How to Properly Store DEF (Diesel Exhaust Fluid)

If you operate diesel-powered trucks, off-road equipment, or a commercial fleet, Diesel Exhaust Fluid (DEF) is a critical part of your day-to-day operations. But what many operators don’t realize is that how you store DEF directly affects its performance, shelf life, and your equipment’s efficiency.

At Susquehanna Sales & Services, we help businesses not only source high-quality DEF, but also understand how to handle it correctly — especially when buying in bulk. Here’s everything you need to know about proper DEF storage to protect your investment and ensure smooth engine performance.

Why Storage Matters with DEF

DEF is a non-toxic solution made of 32.5% urea and 67.5% deionized water, used in selective catalytic reduction (SCR) systems to reduce nitrogen oxide (NOx) emissions. But it’s sensitive to:

• Temperature changes

• Contamination

• UV light exposure

Incorrect storage can lead to:

• Degraded fluid quality

• Equipment malfunctions

• Costly SCR system damage

• Failed emissions compliance

Good DEF is clear, colorless, and free from particles or odor. If it looks cloudy or has sediment, it may be compromised.

Control Temperature

DEF has a recommended storage temperature between 12°F and 86°F.

• If DEF freezes (below 12°F), it can expand by up to 7% — which may damage sealed containers if not designed to handle expansion. The good news: frozen DEF is still usable once thawed.

• If DEF is exposed to high heat (above 86°F) for long periods, the urea concentration may break down, making it ineffective and shortening its shelf life.

Best Practice: Store DEF indoors or in a temperature-controlled shed or DEF cabinet when possible. Use insulated totes or drums for outdoor storage.

Keep It Clean and Sealed

Contamination — even from a small amount of dirt, dust, fuel, or tap water — can ruin DEF and damage your vehicle’s SCR system.

Avoid:

• Using containers that previously held oil or chemicals

• Transferring DEF with unapproved hoses or nozzles

• Leaving totes or jugs open to the air

Best Practice: Always use dedicated DEF dispensing equipment. Keep containers sealed and use closed systems for transfers.

Protect from Sunlight

UV light can degrade the chemical composition of DEF over time. Clear or translucent containers may allow sunlight to enter and break down the solution.

Best Practice: Use opaque or UV-protected storage containers. Store DEF away from direct sunlight, even when kept indoors.

Understand Shelf Life

When stored properly:

• DEF has a shelf life of 12 months, possibly up to 24 months in cool, stable environments.

• Expired or improperly stored DEF may lose its potency and cause error codes or damage to SCR components.

Check the manufacturing date on bulk DEF containers, and rotate older stock first.

Best Practice: Track usage and order only what your operation can use within 6–12 months. Use FIFO (First In, First Out) inventory methods.

Use the Right Equipment

If you're storing or dispensing DEF from drums, totes, or bulk tanks, make sure you're using equipment designed for DEF — including:

• Stainless steel or DEF-grade plastic pumps and nozzles

• Sealed delivery systems with no exposure to air

• Properly labeled containers to avoid mix-ups

Never use galvanized steel, copper, or brass fittings — they will react with DEF and cause contamination.

Keep Your Equipment Running Right

Whether you manage a fleet of trucks, a construction crew, or agricultural equipment, the way you store your DEF has a direct impact on performance, emissions compliance, and maintenance costs.

At Susquehanna Sales & Services, we supply DEF in bulk, totes, drums, and jugs, along with pumps, storage equipment, and maintenance advice to help you get the most out of your investment.

Contact us today to order DEF or learn more about safe storage solutions that protect your equipment — and your bottom line.