Understanding Water Purification

Getting To Pure

Getting your hands on “Purified Water” is the first step. To clean windows 100% spot free, the TDS of your water needs to be at 0. There are certain cases where you can clean just slightly over 0. It all depends on what’s in the water, though. To be safe and avoid spotty windows change your resin once your TDS reading starts to creep above 0.

TDS = Total Dissolved Solids. A simple measurement of water quality.

What is My TDS?

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Can’t I just use tap water?

If you use normal tap water it will result in the glass appearing in a milky white residue. This is the result of the mineral content of the tap water. Pure water automatically absorbs the dirt. Meaning, pure water or water without any mineral content, leaves windows perfectly clean when it dries.

Across the country, water quality TDS readings fluctuate from 0 up to 1,000 or more. The lower your incoming TDS the more affordably you can produce 0 TDS spot free water.

Learn More About TDS

Total Dissolved Solids (TDS) are the total amount of mobile charged ions, including minerals, salts or metals dissolved in a given volume of water, expressed in units of mg per unit volume of water (mg/L), also referred to as parts per million (ppm). TDS is directly related to the purity of water and the quality of water purification systems and affects everything that consumes, lives in, or uses water, whether organic or inorganic, whether for better or for worse.

How Should You Purify Water?

Deionization Resin

Deionization Resin is what many window cleaners use to “Purify Water.” It can be used as a standalone filtration system or as the final step in a multistage purification system. Regardless of your water quality, Deionization Resin can be used to get you to 0 TDS.

Learn More About DI Resin

Deionization (DI) is a water filtration process whereby total dissolved solids (TDS) are removed from water through ion exchange. In simple terms, by controlling the electric charge of ions in the water, it is possible to remove the TDS. Much like a positively charged magnet will attract a negatively charged magnet (and vice-versa), DI resins attract non-water ions and replace them with water ions, leaving a more pure water form.

The big catch, however, is how long it will last. If you have a TDS on the higher end of the spectrum, you will burn through it much faster than if you start with a lower TDS.


Reverse Osmosis

Adding a Reverse Osmosis Membrane “RO Membrane” to your system will reduce your incoming TDS reading by 90%, sometimes 95%.

Learn More About RO Membranes

Reverse osmosis (RO) is a water purification technology that uses a semipermeable membrane to remove ions, molecules, and larger particles from drinking water.

Essentially your RO membrane is in place to prolong the life of your DI Resin. If your incoming TDS is above 100 it is typically more cost effective to use a multistage system with an RO membrane attached.

Multi-Stage Purification System

Common Components & Approximate Replacement Costs

Xero Pure

3 Stage System

Carbon Sediment Filter – Helps prevent material and debris from entering your RO membrane, as well as Chlorine.

Change Frequency & Replacement Cost

Change once a month during busy season, every 3 months with infrequent use. Available online or in big box stores. Cost around $7 per filter.

RO Membrane – Does all the heavy work. Removes up to 90 – 95% off all Total Dissolved Solids.

Change Frequency & Replacement Cost

With proper care, your RO membrane will last for many years. Replacement cost around $400 online.

Deionization Resin, the final step in filtration. Designed to bring your water to 0 TDS

Change Frequency & Replacement Cost

If your DI tank is part of a multistage system like shown here you will likely replace your resin a couple of times per year. Get a 1/4 cubic foot replacement for $64 online.

Proprietary VS Non-Proprietary Replacement Filters

Take note of the difference before you purchase a system.


These are great because it allows you to replace your filters at a lower cost. Typically you can also source the replacement filter from multiple vendors or even locally.

  • Carbon Sediment Filter – Available online and in big box stores
  • RO Membrane – Available from select online distributors
  • DI Resin – Available Online and locally in some areas


These type of filters typically cost more & you are limited to purchasing from one particular vendor. However, they usually do often come with an element of convenience. Think faster replacement time and ease.

4 ways to get Pure Water

Standard DI Tank

DI Tank

Best For

  • Soft Water Areas
  • Solo Operators
  • In Frequent Users

3 Stage System

Xero Pure Window Cleaning Side View

Best For

  • Hard or Soft Water Areas
  • Residential Companies
  • Frequent Users

Multi-Stage – With a Pump

IPC Eagle Hydro Cart Gas

Best For

  • Hard Water Areas
  • Commercial Companies
  • Running Multiple Poles
  • Frequent Users

Multi-Stage – With Water Tank

Tucker RO/DI Delivery System

Best For

  • Hard or Soft Water Areas
  • Bringing Your Own Water
  • Running Multiple Poles
  • Frequent Users

Keep In Mind…

ll 4 types of systems shown here will produce 0 TDS spot free water.

They all have the same essential component as the final component ”DI Resin”

The 4 Core Components of a MultiStage System

Sediment Filter

Replacement Sediment Filter

Carbon Filter

Replacement Carbon Filter

RO Membrane

RO Membrane

DI Resin

Replacement Resin

The Big Question Is..

Which type of system is best for you and which system will be the most cost efficient?

A general rule of thumb is if your TDS is under 100 a simple DI tank based system will be the most cost efficient for you. Certain areas of the country, South Carolina as an example, have very low TDS readings. We never sell multistage units into that state because they are simply not needed they are overkill.

However, if your TDS is over 100 and you intend to use the system on a regular basis, a multistage system will be the most cost effective for you. Can you use a simple DI system in a hard water area? Sure. Will you burn through your resin very quickly? Yes!


In a Multi-Stage System, the RO Membrane serves one purpose and one purpose only: to lower your TDS to a level that will extend the life of your DI Resin. They exist for this purpose only. Carbon Sediment Filters protect the RO from chlorine and sediment.

TDS VS Gallons Chart

Expected Water Production Volume

By System Type

  • Simple DI Tank – 1/2 Gallon Per Minute
  • Basic 3 Stage – 1/2 Gallon Per Minute
  • Multi-Stage With Water Tank – 1 Gallon Per Minute
  • Multi-Stage On Demand With Pump – 1.5 Gallons Per Minute

How Much Do I Need?

  • 1 operator can clean with 1/4 – 1/2 a gallon per minute.
  • 2 operators cleaning @ the same time – 1 gallon per minute.
  • 3 operators cleaning @ the same time – 1.5 gallons per minute.

Keep Reading

Understanding Water Fed Poles and Purification.