Polyethylene (Poly for short) is the plastic used to make many tanks for power sprayer applications should as pest control and weed control.
Poly tanks are lighter and less expensive than most other types of tanks. They are easy to plumb. Most come with lids and output fittings already installed, which saves time and money. They are usually opaque so the technician can see how much water is in the tank.
On the downside, the tanks generally do not have the life of fiberglass or steel tanks. In my experience, these tanks should last 5 years or more, even in extreme conditions like the AZ sun. The most common problem we see is operator error. For example, when a technician throws a tool in the truck and cracks the tank.
Poly spray tanks are usually one of three styles:
Leg Tank - Designed to bold directly to truck or trailer. Usually comes with steel bands for this purpose. No frame is required, which saves money. Downside - it is difficult to fully drain these tanks because water sits in the legs.
PCO Tank - PCO stands for Pest Control Operator. These tanks are usually square or rectangular. They usually require a frame or some other type of support. The are usually the lowest cost tank.
Elliptical Tank - These tanks are popular because they can be fully drained. The tanks usually sit up in a saddle and are plumbed from the bottom. Many have a sump. These features are beneficial if you are changing materials and need to fully empty the tank.
Poly tanks are a great option for many pest control, weed control and related power spray rig applications.