What Is DI Resin? A Clear Guide for Window Cleaners

Deionisation (DI) resin plays a key role in pure water window cleaning. If you want spotless results on glass, frames, solar panels, cladding or conservatories, DI resin is one of the most important consumables in your system. This guide explains what DI resin is, how it works, and how to choose, store and use it correctly so you always get 000 TDS water at the brush.

Q: "What is DI Resin?"
Q: "What is DI Resin used for?"

• DI resin is a special type of mixed-bed ion exchange filter made up of tiny beads that look similar to sand. As water passes through these beads, the resin removes minerals, metals and dissolved solids. In simple terms, it turns tap water into deionised water—perfect for window cleaning because it dries completely clear without streaks or spotting.
• During the ion exchange process, unwanted ions in the water bind to the resin beads. Clean water flows out, leaving you with high-purity water that behaves like a “magnet” for dirt, dust and residue on the glass.
• Professional window cleaners rely on DI resin for water polishing, single-vessel DI systems, and as the final stage after Reverse Osmosis (RO systems) to achieve consistent 000 readings.

Q: "What does TDS mean?"

• TDS stands for Total Dissolved Solids. It measures the minerals and impurities in water. For pure water window cleaning, you want 000 TDS—anything higher can leave marks on the glass.

Q: "What does PPM mean?"

• PPM stands for Parts Per Million. It tells you how many of the particles in a sample of water are impurities rather than pure water molecules. Window cleaners aim for 000–010 PPM for reliable, spot-free results.
• You measure this using a TDS Meter, which checks purity using conductivity. You’ll quickly discover how much water quality varies between different areas!

Q: "What does 'Mixed Bed' mean?"

• Mixed-bed resin contains two types of resin beads—anions and cations—blended together to remove a wide range of impurities in one pass. This gives the purest possible output for window cleaning.

Q: "What is 'Virgin' Resin?"

• Virgin resin is brand-new resin that has never been used or regenerated. Regenerated resin can be lower quality and usually exhausts much faster. All resin we supply is premium, fresh, virgin resin for predictable lifespan and consistent purity.

Q: "What size resin vessel should I use?"

• Water purity stays the same regardless of vessel size. Whether you use 1 litre or 25 litres, the output will still be 0PPM. The difference is capacity: a larger vessel lasts much longer before the resin becomes exhausted.
• For heavy daily use, a 11L–25L DI vessel gives far better economy. If you use smaller vessels, check your TDS readings often to catch exhaustion early.

Q: "How fast does water travel through resin?"
Q: "Will my water lose pressure inside the vessel?"

• DI resin barely restricts water flow. Your pressure should remain stable. If the pressure drops suddenly, the vessel likely has trapped air—crack the lid slightly to release it.

Q: "Can I use two resin vessels in series to improve economy?"

• Yes. Using two vessels in a “daisy chain” setup can save money. The first vessel does the main filtering while the second acts as a polishing stage. When the first vessel exhausts, swap the vessels over and continue. This helps you use every bit of life from the resin.

Q: "How should I store my resin?"

• Use it within its shelf life. Resin stays good for around a year when dry and sealed.
• Keep it sealed and moist. Once opened, keep air out. Resealable tubs work best.
• Avoid freezing. Frost damages resin and shortens its lifespan.

Q: "My resin started badly and failed quickly. Is it faulty?"

• If your TDS readings were high from the start and climbed rapidly, you may have been given water softener resin by mistake. Softener resin looks similar but will not produce pure water.
• Always buy DI resin for pure water window cleaning, not softener resin.

Q: "Is there a maximum flow rate for DI resin?"

• Slow flow helps efficiency, but standard window cleaning flow rates are perfect. Your resin will purify effectively without adjustment.

Q: "Is it OK if my resin vessel freezes?"

• No. Freezing damages both the vessel and the resin. Always store vessels indoors during winter.

Q: "Should I shake my DI vessel?"

• A light shake can help reduce channelling, especially on static systems. Vehicle-mounted DI vessels move naturally when driving, so they rarely need shaking.

Q: "Should I empty the water after each use?"

• No. Keep your resin under water. Allowing it to dry reduces efficiency and shortens its life. Just protect it from frost.

Conclusion

DI resin is one of the simplest and most effective ways to create pure water for window cleaning. When you choose a high-quality mixed bed resin, monitor your TDS, and protect your resin from frost and contamination, you’ll enjoy consistent 000 readings and spotless results on every job. Whether you run a full RO/DI system or a standalone DI setup, maintaining your resin correctly keeps your running costs low and your results professional.