Designing a septic system is a job that's often best left to professionals. While you may be able to choose a few aspects of your system design, you'll usually want to rely on an experienced septic contractor to guide you through the process. However, there is one decision you'll typically need to make, and that's what type of tank material you'd like to use.
Modern septic tanks come in various designs, but polyethylene (poly) and concrete tanks are two of the most common options. Poly tanks (or plastic tanks) are a lightweight alternative to concrete and an option many homeowners choose, but which is right for your property? There's no correct answer for every situation, but this guide will help you understand the advantages of each.
Concrete — Traditional, Heavy, Long-Lasting, Pricy
Most older septic systems still use concrete tanks, but this is a form of survivorship bias. Concrete and steel were both common options in the past, but steel tanks have a predictable problem: rust. Steel septic tanks are still available, but many in current homes are relatively new. Since steel has a much lower lifespan than concrete, you're less likely to find older steel tanks still in service.
In fact, longevity is the primary advantage of concrete. Concrete tanks can last for decades and are generally okay to use in any environment, regardless of local regulations or building codes. Concrete tanks are also less likely to interact with local soil or water conditions, so they're suitable in areas where steel or other materials may degrade more quickly.
However, concrete is also heavy and typically requires heavy equipment to move into place. As a result, concrete tanks are sometimes unsuitable for challenging installation locations, although many contractors will have equipment that can reach even tight areas. Cost is another potential downside, with concrete tanks often being more expensive than alternatives.
Poly — Reliable, Light, Small, Inexpensive
Poly tanks are a newer alternative to concrete with several potential advantages. These lightweight plastic tanks are easier to install, allowing contractors to place them in locations inaccessible to heavy equipment. They're also fairly reliable since seamless designs have few locations where leaks can develop. Poly tanks also tend to cost less than traditional concrete options.
The two primary downsides to plastic tanks are size and lifespan. Modern seamless tanks are typically only available in smaller sizes, making them less suitable for large houses with many residents. Plastic tanks typically have a shorter lifespan than concrete, although you can expect several decades from a high-quality, properly installed plastic tank.
The best tank for your property will depend on numerous factors, including your budget, the size of your home, and your intended installation location. By understanding the differences between tank types and discussing your options with a qualified installer, you should be able to select a tank that works perfectly for your needs.
Contact a professional for more information about septic system installation.