When planning a commercial space that requires a grease interceptor, it’s vital to adhere to building codes and local ordinances. It’s also important to decide on what type of material your grease interceptor should be, as there are a number of factors to consider in selecting the appropriate product.

Traditional metal interceptors can be subject to corrosion due to the high pH levels in waste water. Therefore plumbing manufacturers have started using more durable materials for their products. Each material offers benefits and varying life expectancies. Let’s take a look at the options.

Cement

Traditional cement interceptors range in size from 300 gallons to several thousand. They can be buried and paved over, which makes them conveniently out of the way, but makes repairing, replacing, and maintaining them difficult. They can also be more easily integrated into areas where a large-volume interceptor would be difficult to install. Cement interceptors need to be replaced every 5-10 years. With these large sized units, the cost of replacing them is steep. 

While cement is a relatively cheap material to use, it’s susceptible to corrosion and cracking due to factors in its natural environment. From the freezing and thawing through the seasons to the internal corrosion from the acidic moisture, the life expectancy of a cement interceptor is not long.

Cast Iron

While cast iron interceptors are characterized by a high degree of strength, they are very expensive to produce, have a lower corrosion-resistance, and the finish is poor: approximately half of all castings are scrapped. Combined with the extreme weight and short life expectancy of expensive pattern equipment, most manufacturers have switched to different materials.

Steel

Steel/Stainless Steel interceptors with an epoxy coating are very common these days and have replaced traditional cast iron interceptors. The steel external shell is more durable to impact, lower cost and lighter than the concrete and cast-iron options. Most steel interceptors are epoxy coated which is more hygienic than concrete or cast iron and is easier to clean and maintain. They are more resistant to corrosion, fire & heat and can withstand high loading without failing (although the high temperature will degrade the epoxy coating).

They do have relatively short lifespans and will typically need to be replaced every 5 years making the replacement costs quite high.

Plastic

Plastic grease interceptors are a great option for both hydromechanical and gravity interceptors. Typically, high density polyethylene (HDPE) is the material used and HDPE interceptors have a greater resistance to chemicals and will not crack, chip or bulge under the extreme impact, sunlight and/or temperature changes. 

HDPE is not quite as strong as cement, cast iron or steel, so often cannot withstand high loads on the interceptor without extra support. Certain Municipalities may have specific installation practices to comply with their local perspective. Always double check with the AHJ in your area.