property and let you choose on cost, maintenance and the look of the yard.
Yes. Replacing a failed septic bed or system needs a new design and a new permit, and King EPCM handles both. We assess the site and soil, design the replacement system, and prepare the permit application.
General information only — not engineering advice for a specific property, and no substitute for the current Ontario Building Code or the requirements of the authority having jurisdiction. Confirm the rules for your site with a qualified professional.
Send us the address and we'll tell you what the design and permit will involve — with a clear quote within 3 business days.
Request a QuoteTell us the property address, whether it is a new or replacement system, and what you are building. We'll confirm the scope and send you a clear quote within 3 business days.
Call us during business hours.
416-342-30013780 14th Avenue, Unit 211
Markham, ON L3R 9Y5