A nitrate water filter for the whole house runs on nitrate-selective ion exchange resin, and this collection carries the parts to build or upgrade one: Purolite Nitrate Select resin and a SoftPro control valve set up for nitrate systems. Choosing tip: get a lab test for nitrate and sulfate first, because sulfate competes for resin capacity.
-
SoftPro Water Softener, Nitrate or Tannin System Electronic Timer Control Valve
Regular price $470Regular price$700.00Sale price $470Sale -
Purolite Nitrate Select Resin - Remove Nitrates From Water - 1.0 CUFT
Regular price $450Regular price$490.00Sale price $450Sale
Nitrate Water Filter Guide: Why Your Softener, Carbon Filter and Kettle Won't Touch Nitrate
Key Takeaways
- EPA's drinking water limit (MCL) is 10 mg/L for nitrate and 1 mg/L for nitrite, both measured as nitrogen.
- CDC advises every private well owner to test for nitrates at least once a year, using a state-certified lab.
- In a USGS study of 3,465 domestic wells, nitrate exceeded the MCL in about 8% of them.
- Only three home methods remove nitrate: ion exchange, reverse osmosis and distillation. Boiling, carbon filters and standard softener resin don't.
- Sulfate competes with nitrate for exchange sites, so your sulfate result matters as much as your nitrate result when sizing a system.
- QWT sells the core parts (Purolite Nitrate Select resin, $450, and a nitrate/tannin control valve, $470), not a boxed nitrate system.
What is a nitrate water filter, and how does it work?
A whole-house nitrate water filter is an ion exchange system loaded with nitrate-selective anion resin. As water flows through the resin bed, nitrate ions are captured and chloride ions are released in their place. When the resin fills up, a salt brine regeneration restores it, much like a water softener recharges.
The key word is selective. Penn State Extension explains that ordinary anion resin prefers sulfate over nitrate, and that a saturated bed can release nitrate back into the "treated" water. Nitrate-selective resin is made to target nitrate instead.
Because the system regenerates with plain sodium chloride, it looks and runs like a softener: a control valve on top of a mineral tank, a brine tank beside it, and a drain line. The difference is inside the tank. Standard softener resin is a cation resin. It trades sodium for calcium and magnesium and can't exchange nitrate, a negatively charged ion.
Purolite Nitrate Select resin can run on its own in a dedicated nitrate system or be blended into an existing softener's resin bed, so one tank handles hardness and nitrate together.
Ion exchange vs reverse osmosis vs distillation: which removes nitrate best for you?
All three remove nitrate, but they solve different problems. Ion exchange treats every tap in the house and keeps up with normal household flow. Reverse osmosis treats drinking and cooking water at one sink. Distillation makes small batches. The right pick depends on where you need nitrate-reduced water and how much.
Penn State Extension lists ion exchange, reverse osmosis and distillation as the methods that remove nitrate from drinking water. Here's how they compare on the factors that decide a purchase:
| Factor | Ion exchange (nitrate resin) | Reverse osmosis | Distillation |
|---|---|---|---|
| Where it treats | Whole house (point of entry) | One tap, usually the kitchen sink | Countertop batches |
| How it works | Resin swaps nitrate for chloride | Pressure pushes water through a semipermeable membrane | Water is boiled, then the steam is condensed |
| What Penn State Extension reports | Sulfate reduces effectiveness. A saturated bed can release nitrate. | Membranes reject about 83–92% of incoming nitrate. Very high source water can still exceed the standard after treatment. | A typical home unit makes about 1 gallon every 4–5 hours |
| Water and energy | Uses salt and water for regeneration. The brine is high in nitrate. | Can send up to 90% of incoming water to drain, especially on low-pressure units | Uses significant electricity and gives off heat |
| Best for | ✓ Nitrate-reduced water at every tap, larger households | ✓ Drinking and cooking water only | ✓ Small volumes with no plumbing changes |
| At QWT | Resin and control valve in this collection | Reverse osmosis systems | Not carried |
Some well owners pair the two: whole-house ion exchange plus an under-sink RO system at the kitchen. If your only concern is drinking water, RO on its own is usually the simpler, cheaper project.
Why won't a water softener, carbon filter or boiling remove nitrates?
Nitrate is a small, highly soluble, negatively charged ion. Carbon doesn't adsorb it, sediment filters can't catch it, and softener resin only trades positive ions like calcium and magnesium. Boiling makes it worse: Penn State Extension notes that boiling raises nitrate concentration as water evaporates. Only a nitrate-specific method lowers it.
Here's what each common option actually does:
| Option | Removes nitrate? | Why |
|---|---|---|
| Standard water softener | ✗ No | Cation resin exchanges hardness minerals, not anions like nitrate |
| Softener with Nitrate Select resin blended in | ✓ Designed to | Adds nitrate-selective anion resin to the bed. It needs sizing to your test. |
| Carbon, pitcher or fridge filter | ✗ No | Carbon targets chlorine, taste, odor and some organics, not dissolved nitrate |
| Sediment filter | ✗ No | Catches particles. Nitrate is fully dissolved. |
| UV light | ✗ No | Disinfects bacteria. It doesn't remove dissolved ions. |
| Boiling | ✗ No, it concentrates nitrate | Water evaporates and the nitrate stays behind (Penn State Extension) |
| Reverse osmosis | ✓ Yes, at one tap | The membrane rejects most dissolved ions, including nitrate |
For bacteria or grit you'll still want UV systems or sediment filters. They just aren't nitrate tools.
What parts does a whole-house nitrate system need, and what does QWT carry?
A whole-house nitrate system needs five parts: a control valve, a mineral tank, nitrate-selective resin, a brine tank and the plumbing (bypass, drain line). QWT carries the two that make it a nitrate system, the resin and a control valve configured for nitrate service. QWT doesn't currently sell a complete, boxed nitrate system.
Keep that in mind when you compare prices: a packaged system includes the tank, brine tank and bypass, and our resin and valve prices don't. If you're rebuilding an existing unit, these may be all you need. For a new install, call us first and we'll work out the full parts list.
| Component | Its job | In this collection? |
|---|---|---|
| Control valve | Runs service, brine draw, rinse and refill on a programmed schedule | ✓ SoftPro Nitrate / Tannin System Control Valve |
| Nitrate-selective resin | Captures nitrate ions | ✓ Purolite Nitrate Select Resin, per cu ft |
| Mineral tank | Holds the resin bed, sized to resin volume | ✗ Call us to match a tank |
| Brine tank | Holds the salt for regeneration | ✗ See brine tanks |
| Bypass and drain line | Isolates the system and carries regeneration water away | ✗ Ask us what fits your valve |
The SoftPro valve's electronic timer automates regeneration, and its upgraded 1-inch ports support strong household flow. It's sold as a valve only. You connect the tank, plumbing and drain, then set the timer to your water.
How do you size and set up a nitrate system for your water?
Size a nitrate system from a full lab analysis, not from the nitrate number alone. Resin volume and regeneration frequency depend on nitrate, sulfate, hardness, your daily water use and your peak flow. Sulfate matters most. It's taken up alongside nitrate, so high-sulfate water uses up resin capacity faster.
- Read the units on your report. Nitrate can be reported "as N" (nitrate-nitrogen) or as nitrate (NO3). EPA's 10 mg/L limit is as nitrogen. Penn State Extension notes that 10 mg/L as nitrogen equals about 45 mg/L as nitrate, so mixing up the units throws the sizing off by more than four times.
- Decide: dedicated tank or blend. If you own a softener in good shape and your water is also hard, blending Nitrate Select resin into the bed lets one tank do both jobs. If nitrate is the main problem, a dedicated nitrate tank is easier to tune.
- Program regeneration conservatively. A timer valve regenerates on a schedule, not by metered use. Set it to regenerate well before the resin is exhausted.
- Plan the drain. Regeneration brine carries the nitrate the resin captured, and Penn State Extension advises care in disposing of it. Check local rules if you're on a septic system.
- Watch pH afterward. Penn State Extension notes nitrate ion exchange can make water more corrosive. If your retest shows low pH, ask us whether a pH neutralizer makes sense.
Send us your lab report and our team will recommend a resin quantity and configuration for your water, instead of guessing from a single nitrate number.
How to choose a nitrate water filter: a before-you-buy checklist
Choose a nitrate water filter by answering four questions first: how high your nitrate and sulfate are, whether you need treated water at every tap or only the kitchen, what equipment you already own, and whether you'll keep up with salt and retesting. The answers point to resin, a valve, RO or both.
- ✓ A recent lab report listing nitrate and nitrite, with units ("as N" or not).
- ✓ Sulfate, hardness, iron and pH results, all of which change how a nitrate system performs.
- ✓ A coliform bacteria result. Nitrate often comes from septic systems and manure, and those sources can carry bacteria too.
- ✓ A decision on whole house (ion exchange) vs drinking water only (reverse osmosis).
- ✓ An inventory of what you have: an existing softener, tank size, valve type, a brine tank.
- ✓ Room for a tank, brine tank, drain line and an outlet for the valve.
- ✓ A retest plan: treated water after start-up, then on a regular schedule.
When is a nitrate filter the wrong fix?
A nitrate filter is the wrong first step when you haven't confirmed the problem with a lab test, when the source can be fixed, or when only drinking water needs treatment. It's also not a substitute for your health department's guidance when someone in the home has a health concern about their water.
- The source is fixable. Penn State Extension notes shallow wells and springs are especially prone to nitrate, and a failing septic field, short well casing or runoff toward the wellhead can be the cause.
- You only need drinking water. An under-sink reverse osmosis system costs less and is easier to maintain than a whole-house tank.
- Your levels are very high or keep changing. Wells swing with rain and fertilizer season. Get repeat lab tests and talk with your county health department first.
- There's an infant in the home. EPA states that nitrate above the MCL may cause a potentially fatal blood disorder in infants under six months of age. Ask your county health department or doctor which water to use. Equipment alone isn't the answer to that question.
How should you test for nitrate before and after treatment?
Test with a state-certified laboratory before you buy anything, then retest the treated water after the system is running. CDC advises well owners to test for total coliform bacteria, nitrates, total dissolved solids and pH at least once every year, and to ask their health department what else to test for locally.
A lab report gives you the numbers a system is sized from: nitrate and nitrite (with units), sulfate, hardness, iron and pH. Test strips can flag a problem but can't size resin.
Our Ultimate Well Water Test Kit sends your sample to a certified lab, and its panels include fertilizer-related tests. Call us to confirm nitrate and nitrite are on the panel you choose before you order. Your county health department can also point you to a state-certified lab.
After installation, retest treated water once the system has run through a few regeneration cycles, then at least yearly. If treated nitrate creeps up, check salt, timer settings and resin age first.
Not sure what your nitrate water needs?
Get a free water analysis and sizing recommendation. Share your nitrate, sulfate and hardness results and we'll help you choose the resin, valve and configuration for your water. Orders ship within 1–3 business days.
Prefer to talk it through? Call 866-278-4130, Mon–Fri 9am–7pm CST.
How we built this guide: Limits and health wording come from the U.S. Environmental Protection Agency (National Primary Drinking Water Regulations). Testing guidance comes from the CDC's Guidelines for Testing Well Water. Well data comes from the U.S. Geological Survey (Focazio et al., domestic well water quality) and CDC's MMWR. Treatment details come from Penn State Extension's "Nitrates in Drinking Water." Product details come from QWT's product specifications. This is general information, not medical advice.
Nitrate Water Filter: FAQ
Does reverse osmosis remove nitrates?
Yes. Reverse osmosis is one of the three methods Penn State Extension lists for removing nitrate, and it estimates membranes reject about 83–92% of incoming nitrate. RO usually treats one tap, so it suits drinking and cooking water rather than the whole house.
Does a water softener remove nitrates?
A standard water softener doesn't. Its cation resin removes calcium and magnesium, and nitrate is an anion it doesn't exchange. Blending a nitrate-selective resin such as Purolite Nitrate Select into the softener bed, sized to your water test, adds nitrate treatment to the same tank.
Do pitcher or refrigerator filters remove nitrates?
Generally, no. Most pitcher and fridge filters use activated carbon, which targets chlorine, taste and odor, not dissolved nitrate. For drinking water, look at reverse osmosis. For every tap, look at ion exchange with nitrate-selective resin.
Does boiling water remove nitrates?
No. Boiling increases nitrate concentration because water evaporates and the nitrate stays behind, as Penn State Extension notes. Boiling is for some germs, not for nitrate.
What is the most affordable way to remove nitrates from water?
For drinking and cooking water only, an under-sink reverse osmosis system is usually the lowest-cost option. If you already own a softener in good condition, blending nitrate-selective resin into it can cost less than a separate nitrate system, if your lab results show it can keep up.
What nitrate level is too high in drinking water?
EPA's maximum contaminant level for public water is 10 mg/L of nitrate measured as nitrogen, and 1 mg/L for nitrite. Private wells aren't regulated by EPA, but Penn State Extension advises that wells meet the same limits. For questions about your household's health, contact your county health department or your doctor.
Can I mix nitrate resin with water softener resin?
Yes. Purolite Nitrate Select resin can be used on its own or mixed into a water softener's resin bed. The right ratio and total resin volume depend on your nitrate, sulfate and hardness levels and your tank size, so confirm the setup before you load it.
How often should I test my well for nitrates?
At least once a year, according to CDC, using a state-certified laboratory. If you treat for nitrate, also test the treated water after start-up and after heavy rain or flooding, since well levels can change.
Related: Reverse osmosis systems · Water test kits · Control valves · Replacement media & resin · Brine tanks · Water softeners for well water · Well water filtration systems
