How Much Do Reverse Osmosis Systems Cost? (2026 Guide)
Complete 2026 pricing for countertop, under-sink, and whole-house RO systems. Includes installati...
Read ArticleDI Resin Calculator: Calculate Your System Capacity
Estimate how much deionized water your system can produce before resin replacement. Get instant results based on your water quality and system specifications.
DI Resin Calculator
* Enter your own values for an estimate
Your Estimate
Based on the values you entered
-
Total Gallons
-
Output
-
Estimated Life
Configuration:
Recommendation:
*Capacity and gallons are estimates. Actual life depends on feed water TDS, flow and usage. Cost uses the current De-Ionizer price of $395.00 per cubic foot.
How This Calculator Works
Understand the science behind our estimates
Ion Exchange Capacity
DI capacity is counted in grains of dissolved solids, and every grain removed uses part of the resin. The higher your water's TDS, the sooner the resin is spent.
The Formula
Estimated gallons = grains per cubic foot x 17.1 / (your water's TDS in PPM + an allowance for dissolved CO2 or silica) x cubic feet of resin. The 17.1 converts grains per gallon to PPM.
Cost Analysis
We calculate resin cost from the current store price of Crystal Quest De-Ionizer, divided by your estimated gallons.
Pro Tips for Maximum Efficiency
Extend Your Resin Life
Pre-treatment matters: RO removes most dissolved solids first, so the DI resin only has to polish what is left and lasts many times longer. A water softener trades calcium for sodium and leaves TDS about the same.
Monitor regularly: Check your output TDS daily. Replace resin when the reading climbs past what your use needs.
Proper flow rate: Service flow for De-Ionizer resin is 1 to 5 GPM per cubic foot working, 3 to 15 polishing.
Water Quality Variations
Seasonal changes: TDS can change with the seasons. Test monthly and adjust calculations.
Well water: If using well water, test for iron and silica, which can significantly reduce resin life.
Ready to Get Started with DI Water?
Find the perfect deionization system for your needs. Our experts can help you choose the right setup based on your water quality and application requirements.
Frequently Asked Questions
Get answers to common questions about DI resin calculations and deionized water systems
How accurate is this calculator?
It gives an estimate, not a rating or a test result. The capacity comes from our De-Ionizer data sheet, for new resin on neutral water with a little dissolved CO2 or silica. Actual results may vary based on water chemistry, temperature, and flow rates. For best results, monitor your actual TDS output and adjust accordingly.
What TDS level should I aim for in my DI water output?
It depends on your use. DI resin takes dissolved solids toward zero, and how low it gets depends on your feed water, flow and how much capacity is left, so check it with a meter against what your use needs. Replace resin when output exceeds your application's requirements.
Can I regenerate my DI resin instead of replacing it?
Mixed bed DI resin typically cannot be regenerated on-site. However, some companies offer resin exchange services where they regenerate your exhausted resin off-site, which can reduce costs. Separate bed systems can be regenerated on-site.
How do I know my resin capacity?
Check your system documentation for the resin volume in cubic feet. If it is not listed, call us at (800) 934-0051 with your tank size.
How long does DI resin last?
DI resin lifespan depends on your water's TDS level and usage volume. Higher TDS water reduces capacity, while lower TDS extends it. Enter your numbers in the calculator above for an estimate.
What is the difference between DI and RO water?
DI (deionized) water uses ion exchange resin to take dissolved solids toward zero. RO (reverse osmosis) typically removes 95 to 99% of dissolved solids. Many systems combine both.
How much does DI resin cost?
DI resin costs vary by quality and quantity. Crystal Quest De-Ionizer mixed bed resin is $395.00 per cubic foot. Calculate your cost per gallon using this calculator to determine if DI water is economical for your application.
When should I replace my DI resin?
Read your output with a TDS meter. Replace the resin when the reading climbs past what your use needs.
What size DI system do I need?
System size depends on your daily usage and water quality. Use this calculator to estimate how long a given amount of resin lasts on your water, then see our DI systems or call us at (800) 934-0051.
Can I use DI water for drinking?
DI water is not for drinking. With nearly every ion removed, it contributes almost none of the calcium and magnesium tap water can supply, and deionization does not remove bacteria or particles. It's ideal for applications requiring pure water like car washing, window cleaning, laboratories, aquariums, and manufacturing. For low-TDS drinking water, choose a Crystal Quest reverse osmosis system.
Explore Water Filtration Articles
Read expert-written educational articles on water quality, filtration technology, and treatment solutions
What Is Artesian Water? Source, Myths, and How It Compares
The word artesian describes where water comes from, not how clean it is. Here is what artesian wa...
Read Article
Types of Water Explained: Spring, Artesian, Mineral, Purified, and Distilled
A plain-language guide to every type of water, sorted by where it comes from and what has been do...
Read Article