Plastic or Concrete Soak Pits? Here’s Why Concrete Wins
When it comes to soak pits for stormwater management, you’ve really only got two choices: plastic or concrete. Plastic soak pits—usually made from polypropylene—have become more common in recent years because they’re lightweight and easy to ship. But when you look at the full picture, concrete soak pits come out on top every time. Here’s why:
1. Concrete is Built to Last
Concrete soak pits are designed with a 100-year lifespan—and in many cases, they’ll last even longer. They hold their shape, don’t warp or collapse, and can handle tough site conditions. Polypropylene plastic, on the other hand, breaks down over time releasing microplastics and doesn’t have the same structural integrity, especially under pressure.
2. Stronger Under Load
This is where concrete really shines. It can easily handle the weight of soil, vehicles, or heavy equipment without cracking or shifting. Plastic soak pits can’t take the same loads. To make them work in trafficable areas, you need to dig them in deeper and pile more fill on top just to get enough cover. That means bigger holes, more excavation, and more material to cart away.
3. Faster and Easier to Install
Plastic soak pits typically come in flat packs and need to be built by hand on-site. It’s fiddly and labour-intensive. Concrete soak pits show up ready to go—just lower them into place, hook up the pipes, and backfill. Simple as that. It’s a big time-saver, especially on bigger jobs.
4. Better for the Environment
Concrete is an inert material—it won’t leach anything into the soil or groundwater. Polypropylene plastic, over time, can break down and release microplastics or other unwanted substances into the surrounding ground. If sustainability matters on your project, that’s a key difference.
5. A Smarter Long-Term Investment
Yes, concrete soak pits cost more in materials than plastic—but that’s only part of the story. Plastic soak pits are labour-intensive to assemble, and to make them strong enough for traffic, they need to be buried deeper. That means more excavation, more expensive fill to import, and more to dump—none of which is cheap these days. Add in the extra time on-site and it all adds up quickly. And to top it off, concrete soak pits last significantly longer. So when you look at the full picture, concrete is actually the cheaper investment over time.
6. Easier to Maintain
Concrete soak pits are designed with access in mind. You can simply lift the lid and clean out any debris or sediment that builds up over time—no digging, no dismantling. Plastic soak pits often don’t have accessible lids or chambers, making maintenance a real challenge once they’re in the ground. That can lead to blockages or reduced performance down the line, especially in areas with high sediment or leaf loads.
The Verdict? Concrete Wins.
If you’re after a soak pit that’s durable, fast and simple to install, environmentally safe, and built to last, concrete is hands-down the better choice. Whether you’re a contractor, developer, or council, it’s the smart call for long-term performance and peace of mind.
