Design & DIY

Choose the right waste-water system

Septic system pipes on a gravel bed Photo by Stephen Farhall/Shutterstock

Kicking back after a barbecue, comparing treatment systems. We’ve all done it. But there’s no ideal, one-fits-all solution. Here are some options.

Option #1 A conventional septic system

Best for large, level lots with deep, well-drained soils
Cost $15K–$40K (for this and all systems, depending on cottage size, soils, lot, and access)

“The soils you have will tell you what you need,” says Alberta septic designer Daniel Morris. Deep, permeable soils on a flat or gently sloping lot may be whispering “conventional septic.” The typical setup includes a double-chambered concrete, plastic, or fibreglass tank and a distribution system, a.k.a. the leaching, tile, or area bed, or treatment field, where effluent from the tank seeps from pipes or infiltration chambers into sand, gravel, and soil. Modern systems have an effluent filter to screen out solids (a good retrofit for older systems; a requirement in Alberta) and often a distribution box to ensure the pipes get equal access to the tank’s output. The effluent must take at least a week to work through the soil’s natural filter before hitting the water table, says Lesley Desjardins of the Western Canada Onsite Wastewater Management Association. By then, effluent should meet public swimming standards, if not better.

Costs vary by site, but B.C. waste-water engineer Ian Ralston suggests that the near-mythical “perfect site” with the “cheapest possible system” might be a rock-bottom $8,000. More likely, though, you’re looking at twice that much. And water access can double the cost for even simple installations.

Option #2 An advanced treatment system

Best for small lots, difficult soil conditions, limited access, lots with many trees
Cost $18K–$35K

The problem with the “perfect site” is that there just aren’t that many left in popular cottage areas. In Central Ontario’s Simcoe County, “what’s left are forested lots, where no one wants to cut the trees, or land with a high water table, or tiny little building lots,” says Peter Head, of HeadStart Construction.

Throw in a layer of subsurface clay and plenty of islands, and about 60 per cent of Head’s septic installations end up being advanced treatment units. Once known as “tertiary treatments,” these leading-edge septics started showing up in the 1990s. Advanced units produce cleaner effluent before it’s dispersed, so they require a smaller dispersal zone for final treatment, allowing the system to fit in tighter areas. To cite an example in Ontario’s code, an advanced treatment dispersal area could be a third smaller than a conventional bed—22 sq. metres, compared to 33. A smaller field means there’s more room for a new or larger cottage and may trim costs for remote locations and sites where installers have to barge or truck aggregate in for area beds.

While an advanced system may mean fewer tank pump-outs—the Waterloo Biofilter produces only about half the sludge of a conventional tank, says Chris Jowett, the company’s head of technology and government relations—the units typically require a maintenance contract and testing. George Maconachie pays about $150 to have his system, made by Ecoflo, inspected at his Bass Lake, Ont., property. The annual visit includes effluent sampling, inspection of the mechanical components, and an assessment of the filter’s remaining life. Think of it as basic preventative maintenance that prolongs the life of your system and makes sure it’s running smoothly, says Madeline Szöts, the marketing and communications director for Premier Tech Aqua, makers of the Ecoflo.

This sort of maintenance is typically required by municipal building departments or septic regulators, but it’s good insurance for anyone with an advanced system. Some units pump air to foster an aerobic environment (such as the Norweco Hydro-Kinetic). Others force effluent through micro-filtering membranes (BioMicrobics BioBarrier) or trickle or pulse liquid through “filter media,” including sand and gravel, synthetic foams (the Waterloo Biofilter), coconut husk fibre, or a mix of coco fibre and peat moss (the EcoFlo), or fabrics with surfaces housing large microbial population (including two non-mechanical systems that combine treatment with dispersal, the Eljen Geotextile Sand Filter and the Make Way Enviro-Septic).

Another innovative approach to effluent dispersal is the LFH At-Grade system. Originally designed for wooded lots in northern and central Alberta, the layout uses a pipe suspended just above the forest floor, protected by a plastic distribution chamber and covered with a mound of wood chips and bark mulch. Cost is comparable to other approaches, and the basic technology is similar to a shallow buried trench. “There’s very little disruption to the landscape,” says Morris, because the system snakes between trees and is installed over the surface. As vegetation grows around the mulch, the system becomes nearly invisible.

Costs for an advanced system tend to be submerged in the installer’s overall estimate, but generally, says Jowett, the treatment system is about a third of the bill. The rest is split between the other components (tank, stone and sand, pipes) and installation and permits.

Option #3 A grey-water system

Best for a cottage without pressurized water and relying on a privy or an alternative toilet
Cost $2.5K–$10K

“People come to me looking for a grey-water system and a composting toilet, with the thought that it will be extremely cheap,” says Ian Ralston. “They’re usually disappointed.”

Even with an alterna-toilet to look after their sewage (or “black water”), cottagers still require a grey-water system to handle the melange of water, soap, hair, grease, food particles, and skin cells sluicing from sinks or showers. A common option for cottages with running water is a scaled-down septic system, complete with tank and area bed. The traditional, if more rustic, Ontario solution is a seepage pit constructed from unmortared concrete blocks, bricks, or pressure-treated wood in a bed of gravel. As an added wrinkle, if you’ve plumbed your composting toilet with an overflow pipe (recommended on many models, in case you get too much water in the system), you’ll need to connect that to an appropriate disposal too. In Ontario, that’s either a septic system or a “class three cesspool,” which looks much like a second grey-water pit. 

Eric Kohlsmith, a septic inspector for the Rideau Valley Conservation Authority, thinks a grey-water system is a great alternative for a rustic cottage, but says that most cottagers, faced with the costs, opt for a full septic system. “The day of the old 55-gallon drum in the ground for a grey-water pit is gone. Now, that’s just too small,” he says, though it’s still legal. “Why not spend a little bit more and get a fully functioning system?” And as North Bay–area installer Neil Jones adds, full septic systems tend to boost a cottage’s resale value.

Option #4 A holding tank

Best for road-access cottages with small lots, high water tables, or porous soils where no other system fits
Cost $7K–$10K

A holding tank is one option for sites where coarse soils allow septic effluent to percolate towards the water table too quickly. When Jodi and Darryl Enns built their Pelican Lake, Man., cottage, subsurface shale stone made a conventional septic unworkable. To keep effluent from the lake, they installed a 2,500-gallon plastic tank and a macerating sewage pump at a cost of about $9,000.

The Enns are lucky to have cheap pump-outs ($50), but the bill to pump out a tank’s slurry for treatment is more commonly $75 to $150, says Bernie Dyck of B&L Septic in Saskatoon. If you’re pumping more than once or twice a year (and frequent cottagers with large families could be pumping monthly, or even more often), low-flow toilets will pay for themselves. And a grey-water recycling system—filtering and treating drain water for reuse in the toilet—may make sense if you’re building a large new cottage with a couple of showers. Options include the BioMicrobics Recover unit (about $3,400 U.S., plus installation) and the Greyter system ($4,250).

Holding tanks are also an option when a full septic won’t fit within regulated setbacks. In Saskatchewan, “absorption fields” (a.k.a. dispersal areas) must be at least 500 feet from the high-water mark, so sandy soils, lot sizes, and regulations tend to push cottagers towards holding tanks. But as any child told to “just hold it” on a long cottage drive knows, leakage can occur, especially with older tanks. Partly for that reason, in much of Canada, says Scott Saunders of Drain Bros. Excavating in Campbellford, Ont., holding tanks remain “a last option.”


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