Septic System Installation

When you need a new septic system

A full septic system installation usually happens for one of three reasons: you are building on a rural lot with no sewer, the existing system has failed beyond repair, or an addition pushes the house past what the old system was sized for. Each starts the same way, with a look at the soil and a design that suits it. The septic system cost guide has a wider look at budgets, and the septic cost calculator gives a rough range for your situation.

The system classes in Ontario

Part 8 of the Ontario Building Code sorts sewage systems into classes. For a house, two matter. A Class 4 system is a treatment unit, most often a septic tank, followed by a leaching bed that disperses the effluent into the soil. A Class 5 system is a holding tank with no outlet, pumped by truck. Most new rural homes get a Class 4 system; holding tanks are generally kept for cases where a bed cannot work. The guide comparing a holding tank and a septic tank explains that choice.

Within Class 4 there are several bed designs:

• Conventional in-ground bed: perforated pipe in stone trenches set into native soil. The simplest and cheapest, but only where the soil drains well enough.
• Partially raised bed: part of the bed sits in native soil and part in imported sand, used where the native soil is marginal or bedrock or groundwater is near the surface.
• Fully raised, fill-based bed: the whole bed is built up on imported sand above grade, with a mantle around it. This is common on the heavy clay found across much of Glanbrook, Haldimand and West Lincoln.
• Filter bed: effluent passes through a layer of specified sand before reaching the soil, which allows a smaller footprint.
• Tertiary treatment unit: a pre-engineered unit such as a Waterloo Biofilter or an Ecoflo, which cleans the effluent much further before it reaches a reduced bed. Useful on small lots, near water, or on poor soil.

Why soil decides the design

The key measurement is percolation time, called the T-time: the number of minutes water takes to drop one centimetre in the soil. Sandy loam might take a few minutes; dense clay can take far longer than the range the Building Code allows for a conventional bed. Much of the area south and east of Hamilton sits on the Haldimand Clay Plain, which is why raised beds are such a familiar sight in Haldimand County and around Binbrook and Glanbrook. Bringing in sand adds cost, but it gives the effluent something it can actually soak into.

The designer also looks at the depth to groundwater and bedrock, the slope, the location of wells (yours and the neighbours’), watercourses, property lines and the house itself. The Building Code sets minimum clearances from all of them.

Design, permit and inspections

A sewage system design must be prepared by someone who holds the on-site sewage systems qualification under the Building Code (a BCIN), or by a professional engineer. The design goes to the building department that issues Part 8 permits for your municipality, and no excavation should start until that permit is issued. During the job, the inspector visits before the tank and bed are covered, and the system cannot be used until it passes. Our page on Ontario septic system rules explains how permits are handled across the region.

What happens on site

1. Test pits or a soil sample confirm the conditions in the design.
2. Stakes mark the tank, bed and mantle, with clearances checked.
3. The tank goes in, set level, with the inlet from the house connected.
4. For a raised bed, sand fill is placed and compacted in lifts before the stone and distribution pipe go down.
5. The inspector checks the open work.
6. The system is covered, topsoiled and seeded, and lids or risers are left at grade for future pumping.

A straightforward job is often a week or two on site once the permit is in hand. Wet weather on clay can stretch that, because heavy machines rut saturated ground and compaction ruins a bed before it starts working.

What moves the price

Fill is the biggest swing factor: a raised bed on clay can need many truckloads of sand. Lot access, distance from the house, the number of bedrooms the system must serve, any need for an effluent pump to lift water up to a raised bed, and the choice of a tertiary unit all add up. Landscaping restoration is sometimes priced separately.

Getting started

Septic Hamilton is a referral service. You request septic service with the address, whether this is new construction or a replacement, and any drawings you already have. We pass it to one qualified installer who works in your area, and they arrange the site visit, design and quote. You deal with them directly from there.