H2O WHR300 Whole House Filtration System Replacement Tank for NSA 300H with 3/4″ Ports (6″ x 35″)

• 6″ × 35″ structural polyglass
• Exactly the same size as NSA 300H
• Tank head has a larger O-ring for a better seal than the NSA 300H

The WHR300-NSA-300H replacement tank restores whole house system performance when an existing tank is worn, damaged, or no longer reliable. A proper replacement helps return normal flow, predictable filtration performance, and easier maintenance by bringing your system back to a known baseline.

• Use this replacement when your current tank label, paperwork, or order history shows WHR300-NSA-300H.
• Match your current valve type and connection size before purchase.
• Confirm the replacement tank footprint and height will fit your existing installation space.
• If you cannot confirm your current model number, do not guess. Identify the tank label or system documentation first to avoid ordering the wrong replacement.
• This is the right product when you want a true replacement tank solution, not a new full system redesign.

You may also consider upgrading to our large WHR935 tank.

Before You Buy the H2O WHR300: Quick Checklist

Confirm these items before ordering:

• Current tank model number confirmed on the label or paperwork
• Current valve model confirmed
• Inlet and outlet connection size confirmed
• Available height and diameter clearance measured
• Bypass type confirmed or planned
• Plumbing condition checked for worn fittings you may want to replace during the swap
• Drain line routing confirmed if your system includes backwashing
• Installation plan confirmed, DIY vs installer

The WHR935 Tank is the same height as NSA 300H, but has 3″ larger diameter. It has twice as much carbon media as NSA 300H. It also has twice the capacity and flow rate.

Order these accessories below:

Utilizing Catalytic Carbon, this unit will filter all the water throughout your entire home. This system will remove chlorine, chloramines, bad taste, and odor from all of your family’s water.

Use the WHR300 for all kitchen water needs (including drinking water, ice, juice concentrates, coffee, tea, cooking), pets and showering and bathing in clean, chlorine free water.

H2O WHR300 Whole House Filtration System Replacement Tank for NSA 300H Features:

• Structural Polyglass Tank
• Warranted for 1 year of maintenance free performance (pro-rata) with proper sediment prefiltration
• 75,000 gallon capacity for chlorine removal
• Made in the U.S.A.
• Intended for use on municipally treated water
• Do not use on microbiologically unsafe water supplies

What changes after replacement?

Replacing a tank typically restores the system to expected performance, but it is a good time to reset expectations and plan ahead.

What you can expect

• More reliable operation compared to an aging or compromised tank
• Improved consistency in flow and system performance if the old tank was restricting or leaking
• A cleaner service baseline for future maintenance and troubleshooting

What may still require attention?

• If water quality goals have changed, you may need additional treatment stages.
• If your household demand has increased, a like-for-like replacement restores the original sizing, not a higher capacity.
• If your water conditions have shifted, you may need prefiltration, softening, carbon, or UV, based on your goals.

Installation Overview for the H2O WHR300 Whole House Filtration System Replacement Tank

Always follow the instructions included with your system and local plumbing requirements.

1. Shut off the main water supply and depressurize the system.
2. Bypass the system if a bypass is installed, or isolate the line for service.
3. Disconnect plumbing connections and drain lines as needed.
4. Carefully remove the existing tank and prepare the installation area.
5. Transfer or install the correct valve and internal components according to your configuration.
6. Set the new tank in place and reconnect plumbing connections.
7. Restore water slowly and check all fittings for leaks.
8. Flush and start up the system per your instructions and confirm normal operation.
9. Verify flow and performance and recheck for leaks later the same day.

Recommended tools and supplies

• Adjustable wrenches or channel locks
• Teflon tape or approved thread sealant
• Towels and a shallow pan for drips
• Measuring tape for clearance checks
• Replacement fittings or unions if existing parts are worn

FAQs

Q: How do I confirm this replacement tank fits my system?
A: Match the model number on your current tank label or paperwork and confirm valve type and connection size.

Q: Will this change my system performance?
A: It restores the system to the expected baseline for that model. It does not increase capacity unless you choose an upgrade.

Q: Do I need to replace fittings or a bypass during installation?
A: Not always, but many homeowners replace worn fittings during a tank swap to reduce leak risk.

Q: How long does installation take on a replacement tank?
A: It depends on access and plumbing conditions. Many swaps are completed in a few hours, but complex installs can take longer.

Q: Can I install a whole house filtration system replacement tank myself?
A: Some experienced DIYers can, but a licensed installer is recommended if you are unsure about compatibility, plumbing connections, or startup steps.

Confirm your current tank model and connection size, then replace your WHR300-NSA-300H tank to restore reliable whole house performance with a clean maintenance baseline.