DI vs RO Waterfed Systems | Which Pure Water System Is Right? | Hygiene Direct NZ
DI vs RO Waterfed Systems: Which Pure Water System Is Right for You?
Understanding the Difference Between Deionisation and Reverse Osmosis for Professional Window Cleaning
If you're investing in a waterfed pole system, one of the biggest decisions you'll make is choosing the right method of water purification.
Should you choose a DI (Deionisation) system, an RO (Reverse Osmosis) system, or a combination of both?
The answer depends on several factors, including your local water quality, how much purified water you use each day, whether you're working from a vehicle or carrying your equipment between jobs, and how quickly you want to recover your investment.
In this guide, we'll explain exactly how both systems work, compare their advantages and disadvantages, and help you decide which option is best for your business.
If you're new to pure water window cleaning, we recommend reading these guides first:
Complete Guide to Waterfed Pole Systems
How Waterfed Pole Systems Work
Pure Water Window Cleaning Explained
Why Does Water Quality Matter?
The whole purpose of a waterfed system is to produce spot-free windows.
Unfortunately, ordinary tap water contains dissolved minerals including:
- Calcium
- Magnesium
- Sodium
- Iron
- Silica
When tap water dries on glass, these minerals remain behind as visible spots and streaks.
Both DI and RO systems remove these dissolved solids before the water reaches your pole, allowing windows to dry naturally without leaving mineral deposits.
Browse Hygiene Direct's complete range of Waterfed Systems & Equipment:
What Is a DI System?
DI stands for Deionisation.
A DI system passes water through a cylinder containing specialist ion exchange resin.
As the water flows through the resin, dissolved mineral ions are removed, producing highly purified water suitable for professional window cleaning.
Because DI systems have very few moving parts, they are extremely popular with window cleaners wanting a simple, reliable setup.
Advantages of DI Systems
DI systems are ideal for many professional window cleaners because they are:
- Lightweight
- Portable
- Easy to transport
- Quick to set up
- Low maintenance
- Excellent for mobile operators
Many businesses can begin producing pure water within minutes.
Browse our Pure Water DI Systems & Parts
Browse our HyGenie DI Systems & Parts
Browse our DI Bundles
When Is a DI System the Best Choice?
A DI system is often the best choice if you:
- Clean residential homes
- Clean small commercial buildings
- Travel between multiple jobs
- Need a portable setup
- Produce moderate amounts of pure water
- Have relatively low TDS tap water
For many New Zealand window cleaners, a portable DI system is the simplest way to start using waterfed technology.
What Is an RO System?
RO stands for Reverse Osmosis.
Rather than relying solely on resin, an RO system forces water through a microscopic membrane.
This membrane removes the majority of dissolved minerals before the water reaches a final polishing stage.
Most professional RO systems include:
- Sediment filter
- Carbon filter
- Reverse Osmosis membrane
- DI polishing resin
The final DI stage removes any remaining dissolved minerals to produce exceptionally pure water.
Advantages of RO Systems
RO systems really come into their own when large volumes of purified water are required.
Benefits include:
- Lower long-term resin costs
- Excellent for high TDS water
- Produces large volumes of pure water
- Ideal for commercial window cleaning businesses
- Better suited to permanent vehicle installations
Although the initial purchase cost is higher, the reduced resin consumption often makes RO systems more economical over time.
DI vs RO Comparison
| Feature | DI System | RO System |
|---|---|---|
| Purchase Cost | Lower | Higher |
| Running Costs | Higher resin use | Lower resin use |
| Portability | Excellent | Usually vehicle or workshop based |
| Ease of Setup | Very simple | More complex |
| Maintenance | Replace resin | Replace filters, membrane & resin |
| Best Water Quality | Low–Moderate TDS | Moderate–High TDS |
| Best For | Mobile window cleaners | High volume commercial cleaning |
What Is TDS?
TDS stands for Total Dissolved Solids.
It measures how many dissolved minerals are present in your source water.
The higher your TDS reading:
- The harder your water
- The faster DI resin becomes exhausted
- The more economical RO filtration becomes
Professional window cleaners regularly check TDS to ensure they continue producing high-quality pure water.
Browse DI Accessories & TDS Meters
Can You Combine DI and RO?
Absolutely.
In fact, this is exactly what many professional systems do.
The process looks like this:
Tap Water
↓
Sediment Filter
↓
Carbon Filter
↓
RO Membrane
↓
DI Resin
↓
Pure Water
↓
Waterfed Pole
↓
Spot-Free Windows
The RO membrane removes most dissolved solids.
The DI resin then "polishes" the remaining water to produce an exceptionally low TDS reading.
This combination reduces resin consumption while still producing premium-quality pure water.
Which System Will Cost Less to Run?
This depends entirely on your water.
If your tap water has a relatively low TDS reading, a DI system may be the most economical option.
If your TDS is high, DI resin becomes exhausted much faster.
Adding an RO membrane dramatically reduces the workload placed on the resin, helping reduce long-term operating costs.
Which Industries Use RO and DI Systems?
Professional pure water systems are widely used by:
- Window cleaning companies
- Schools
- Universities
- Hospitals
- Retirement villages
- Shopping centres
- Commercial property managers
- Hotels
- Industrial sites
- Government buildings
Wherever regular exterior window cleaning is required, choosing the correct purification system helps improve cleaning quality and productivity.
Common Buying Mistakes
Many first-time buyers make similar mistakes.
Buying Before Testing Water Quality
Always test your local water before deciding between DI and RO.
Choosing Only on Purchase Price
The cheapest system isn't always the cheapest to own.
Ignoring Resin Costs
Running costs vary significantly depending on local water quality.
Not Planning for Business Growth
Choose equipment that will continue meeting your needs as your customer base grows.
Which Hygiene Direct Products Should You Look At?
To build a complete professional waterfed setup, browse:
Why Buy from Hygiene Direct?
At Hygiene Direct, we don't simply sell equipment—we help businesses choose the right solution.
Our experienced team can recommend the ideal system based on:
- Your water quality
- The height of the buildings you clean
- Expected daily water usage
- Budget
- Business growth plans
As a proudly New Zealand-owned company with locally owned branches nationwide, we provide:
- Expert advice
- Professional-quality equipment
- Genuine replacement parts
- Ongoing support
- Fast nationwide delivery
Our Next Working Day Delivery Promise means in-stock orders placed before 11:00 am are delivered the next working day throughout New Zealand.
Contact Your Local Hygiene Direct Branch
He Waka Eke Noa – We Are All in This Canoe Together.
Frequently Asked Questions
Is DI better than RO?
Neither is universally better. DI systems are often ideal for portable, lower-volume applications, while RO systems are generally better suited to high-volume use and higher TDS water.
How do I know which system I need?
The best place to start is by testing your source water with a TDS meter and estimating how much purified water you'll produce each day.
Can I upgrade from DI to RO later?
Yes. Many professional window cleaners begin with a portable DI system and upgrade to an RO/DI system as their business expands.
How often should DI resin be replaced?
This depends on your local water quality and usage. Monitoring your TDS reading is the best way to know when replacement is required.
Do I still need DI resin if I have an RO system?
Yes. In most professional RO/DI systems, the RO membrane removes the majority of dissolved solids, while the DI resin provides the final polishing stage to achieve spot-free results.
Related Guides
Continue learning with these articles:
- Complete Guide to Waterfed Pole Systems
- How Waterfed Pole Systems Work
- Waterfed Pole vs Traditional Window Cleaning
- Pure Water Window Cleaning Explained
- How to Choose the Right Waterfed Pole Package
- DI vs RO Waterfed Systems
- Common Mistakes When Buying a Waterfed System