When it comes to professional window cleaning, spot-free results matter. Nothing diminishes quality faster than water that dries leaving mineral spots or streaks behind. That’s where a RODI system becomes a game changer — and why more window cleaners are switching from basic DI tanks or even conventional squeegee-only methods to water fed pure water technology.

In this post, we’ll break down why RODI systems are essential, how they work, and exactly how to set up and use a 3-stage RODI system featuring a carbon filter, reverse osmosis membrane, and DI cartridge so you can hit the ground running on your next job.

Why Pure Water Matters in Window Cleaning

Traditional tap water contains dissolved solids — minerals like calcium, magnesium, and silica — that leave behind spots once the water evaporates. Streaks and spots not only look unprofessional but create extra work, time, and frustration for window cleaners.

Enter the RODI system. RODI stands for:

• Carbon (C): Activated carbon filter

• Reverse Osmosis (RO): Semi-permeable membrane

• Deionization (DI): Resin cartridge final polish

These three stages work together to strip water of impurities so that the water you spray on windows is nearly 0 TDS (Total Dissolved Solids), meaning the water will evaporate without leaving any residue or spotting behind — a must for professional results.

How the 3-Stage RODI System Works

Here’s what happens as your tap water progresses through a typical 3-stage RODI system:

1. Carbon Filter – The First Line of Defense

The carbon filter removes chlorine and larger contaminants that could damage the RO membrane downstream. Chlorine in water is particularly damaging to RO membranes, so this pre-treatment is essential. 

👉 Think of the carbon filter as the protector of everything that comes next.

2. RO Membrane – Deep Purification

After the carbon stage, water enters the reverse osmosis membrane. Under pressure, water molecules are pushed through a semi-permeable membrane, rejecting up to 90–98%+ of dissolved solids at this stage.

The membrane purifies water by filtering out most dissolved minerals and impurities — but it doesn’t strip everything. That’s where the last stage comes in…

3. DI Cartridge– Final Spot-Free Finish

The DI (Deionization) resin takes whatever’s left and removes the rest of the dissolved solids, bringing your TDS reading down to about zero (0 ppm). 

This final result — 0 TDS water — is what gives window cleaners spot-free results. As the water dries, there’s nothing left to leave behind behind on the glass.

Tools & Supplies You’ll Need for Setup

Before you begin, make sure you have:

✔ A garden hose or hookup from a water source
✔ The RODI cart or system with carbon, RO, and DI stages
✔ TDS meter to measure water quality
✔ Filter wrenches (often included with systems)
✔ Optional pump (if system has low incoming pressure)

Step-by-Step Setup: First-Time Use

Here’s how to get your RODI system up and running the right way.

Unpacking Your ProTool RODI Cart

ProTool HiFlo Pure Water Cart Stainless Steel

$2,326.55

ProTool Cart Stainless Steel Tap Water Pressure Overview: ProTool Cart SS – the epitome of durability and efficiency in pure water systems. Crafted with pride...… read more

When any of your ProTool RODI Carts arrive, there’s no assembly required. Simply remove the packaging and visually inspect the system to ensure all housings, fittings, and tubing are secure from shipping. Because the system is prebuilt, all filtration stages are already installed in the correct order — carbon first, RO membrane second, DI last — so you can move straight to flushing and setup.

This plug-and-play design makes the ProTool line ideal for both new window cleaners and experienced professionals who want a reliable, job-ready RODI system right out of the box.

2. Connect to Water Supply

Attach your water source:

• If you’re at a home or business location, you can connect using a garden hose.

• Some carts allow direct hookup with a diverter or quick connect.

Turn on the water briefly to flush out sediments from the hose before connecting to the system — this protects your filters. Many professional cleaners run the client’s hose dry for ~30 seconds before hooking up. 

3. Flush the Carbon Filter

Before putting the RO membrane into service, run water through the carbon stage for 10–15 minutes. This flushes out any loose carbon fines and activates the filter media. 

Strongly colored or cloudy water at first is normal — it should clear up.

4. Prepare the RO Membrane

Flush the system for at least 30 minutes to properly prep the membrane. This initial flush removes preservatives and preps the membrane for use. 

5. Attach the DI Cartridge

After flushing the RO membrane, connect the water line to the DI cartridge. This stage will finish the purification.

At this point, your system should be plumbed:

Water Source ➞ Carbon ➞ RO Membrane ➞ DI Cartridge➞ TDS Meter / Output to Pole

6. Measure TDS Output

All ProTool Carts come with an Inline TDS meter so you're always with one. If you have a cart without it, use a handheld TDS meter to verify your pure water output. Ideal RODI systems for window cleaning aim for 0 TDS out of the DI.

If you’re reading above 5–10, check pressure, filter orientation, and whether resin might be expired. High RO stage readings often mean the membrane has degraded.

Tips for First Use & Cleaning

Work With a TDS Meter

Bring it with you for every job. If TDS starts to rise, it tells you filters are nearing replacement.

Flush Before & After Each Use

Running water through all stages before and after jobs extends filter life and prevents stagnation.

Monitor Carbon & DI Life

Carbon filters protect the membrane — replace often if you see discoloration. DI resin lasts longer but should be changed when final TDS starts creeping above 0–2 ppm under load.

Common Mistakes to Avoid

❌ Skipping pre-flush: leads to shorter membrane life
❌ Incorrect filter order: reduces purification efficiency
❌ Forgetting to check TDS: you can’t optimize what you don’t measure

Benefits of Using a RODI System

✔ Spot-free windows — no minerals left behind
✔ Faster jobs — less detailing
✔ Less reliance on ladders, chemicals, or labor

Pure water cleaning technology isn’t a fad — it’s now standard practice for professionals aiming to reduce callbacks and deliver premium results. 

Conclusion: Start With a Solid Setup for Spot-Free Success

A properly set up 3-stage RODI (Carbon → RO → DI) system isn’t just a tool — it’s a foundation for quality work in window cleaning. Once dialed in, it consistently produces the purest water possible, making your job faster, easier, and more professional.

Follow the steps above, measure your output, and maintain your filters — and you’ll have spot-free glass without a second thought.