The Lifecycle of an Evans Water Treatment Biosystem

At Evans Equipment & Environmental, we engineer every custom wash bay with three goals in mind: maximize efficiency, minimize environmental and regulatory liability, and extend water reuse as long as possible. 

Winning in this industry isn’t flashy. It’s measured in uptime, readiness, and how fast your crew can get back to work the next morning. And that never happens by accident. 

Through intentional design and calculated flow rates, we customize a water treatment system that works with all available advantages from basic physics to mechanical filtration and biological processes.

To understand what makes the Evans Biosystem different, let’s follow the complete lifecycle of water inside a custom Evans wash bay, starting where the water cycle begins.

The Wash Bay at Work

It begins at the wash. 

High-pressure water is pumped to the pressure washer when the operator cleans the equipment, blasting away dirt, grease, oil, and debris. As soon as that water hits the wash bay floor, gravity takes over, pulling everything toward the center trench drain that runs the length of the wash bay.

Gravity does the initial heavy lifting to guide flow efficiently and predictably into the system. 

Champions don’t fight their infrastructure. They build systems that work with physics, so every wash starts the next job ready to run.

Pre-Treatment Phase 1: Center Trench Drain

The center trench drain is the system’s first stage of pre-treatment.

Traffic-rated grating allows water to fall through while larger debris is slowed and captured. Beneath the trench, water enters the first pit, where heavier suspended solids sink to the bottom. As water continues to enter, partially clarified water rises and spills over a baffle wall into a plated compartment.

Here, even more solids settle out before the water exits through a one-way pipe with a 90-degree bend. This design prevents backflow, so water can only move forward through the system.

As washing continues, water flows at a controlled speed based on your calculated retention time. That is the amount of time water needs to remain in each stage for solids to settle effectively. This is intentional engineering to help your system work smarter, removing as much debris as possible before mechanical or biological treatment even begins.

This is what quiet winning looks like: problems handled early, before they ever reach the rest of the system.

Maintenance Note: Winning systems aren’t lucky. They’re well-maintained. Settled solids must be removed from the pit as part of daily maintenance. We design the center trench to accommodate the size of most excavation tools to streamline the maintenance process. 

Pre-Treatment Phase 2: Mechanical Filtration & Oil-Water Separation

After leaving the trench drain, water is pumped into a three-compartment oil-water separator, where mechanical separation takes place.

At this stage, a coagulant causes finer suspended particles to clump together, making them heavier and easier to remove. Typically, this coagulate is introduced upon initial use of the wash bay. As water moves slowly through each compartment:

• Solids fall to the bottom
• Oil rises to the surface
• Water is drawn from the middle zone, leaving larger contaminants behind
  

This middle draw is critical. It ensures that neither floating oil nor settled solids are carried forward into the treatment system.

In the final compartment, a slotted pipe skims off floating oil and collects it separately for removal. Solids that accumulate at the bottom of each compartment can be periodically flushed through a common return line, sending them back to the front of the system for removal during scheduled cleanouts.

By the time water exits the separator, the majority of solids and free oil have already been removed, protecting the integrity of the biological system downstream.

Water Treatment: The Evans Biosystem

This is where the real water treatment begins. 

Water flows into the Evans Biosystem, a biological treatment process designed to break down remaining grease and hydrocarbons naturally.

Inside the system, reactor compartments are filled with plastic media that provide an ideal surface for living microbes to attach, colonize, and thrive. These microbes do the heavy lifting, consuming contaminants that mechanical systems can’t fully remove.

To keep the environment aerobic, oxygen is continuously supplied through diffusers. This oxygen is critical because it keeps the microbes active and odor-free.

As water flows by gravity through two or more reactor stages (depending on the size of your wash bay), remaining contaminants are biologically broken down. 

This biological process is the heart of the Evans system and the key to long term water reuse.

Maintaining a Healthy Microbe Colony in Every Biosystem

Over time, microbes naturally die off. To maintain peak treatment performance, fresh microbes are injected as needed, ensuring the growth rate always exceeds the die-off rate. This keeps the colony healthy and capable of handling variable wash loads.

Just as important is what doesn’t enter the system. Harsh or caustic chemicals can damage or kill microbial colonies. Evans systems are designed with this in mind, and proper operation guidelines help protect the biological process that makes long-term water reuse possible. 

Post Water Treatment: Processed Water Tank & Continuous Circulation

Once treated, the water reaches the processed water tank where it awaits use in the wash bay.

But the system doesn’t stop just because washing does.

To keep microbes healthy, a small trickle of water continuously circulates back to the beginning of the system, even when the wash bay is idle. This constant movement maintains oxygen levels and prevents stagnation, so the microbial colony never goes dormant.

Consistency is the competitive advantage. When the system never goes dormant, neither does your operation.

Before reuse, the water passes through a final sock filter for added polishing. 

Completing the Loop Back at the Wash Bay

When an operator pulls the trigger on the pressure washer, a drop in pressure inside the air-filled bladder tank signals demand. A pressure switch activates the pump, sending treated water right back to the wash.

And the cycle continues. Clean equipment. Ready crews. Another day won.

This closed-loop system allows Evans wash bays to reuse water for months at a time, dramatically reducing freshwater consumption and extending the time between cleanouts as much as eight to twelve months, depending on usage.

Where the Evans Biosystem Saves You Money

The Evans Biosystem is designed to effectively treat water while reducing the ongoing costs of operating a wash bay. By addressing solids, oil, and contaminants at multiple stages, the system minimizes waste, extends service intervals, and dramatically reduces dependence on fresh water.

Here’s how the savings add up.

Fewer Vacuum Truck Cleanouts

Traditional wash systems allow solids and oils to accumulate quickly, requiring frequent vacuum truck service. Each visit means scheduled downtime, hassle and coordination, and significant expense. The Evans Biosystem can operate for eight to twelve months or longer between cleanouts, depending on your water usage. That translates to fewer service calls, less disruption, and lower annual maintenance costs.

Reduced Freshwater Consumption

Because the Evans system is fully closed-loop, treated water is reused again and again instead of discharged. Facilities can dramatically reduce their reliance on municipal or well water, lowering monthly utility bills and reducing strain on local water infrastructure. In many cases, the only water that needs to be added is what’s lost to evaporation or overspray outside the wash bay. 

Less water in means less water out, and less money spent on both.

Lower Disposal and Compliance Costs

Removing oil and solids in a controlled, staged process reduces the volume of waste that must be hauled off-site and properly disposed of. This not only lowers disposal costs but also reduces regulatory exposure tied to wastewater handling.

Cleaner water inside the system means fewer compliance headaches and a safer, more predictable operation.

Less Downtime, More Productivity

Every time a system is offline for cleaning or repair, productivity takes a hit. By extending service intervals and maintaining consistent water quality, Evans systems keep wash bays operational when you need them most.

Altogether, Evans customs wash bays represent an objectively better return on your investment.

The Result: Smarter Workflow, Longer Reuse, Less Liability

Every drop has a purpose. Every stage is intentional. And every system is engineered to keep your wash bay working smarter, longer, and cleaner. Evans systems protect equipment, reduce environmental risk, and give customers a wash bay that works as hard as they do.